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Action of clonidine on micturitional reflexes in decerebrate cats
Brain Research, 491 (1989) 45-56 Elsevier
45
BRE 14596
Action of clonidine on micturitional reflexes in decerebrate cats C6sar Galeano 1, Jacques
Corcos 2, Michel Carmel 2 and Bruno Jubelin 1'*
Departments of t Physiology and Biophysics and 2Urology, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Que. (Canada) (Accepted 6 December 1988)
Key words: Decerebrate cat; Clonidine; Yohimbine; Bladder; Urethra
We explored the urodynamic action of clonidine (preferential a2-agonist) and yohimbine (preferential a2-blocker) in decerebrate cats. These animals retain catecholaminergic fibers from the complex of the locus coeruleus to the spinal cord and have synergic and faster micturition cycles than normal cats. Twenty-nine male cats were made decerebrate at intercollicular level under ether anesthesia. Voiding, vesical, urethral and blood pressures, and the EMG of the external sphincter-pelvic floor and leg muscles were studied. Preparations with the urethrovesical junction opened and closed were used. Control activity was characterized by two types of vesical pressure waves: (1) low frequency, high intensity, and (2) high frequency, low intensity. Type-2 preceded Type-1 waves. Clonidine caused: (A) reduction of Type-1 and enhancement of Type-2 Pveswaves; (B) diminution of vesical capacity; (C) facilitation of external sphincter relaxation; (D) inhibition of skeletal muscle activity; (E) systemic hypotension and bradycardia. Yohimbine inhibited clonidine's actions. When injected alone, it inhibited vesical and increased sphincteric activities. It also produced systemic hypertension and enhanced crisis of autonomic dysreflexia. The overall effect of clonidine on urodynamics in acute decerebrate cats was to bring about an active, small (normotonic) bladder with urinary frequencies. We suggest that clonidine: (1) inhibited Type-1 waves by inhibiting cellular activity in the locus coeruleus. As a result, the vesico-vesical contraction long loop reflex was abolished; (2) facilitated Type-2 waves by inhibiting inhibitory interneurons in the sacral parasympathetic center. As a result, the vesicovesical contraction short loop reflex was facilitated.
INTRODUCTION Urodynamic action of central catecholaminergic elements has been studied in humans 41-43'45,46, cats ~8"19 and rats 36,55. We have shown 19 that clonidine (a2-adrenergic agonist) can partially correct the underactive detrusor and detrusor-sphincter dyssynergia syndromes in chronic spinal cats, suggesting that the absence of descending noradrenergic (NA) fibers and the persistence of spinal a2-receptors in target neurons may play a role in vesicourethral physiopathology. Electrophysiological studies have demonstrated the inhibitory action of clonidine on the sympathetic CNS outflow to the lower urinary tract 11'31 and on pudendal nerve reflexes 14. On the whole, it has been demonstrated that bladder and external sphincter activities may be profoundly
modified by manipulating central catecholaminergic mechanisms, but our understanding of central adrenergic action on micturition remains incomplete. The catecholaminergic (CA) neurons that control the CNS are located in the brainstem, and the main centers are the locus coeruleus and subcoeruleus nuclei. They form the 'complex of the locus coeruleus' (CLC) in the dorsolateral pontine tegmentum. The C L C can influence micturition through ascending and descending efferent pathways. Ascending pathways are widespread in the brain and cerebellum, and might indirectly influence micturition through the control of motor, emotional and motivational states. Descending fibers originate in the ventral part of the C L C and innervate practically all spinal gray matter t7,37. They form two bilateral and partially crossed main pathways: the coeruleus-
* Present address: Department of Neurosciences, McMaster University, Hamilton, Ont., Canada L8N 3Z5. Correspondence: C. Galeano, DEpartement de Physiologie et Biophysique, Facult6 de M6decine, Universit6 de Sherbrooke, Sherbrooke, Que., Canada J1H 5N4, 0006-8993/89/$03.50 (~) 1989 Elsevier Science Publishers B.V. (Biomedical Division)
46 spinal, ending in the sacral parasympathetic nucleus of the pelvic nerve, and the lateral tegmental-spinal, ending in the thoracolumbar sympathetic nucleus of the hypogastric nerve 3-~'s3"54. Electrical stimulation of the LC induces vesical contractions current- and frequency-dependent, via the coeruleus-spinal pathway s-s, and the lesion of the LC produced immediate urinary retention 44. Is the CLC the 'Barrington's brainstem micturition center'? Strong evidence suggests that it plays an important role in micturition, but it is not the only brainstem nucleus to participate in the control of bladder activity. More experiments are needed to elucidate the exact role of the LC in micturition. The aim of this study was to observe cionidine's action on vesical and urethral activities in acute decerebrate cats and to infer its effects on micturition reflexes at brainstem (long loops reflexes) and sacral levels (short loops reflexes). MATERIALS AND METHODS Male cats weighing 2.5-4.5 kg were submitted to ether anesthesia, parieto-occipital craniotomy, occipital lobectomy and brainstem transection at intercollicular level. Anesthesia was discontinued and the skin was sutured with wound clips. Body temperature was controlled with a rectal thermistor (Ellab) and a heater. Blood pressure was controlled at the level of the carotid artery through an heparinized (Hepalean, OR) catheter and transducer (Bentley). A catheter was set into the femoral vein or the abdominal cavity for intravenous (i.v.) or intraperitoneal (i.p.) drug injections, respectively. For intrathecai (i.t.) administration of drugs we anesthetized the lumbar skin and dorsal muscles with lidocaine 1% (Squibb) to avoid nociceptive reflexes. A partial laminectomy was done at L 6 level and a fine catheter (o.d. = 0.3 mm) was introduced caudally in the subarachnoid space to the end of the dural sac, through a small hole in the dura mater. We used cyanoacrylate (Kraze Glue II) to fix the catheter and to seal the dura mater, avoiding rapid systemic absorption of drugs. Muscles and skin were sutured with silk thread. Two procedures to study vesicourethrai activity were used. (A) Bladder and urethra connected: the bladder was exteriorized through a suprapubic inci-
sion. A fenestrated F5 catheter was fixed through the bladder and connected to a pump (Harvard) and transducer (Bentley) for vesical pressure (Pv~,~) recording. Bladder infusion rate was 1.91 ml/min with lukewarm saline solution. This preparation allows study of urodynamics with the advantage of normal vesical emptying and urethral excitation by the periodic flow of urine during voiding. Twenty animals with micturition Pattern II, characterized by a continuous jet of urine followed by intermittent jets 2s'2~, were selected. In 4 cats a urethral catheter was added to measure urethral pressure (Pur~,)" (B) Bladder and urethra disconnected: in 9 animals, bladder neck and proximal urethra were carefully dissected keeping regional vasculature and innervation as intact as possible. Two flexible catheters (Minicath infusion set) were inserted through a hole in the proximal urethra and ligated, one towards the bladder, the other towards the urethra. The open ends were less than 1 cm from ligature. The remaining tissue between both ligatures was sectioned, so that the bladder and urethra were totally independent. Each catheter was connected through a T adaptor with separate pumps (Harvard) and transducers (Bentley). Bladder infusion rate was 1.91 ml/min until a regular rhythm of vesical waves was present. Infusion was then stopped or was reduced to 0.382 ml/min. Voiding was impossible. The vesicovesical contraction reflex was activated without the interplay of urethrovesical reflexes generated by the periodic transit of urine in the urethra. The urethra was perfused at a rate of 0.191 or 0.382 ml/min, constant in each cat, and the resistance to flow was approximately estimated by the Pur," This constant, slow perfusion rate did not elicit urethral reflexes. These techniques are modified versions of previously published m e t h o d s 2°'23'27"29. The E M G of the external sphincter-pelvic floor striated muscles (EMGes) was studied with coaxial (Kopf) or parallel (Grass) needle electrodes in a juxta-urethrai, subpubic site that showed intense activity when bulbocavernosus reflexes were activated. The E M G of hind leg muscles (EMGhl) was obtained with parallel Grass needle electrodes. All the inputs were connected to a Grass D polygraph. Urine flow (UF) was visually controlled and registered on records with an ON-OFF switch. We studied the cystosphincterograrn, including P,,~,
47 P ..... UF and EMGs. The urodynamic study is started at least 1 h following interruption of anesthesia. The following drugs were administrated: (a) clonidine hydrochloride (CLON) (Boeringer Ingeheim or Sigma) as a preferential a2-agonist that crosses the blood-brain harrier (BBB), in doses of 0.020.12 mg/kg i.v. or i.p., and 3-5 /~g/kg, i.t.; (b) yohimbine hydrochloride (YOH) (Welker Lyster or Sigma) as a preferential a2-antagonist that crosses the BBB, in doses of 0.2-1 mg/kg, i.v. or i.p., and 30 ltg/kg, i.t.; (c) trimethaphan camsylate (Arfonad, Roche) in doses of 0.5-0.7 mg/kg, i.v. We used the i.v. route to get fast and high blood concentration of drugs, the i.p. to get a slower, more progressive increase of blood drug concentration, reducing unspecific receptor stimulation or inhibition of other than a2-receptors, and the i.t. to get direct, isolated CNS action. Descriptive statistics (mean and S.D.) and t-tests for independent and dependent samples were done using the MacSS StatSoft program. RESULTS
Behavior Intercollicular decerebration produced the classic 'rigidity' characterized by stiffness of extensor muscles of the 4 limbs and clenching of the jaw. There was intense exaggeration of stretch reflexes. Animals were in coma. Breathing and circulation were approximately normal. CLON reduced rigidity. YOH increased rigidity and induced or exaggerated locomotion-like movements. When injected rapidly, cats died after a rigidity crisis.
Neurourodynamics Control Preparation A. In all animals, (n = 20) bladder contractions were associated with relaxation of sphincters (evaluated by reduction of the EMGes activity) and voiding with repeated pelvic floor contractions (Pattern II micturition) 25'28 (Figs. 1-3). Vesicovesical contraction (short and long loops), vesicourethral relaxation, urethro-urethral contraction, and urethrovesical contraction reflexes were acting (for a brief description of these reflexes see2°).
Preparation B. In all animals (n = 9) Pattern I micturition 25'zs was observed, characterized by isolated vesical contractions without pelvic floor contractions (Fig. 4). Resistance to urethral flow (P,ra) was variable, showing small increases or decreases. EMG activity decreased during Pves waves in all animals. Because there was no voiding, the urethrourethral contraction and urethrovesical contraction reflexes were not activated. Two types of Pvc~ waves were observed (Table I, control): low-frequency, high-intensity and longduration, triggered at a bladder volume of 25 ml or more (Type 1), and fast-frequency, low-intensity and short-duration, triggered at a bladder volume of 5 ml or more (Type 2). In preparation A, Type-1 waves had a first regular period, followed by a series of superimposed irregularities associated with bulbocavernosus contractions, characteristic of Pattern-II micturition. These complex high-intensity waves were preceded by low intensity Type-2 waves (Fig. 1). In preparation A, Type-1 and Type-2 waves were significantly different (P < 0.001) (Table I). In preparation B, only regular Type-1 waves (Table II, control) were observed (Fig. 4). Type-1 waves in preparation B, were more frequent, intense and of shorter duration than Type-1 waves in preparation A without urethral catheter (P < 0.001). They had a small difference in intensity (P < 0.05) with Type-1 waves in preparation A. Frequency and duration were significantly different (P < 0.001) when a urethral catheter was used (see control, Tables I and n). Clonidine Preparation A. Following CLON administration at doses higher than 0.02 mg/kg, i.v. or i.p., total but transitory inhibition of Type-1 Pve~ waves, significant facilitation or increase of Type-2 Pve~ waves (Table I, clonidine), and inhibition of striated muscle activity were observed. In preparation A with a urethral catheter - - which augments urethral resistance - the increase in intesity (P < 0.001) and duration (P < 0.001) of Type-2 waves was more significant than in preparations without urethral catheter. This effect was present for 1-2 h (n = 6) using smaller doses (0.02-0.03 mg/kg) and was still present 7 h (n = 3) following administration of the highest doses of CLON (0.10-0.12 mg/kg). Doses of 0.05-0.10 mg/
48
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Fig. I. Action of clonidine. Preparation A (bladder and urethra connected). In all figures, injection of drugs is marked by a textured bar; injection starts at the beginning and finishes at the end of the bar. Control: note Pattern-II micturition: a first period with a continuous urine jet and sphincter relaxation, followed by a second period of irregular, high Pve~wave, bulbocavernosus contractions and intermittent jets of urine. This is not a detrusor-sphincter dyssynergia, but a normal, essential period for total bladder emptying. At the end of the Pw~ wave the external sphincter (EMGes) contracts. Clonidine: time scale (abscissa) changed. Note the high-frequency, low-intensity Pves waves (Type 2), starting the voiding cycle. They slightly increase in intensity and are followed by high-intensity, low-frequency Pw~ waves (Type 1), indicated by an asterisk. Note the increase in intensity of Type-2 and reduction of Type-/waves. Facilitation of Type-2 waves produces a paired pattern; after 30 min, typical single activity associated with voiding is seen. After 60 min, the action of this weak dose of clonidine is still present. Note the progressive reduction of EMG activities and long-lasting hypotension.
kg, i.v., were used to test the blocking effect of Y O H (n = 8). l.t. administration ( 3 - 5 /~g/kg) (n = 3) p r o d u c e d u r o d y n a m i c actions similar to those of the i.v. route. Control i.t. injections of vehicle alone p r o d u c e d a small and irregular response for 1-2 min when injected rapidly; with slow administration, no response was observed. I.t. injected volume was 0 . 1 - 0 . 2 ml. Note in Figs. 1 and 2 the progressive inhibition of Type-1 waves, waning of Pattern-II micturition, reduction o f vesical capacity, increased
intensity of Type-2 waves, urinary frequency and intense reduction o f E M G activity. N o urine retention was observed. I.p. injection elicited effects similar to that of i.v., but they were slower to appear. U r o d y n a m i c effects were always associated with systemic hypotension and bradycardia. I.t. administration of C L O N p r o d u c e d small cardiovascular and striated muscle actions and intense urodynamic responses (Fig. 5). Preparation B. Large Type-1 Pves waves were
49 TABLE I Vesical waves
Preparation A. Values are mean + S.D. With urethral catheter (n = 4)
Without urethral catheter (n = 10) Freq. (rain)
Int. (ram Hg)
Dur. (s)
Freq. (min)
Int. (mrn Hg)
Dur. (s)
Control Type-1 waves Type-2 waves
0.241 + 0.223 2.300 + 0.888
38.740+ 8.409 7.000 + 1.414
57.100+ 9.960 10.100+ 2.767
0.397 + 0.080 2.250 + 0.500
64.000+ 7.528 4.250 + 1.258
66.000+ 7.528 10.750+ 2.217
Clonidine Type-1 waves Type 2-waves
0.000 + 0.000 1.900 + 0.358*
0.000 + 0.000 0.000+ 0.000 11.500 + 2.168" 20.000+ 1.673"
0.000 + 0.000 2.125 + 0.299
0.000 + 0.000 35.250+ 6.752
0.000 + 0.000 21.00+ 1.414
*n=6.
totally inhibited for a short time, allowing Type-2 waves to a p p e a r (Table II, clonidine). Finally, Type-1 waves were re-established (Fig. 4). Yohimbine Preparation A . Low doses (0.2-0.4 mg/kg, i.v.) of
Y O H antagonized C L O N effects, restoring micturition p a t t e r n II and striated muscle activity (n = 5) (Fig. 2). A t high doses (0.5-1 mg/kg, i.v.) it inhibited vesical activity (n = 3) (Fig. 3). In Fig. 3, we a d m i n i s t e r e d tubocurarine before Y O H to eliminate Y O H striated muscle action enhancement. Note the change from Pattern-II to Pattern-I micturition when bulbocavernosus contractions were blocked by tubocurarine; b l a d d e r activity was inhibited. A t doses of 1 mg/kg i.v., Y O H facilitated crises of rigidity when no neuromuscular blocking drug was used. By i.t. route Y O H (30 ktg/kg) inhibited C L O N action and b l a d d e r activity (n = 3) (Fig. 5). Preparation B. A t low doses (0.2-0.5 mg/kg, i.v.) Y O H briefly inhibited b l a d d e r activity for a short
time and enhanced bulbocavernosus and urethrovesical contraction reflexes (n = 4). A t high doses (0.5-1 mg/kg, i.v.) longer b l a d d e r inhibition was observed, followed by a long-lasting period of bulbocavernosus reflex enhancement (n = 2) (Fig. 4). Ganglionic blockade Trimethaphan (0.5-0.7 mg/kg, i.v.) p r o d u c e d ganglionic b l o c k a d e and inhibited Type-1 and Type-2
activity. Fig. 6 shows inhibition of Type-2 waves after administration of C L O N (n = 3). DISCUSSION This study on acute, d e c e r e b r a t e cats showed the presence of two types of vesical waves and a differential action of C L O N on these vesical activities; inhibition, facilitation. A r e Pves waves neurogenic or myogenic? O u r experiments using the ganglionic blocking agent t r i m e t h a p h a n confirmed previous reports 34'35 showing that both types of
TABLE II Vesical waves
Preparation B. Values are mean + S.D. Control (n = 9)
Clonidine (n = 5)
Freq. (rain)
Int. (ram Hg)
Dur. (s)
Freq. (min)
Type 1
0.926 + 0.108
75.111+ 8.238
35.444+ 3.644
0.000 + 0.000
0.000 + 0.000
0.000 + 0.000
Type 2
0.000 + 0.000
0.000 + 0.000
0.000+ 0.000
2.960 + 0.336
15.200+ 0.837
16.400+ 1.949
Int. (ram Hg)
Dur. (s)
51 CONTROL EmGes
~::;
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-
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~, - ~ "
•
, _~j,
i
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PVES
,oo[ 0/
OI
T U B O C U R A R I n E 1 mg/kg/tv It
YOHImBInE
,
h
1rng/kg/lv
m 1
rain
Fig. 3. Action of clonidine, tubocurarine and yohimbine. Preparation A. Note the typical Pattern-II voiding. After tubocurarine, the striated muscle activity disappears and Pattern-I micturition is observed. Yohimbine inhibits vesical activity.
vesical waves were of neurogenic origin. Is bladder activity organized at central or peripheral level? The use of the i.t. route showed centrally mediated CLON urodynamic actions, as previously reported 26" 36. In addition, it has been demonstrated that CLON affected the urethral reflex response elicited by stimulation of the pudendal nerve, but had no effect on the direct responses elicited by stimulation of the peripheral end of the same cut pudendal nerve 14. Urodynamic central actions of CLON are well demonstrated, but the exact mechanism in brainstem, posterior, intermediate or anterior horns, motoneurons or interneurons, remains to be elucidated. Peripheral vesical and urethral actions of
CLON were described in in vitro experiments 1,36. In whole animal experiments, peripheral CLON action might affect vesical performance (for example, a small change in Pves intensity), but it seems to have no importance in the central regulation of micturition reflexes. How can we interpret CLON's actions in the context of vesical reflexes? Vesical distension produces reflex vesical contraction. This is accomplished by activation of two reflex arcs: the long loop of the brainstem vesicovesical contraction reflex 2,3 and the short loop of the spinal vesicovesical contraction reflex 7,12. Progressive vesical distension elicited two types of Pves waves: slow-frequency,
52 ioomr*mg
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f',
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o 8 mg/Kg/iv
Fig. 4. Action of clonidine and yohimbine. Preparation B (bladder and urethra separated). Note the Pattern-I micturition before the injection of clonidine (textured horizontal bar), Clonidine inhibits the large Pvcs waves (Type 1). Smaller, faster waves (Type 2) appear briefly for about 23 min, and then, Type-1 waves reappear (records are continuous). A first injection of 0.5 mg/kg, i.v., of yohimbine (injection was done 5 min before the record) radically changes bladder and urethral activities. The sharp Pu,, waves correspond to bulbocavernosus reflexes. They are followed by bladder contractions (urethrovesical contraction reflex). A second injection of yohimbine (0.8 mg/kg, i.v.) (illustrated) inhibits the large P,~ waves and again the small, fast Type-1 P,es waves appear for about 27 min, before the activity becomes similar to that of the first injection record. This activity persists for more than 1 h. Bladder volume increases from 30 to 70 ml.
high-intensity, long-duration waves, triggered at large b l a d d e r volume (Type 1), and fast frequency, small intensity, short duration waves, triggered at low b l a d d e r volume (Type 2), as previously r e p o r t e d
in anesthetized rats 34'35. We suggest that progressive b l a d d e r distension triggers first the spinal vesicovesical contraction reflex, which produces small Type-2 waves; then, this activity triggers the brain-
53
stem vesicovesical contraction reflex, responsible for intense Type-1 waves. The long loop function would be fundamentally the multiplication or amplification of the spinal reflex6"3z. The integrative center of the long loop reflex is in the brainstem, probably including the complex of the LC. For this reason, bladder motility is modified by drugs that change CLC activity. CLON inhibits LC activity~-"~JT" 22.24.49; as a result, it blocks the brainstem vesicovesical contraction reflex and reduces Type-1 Pves waves. On the other hand, it increases the activity of the spinal vesicovesical contraction reflex m. How can CLON increase the spinal vesicovesical contraction reflex? In general, CLON action on spinal neurons is inhibitory37 and noradrenaline inhibits firing of preganglionic neurons 26. The facilitation of the spinal vesicovesical contraction reflex probably involves inhibition of a negative feedback controlling the gain of the reflex (an inhibition of inhibitory
interneurons), and/or suppression of the sympathetic outflow to the periphery. The final balance between both actions in preparation A, with opened urethrovesical junction, was a very active bladder with small vesical capacity, intense, frequent contractions of spinal origin and urinary frequency. When the urethrovesical junction was ligated and no voiding was possible (preparation B), bladder distension was progressive and continuous producing intense activation of brainstem centers. Under these circumstances, the inhibition of the LC elicited by CLON, blocked the large waves and allowed the spinal waves to appear for a short time. Then, the continuous, progressive bladder distension overcame CLON inhibition and brainstem Type-1 activity reappeared. YOH inhibited CLON urodynamic effects and when injected alone or in high doses, it antagonized sacral parasympathetic activation, eliminating or sharply reducing bladder activity as pre-
CODTROL
501rnmHg uF
, .1 ! Fl!
CLODIDIDE
YOHImBIDE
DteSg •
5 .glkg/IT
30 lag/kg/IT
~
0 ITIIn. I
Fig. 5. Action of i.t. clonidine and yohimbine. Preparation A. Control: note the typical Pattern-II micturition with Type-1 Pves waves preceded by Type-2 waves. Administration, i.t., of clonidine inhibited Type-1 Pve~ waves, enhanced Type-2 waves and produced dribbling. I.t. yohimbine briefly inhibited bladder activity.
54
CLOFIIDIFIE
3 lag/kg/IT
TRIlTIETAPHAFI
o.s m o / k g / l v
2 0 0 ~nrnHg
BP
Pves
o 5O "nmHg
o D~c sE~ 4
13q I F1
~
Fig. 6. Action of trimethaphan, preparation A. I.t. administration of clonidine induced rhythmic Type-2 Pve~ waves. I.v. trimethaphan blocked these vesical waves and reduced blood pressure. viously demonstrated in spinal cats 19. The mechanisms is probably indirect, by disinhibiting negative feedback and increasing sympathetic outflow from the CNS, because vesical contractions elicited by electrical stimulation of the locus coeruleus are not inhibited by i.t. Y O H 55. Passage of urine through the urethra during voiding stimulates urethral mechanoreceptors and triggers the urethrovesical contraction reflex. This is synergistic with the vesicovesical contractor reflex and allows the detrusor to continue contraction when bladder volume diminishes. The urethrovesical contraction reflex has brainstem and spinal loops 3-5. In preparation A, the reflex was normal; in preparation B, the reflex was absent and voiding was impossible. It is difficult to specify CLON action on this reflex in preparation A. Inhibition of the brainstem loop is probably compensated by enhancement of the short loop. Passage of urine through the urethra during voiding still elicited other reflexes, such as urethrourethral contraction and bulbocavernosus reflexes 2°' 21. These reflexes produce a sharp Pura increase and trigger the urethrovesical contraction reflex. All these contraction reflexes (vesicovesical, urethrovesical, urethro-urethral and bulbocavernosus) sustain Pattern II micturition in cats. The urethrourethral contraction reflex was normal in preparation A and absent in preparation B. When present, it was intensely inhibited by CLON. This drug inhibits striated muscle hyperactivity in decerebrate or spinal animals and spastic patients 19'3°'3s-4°'5°'51. Bulbocavernosus and urethro-urethral contraction reflexes were inhibited and Phase II micturition pattern vanished. CLON also inhibits pudendopudendal reflexes ~4, which are related to urethro-
urethral contraction and bulbocavernosus reflexes. Humans do not have Pattem-II micturition and the urethro-urethral reflex is observed during the filling phase as an emergency reflex that guards continence 21. The increase of bladder volume and/or pressure elicits another fundamental voiding reflex: the vesico-urethral relaxation reflex that opens sphincters 3-5"15"16"21"32.Relaxation of skeletal muscles reduces urethral resistance to flow and facilitates voiding. This reflex was not substantially modified by CLON. During the first period of continence, the filling of the bladder is maintained by passive factors, depending on the bladder neck structure. Later the vesicourethral contraction reflex is activated assuring urethral closure 13"21'29"32'48'52. CLON inhibits the striated component of this reflex. Moreover, the sympathetic inhibition decreases sphincteric smooth muscle tonus, so that even small Pves waves elicit voiding. CONCLUSIONS
In unanesthetized acute decerebrate cats, i.v., i.p. and i.t. administration of clonidine produces the following urodynamic effects: (1) it inhibits the low-frequency, large Pves waves (Type 1), probably by inhibiting the brainstem long loop of the vesicovesical contraction reflex; (2) it inhibits Pattern-II feline micturition, probably by inhibiting the urethro-urethral contraction and bulbocavernosus reflexes; (3) it facilitates the fast frequency, small Pves waves (Type 2), probably by inhibiting negative feedback loops linked to the spinal short loop vesicovesical contraction reflex and/or the sympa-
55 thetic outflow from the CNS; (4) it reduces vesical capacity and produces urinary frequency; (5) it enhances relaxation of urethral sphincters. The final effect is a small, very active bladder with urinary frequency. Besides these urodynamic effects, CLON produces striated muscle relaxation, hypotension and bradycardia. YOH antagonizes all CLON's effects. When injected alone, it produces bladder inhibition, hypertension, tachycardia and rigidity crisis. REFERENCES 1 Andersson, K.E., Mattiasson, A. and Sjogren, C., Electrically induced relaxation of the noradrenaline contracted isolated urethra from rabbit and man, J. Urol., 129 (1983) 210-214. 2 Barrington, J.F.J., The nervous mechanism of micturition, Q. J. Exp. Physiol., 8 (1914) 33-71. 3 Barrington, J.EJ., The relation of the hind-brain to micturition, Brain, 44 (1921) 23-53. 4 Barrington, J.F.J., The component reflexes of micturition in the cat. Parts I and II, Brain, 54 (1931) 117-188. 5 Barrington, J.F.J., The component reflexes of micturition in the cat. Part III, Brain, 64 (1941) 239-243. 6 Bradley, W.E., Micturition reflex amplification, J. Urol., 101 (1969) 403-407. 7 Bradley, W.E. and Teague, C.T., Spinal cord organization of micturition reflex afferents, Exp. Neurol., 22 (1968) 504-516. 8 Byrum, C.E., Stornetta, R. and Guyenet, P.G., Electrophysiological properties of spinally-projecting A5 noradrenergic neurons, Brain Research, 303 (1984) 15-29. 9 Cedarbaum, J.M. and Aghajanian, G.K., Noradrenergic neurons of the locus coeruleus: inhibition by epinephrine and activation by the alpha-antagonist piperoxan, Brain Research, 112 (1976) 423-429. 10 Cedarbaum, J.M. and Aghajanian, G.K., Catecholamine receptors on locus coeruleus neurons: pharmacological characterization, Eur. J. Pharmacol., 44 (1977) 375-385. 11 De Groat, W.C. and Douglas, J.W., The effects of L-5-hydroxytryptophan (5-HTP) and clonidine on central sympathetic and parasympathetic reflex pathways to urinary bladder of the cat, Fed. Proc., 34 (1975) 795. 12 Denny Brown, D. and Robertson, E.G., On the physiology of micturition, Brain, 56 (1933) 149-190. 13 Downie, J.W. and Awad, S.A., The state of urethral musculature during the detrusor areflexia after spinal cord transection, Invest. Urol., 17 (1979) 55-59. 14 Downie, J.W. and Bialik, G.J., Clonidine suppresses somatic and viscerosomatic reflex activity evoked on the pudendal nerve in cats, Neurourol. Urodyn., 3 (1987) 141-143. 15 Edvarsen, P., Nervous control of urinary bladder in cats, I. The collecting phase, Acta Physiol. Scand., 72 (1968a) 157-171. 16 Edvarsen, P., Nervous control of urinary bladder in cats. II. The expulsion phase, Acta Physiol. Scand., 72 (1968) 172-182. 17 Fung, S.J. and Barnes, C.D., Locus coeruleus control of
ACKNOWLEDGEMENTS
The authors are grateful to Mr. Pierre Gagn6 and Miss Ann Graillon for their efficient help in several experiments. We also wish to express our thanks to Boering Ingeheim Canada Ltd. and Welker Lyster Lt6e. for their respective donations of clonidine and yohimbine.
spinal cord activity. In C.D. Barnes (Ed.), Brainstem Control of Spinal Cord Function, Academic Press, New York, 1984, pp. 215-255. 18 Gajewski, J., Downie, J.W. and Awad, S.A., Experimental evidence of a central nervous system site of action in the effect of alpha-adrenergic blockers on the external sphincter, J. Urol., 133 (1984) 403-409. 19 Galeano, C., Jubelin, B., Carmel, M. and Ghazal, G., Urodynamic action of clonidine in the chronic spinal cat, Neurourol. Urodyn., 5 (1986) 475-492. 20 Galeano, C., Jubelin, B., Germain, L. and Guenette, L., Micturitional reflexes in chronic spinalized cats. The underactive detrusor and the detrusor-sphincter dyssynergia, Neurourol. Urodyn., 5 (1986) 45-63. 21 Garry, R.C., Roberts, T.D.M. and Todd, J,K., Reflexes involving the external urethral sphincter in the cat, J. Physiol. (Lond.), 149 (1959) 653-655. 22 Geyer, M.A. and Lee, E.H.Y., Effects of clonidine, piperoxane and locus coeruleus lesion on the serotoninergic and dopaminergic systems in raph6 and caudate nucleus, Biochem. Pharmacol., 33 (1984) 3399-3405. 23 Girado, J.M. and Campbell, J.B., The innervation of the urethra of the female cat, Exp. Neurol., 1 (1959) 44-64. 24 Guyenet, P.G., The coeruleus-spinal noradrenergic neurons: anatomical and electrophysiological studies in the rat, Brain Research, 189 (1980) 121-133. 25 Hassouna, M., Abdel-Rahman, M., Galeano, C., Lamarche, J. and Elhilali, M.M., La physiologie v6sico-ur6trale pendant la continence et la miction chez le chat, J. Urol., 89 (1983) 201-206. 26 Hisamitsu, T. and De Groat, W.C., The depressant effects of clonidine applied intracerebroventricularly and intrathecally on the sympathetic outflow to the urinary bladder of the cat, Pharmacologist, 25 (1983) 161. 27 Jonas, U. and Tanagho, E.A., Studies on vesicourethral reflexes. I. Urethral sphincteric responses to detrusor stretch, Invest. Urol., 12 (1975) 357-373. 28 Jubelin, B., Galeano, C., Ladouceur, D., Lemaire, S. and Elhilali, M.M., Effect of enkephalin on the micturition cycle of the cat, Life Sci., 34 (1984) 2015-2027. 29 Kiruluta, H.G., Downie, J.W. and Awad, S.A., The continence mechanisms: the effect of bladder filling on the urethra, Invest. Urol., 18 (1981) 460-465. 30 Knutsson, E., Martensson, A. and Gransberg, L., Antiparetic and antispastic effects induced by tizanidine in patients with spastic paresis, J. Neurol. Sci., 53 (1982) 187-204. 31 Krier, J., Thor, K.B. and De Groat, W.C., Effects of clonidine in the lumbar sympathetic pathways to the large
56
32 33
34
35
36
37
38 39
40 41
42
43
44
45
intestine and urinary bladder of the cat, Eur. J. Pharrnacol., 59 (1979) 47-53. Kuru, M., Nervous control of micturition, Physiol. Rev., 45 (1965) 425-494. Loewy, A.D., Saper, C.B. and Baker, R.P., Descending projections from the pontine micturition center, Brain Research, 172 (1979) 533-538. Maggi, C.A., Santicioli, P. and Meli, A., Sympathetic inhibition of reflex activation of bladder motility during filling at a physiological-like rate in urethane anaesthetized rats, Neurourol. Urodyn., 4 (1985) 37-45. Maggi, C.A., Santicioli, E and Meli, A., The effect of hexamethonium on the distension-induced contractile activity of the rat bladder: evidence for the existence of a spinal 'short-loop' vesico-vesical reflex in rats, Neurourol. Urodyn., 5 (1986) 403-410. Maggi, C.A., Santicioli, P., Furio, M. and Meli, A., Dual effects of clonidine on micturition reflex in urethane anesthetized rats, J. Pharmacol. Exp. Ther.. 235 (1985) 528-536. Marshall, K.C., Catecholamines and their actions in the spinal cord. In R.A. Davidof (Ed.), Handbook of the Spinal Cord, Vol. 1, Dekker, New York, 1983, pp. 275-327. Maynard, EM., Early clinical experience with clonidine in spinal spasticity, Paraplegia, 24 (1986) 175-182. Naftchi, N.E., Functional restoration of the traumatically injured spinal cord in rats by clonidine, Science, 217 (1982) 1042-1044. Nance, P.W., Shears, A.H. and Nance, D.M., Clonidine in spinal cord injury, Can. Med. Assoc. J., 133 (1985) 41-42. Nordling, J., Meyhoff, H.H. and Christensen, N.J., Effects of clonidine (Catapresan) on urethral pressure, Invest. Urol., 16 (1979) 289-291. Nordling, J., Meyhoff, H.H. and Christensen, N.J., Influence of sympathetic tonus and plasma noradrenaline on urethral pressure, Scand. J. Urol. Nephrol., 15 (1981) 1-6. Nordling, J., Meyhoff, H.H. and Hald, T., Sympatholytic effect on striated urethral sphincter, Scand. J. Urol. Nephrol., 15 (1981) 173-180. Osumi, Y., Oishi, R., Fujiwara, H. and Takaori, S., Hyperdipsia induced by bilateral destruction of the locus coeruleus in rats, Brain Research, 86 (1975) 419-427. Pedersen, E., Torring, J. and Klemar, B., Effect of the alpha-adrenergic blocking agent thymoxamine on the
46
47
48
49
50
51
52
53
54
55
urethra and bladder studied by urethral pressure profil and cystometry, Proc. VIII Continence Soc. Meet.. Manchester, 1978, pp. 91-94. Pedersen, E., Torring, J. and Klemar, B., Effect of the alpha-adrenergic blocking agent thymoxamine oll neurogenic bladder and urethra, Acta Neurol. Scand., 61 (1980) 107-114. Rao, M.S., Bapna, B.C., Vaidyanathan, S. and Chary, K.S.N., Use of clonidine in the management of patients with neurogenic bladder dysfunction, Eur. Urol., 6 (1980) 261-264. Sundin, T. and Petersen, I., Cystometry and simultaneous electromyography from the striated urethral and anal sphincters and from elevator ani, Invest. Urol., 13 (1975) 40-46. Svensson, T.H., Bunney, B.S. and Aghajanian, G.K., Inhibition of both adrenergic and serotonergic neurons in brain by the alpha-adrenergic agonist clonidine, Brain Research, 92 (1975) 291-306. Tremblay, UE. and Bedard, P.J., Effect of clonidine on motoneuron excitability in spinalized rats, Neuropharmacology, 25 (1986) 41-46. Tuckman, J., Chu, D.S., Petrillo, C.R. and Naftchi, N.E., Clinical trial of an alpha-adrenergic receptor stimulant drug (clonidine) for treatment of spasticity in spinal cord injured patients. In N.E. Naftchi (Ed.), Spinal Cord Injury, SP Medical and Scientific Books, New York, 1982, pp. 133-137. Vereecken, R.L. and Verduyn, H., The electrical activity of paraurethral and perineal muscles in normal and pathological condition, Br. J. Urol., 42 (1970) 457-463. Westlund, K.N., Bowker, R.M., Ziegler, M.G. and Coulter, J.D., Descending noradrenergic projections and their spinal terminals, Prog. Brain Res., 57 (1982) 219-238. Westlund, K.N. and Coulter, J.D., Descending projections of the locus coeruleus and subcoeruleus/medial parabrachial nuclei in monkey axonal transport studies and dopamine-fl-hydroxylase immunocytochemistry, Brain Res. Rev., 2 (1980) 235-264. Yoshimura, N., Sasa, M., Ohno, Y., Yoshida, O. and Takaori, S., Contraction of urinary bladder by central norepinephrine originating in the locus coeruleus, J. Urol., 139 (1988) 423-427.
45
BRE 14596
Action of clonidine on micturitional reflexes in decerebrate cats C6sar Galeano 1, Jacques
Corcos 2, Michel Carmel 2 and Bruno Jubelin 1'*
Departments of t Physiology and Biophysics and 2Urology, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Que. (Canada) (Accepted 6 December 1988)
Key words: Decerebrate cat; Clonidine; Yohimbine; Bladder; Urethra
We explored the urodynamic action of clonidine (preferential a2-agonist) and yohimbine (preferential a2-blocker) in decerebrate cats. These animals retain catecholaminergic fibers from the complex of the locus coeruleus to the spinal cord and have synergic and faster micturition cycles than normal cats. Twenty-nine male cats were made decerebrate at intercollicular level under ether anesthesia. Voiding, vesical, urethral and blood pressures, and the EMG of the external sphincter-pelvic floor and leg muscles were studied. Preparations with the urethrovesical junction opened and closed were used. Control activity was characterized by two types of vesical pressure waves: (1) low frequency, high intensity, and (2) high frequency, low intensity. Type-2 preceded Type-1 waves. Clonidine caused: (A) reduction of Type-1 and enhancement of Type-2 Pveswaves; (B) diminution of vesical capacity; (C) facilitation of external sphincter relaxation; (D) inhibition of skeletal muscle activity; (E) systemic hypotension and bradycardia. Yohimbine inhibited clonidine's actions. When injected alone, it inhibited vesical and increased sphincteric activities. It also produced systemic hypertension and enhanced crisis of autonomic dysreflexia. The overall effect of clonidine on urodynamics in acute decerebrate cats was to bring about an active, small (normotonic) bladder with urinary frequencies. We suggest that clonidine: (1) inhibited Type-1 waves by inhibiting cellular activity in the locus coeruleus. As a result, the vesico-vesical contraction long loop reflex was abolished; (2) facilitated Type-2 waves by inhibiting inhibitory interneurons in the sacral parasympathetic center. As a result, the vesicovesical contraction short loop reflex was facilitated.
INTRODUCTION Urodynamic action of central catecholaminergic elements has been studied in humans 41-43'45,46, cats ~8"19 and rats 36,55. We have shown 19 that clonidine (a2-adrenergic agonist) can partially correct the underactive detrusor and detrusor-sphincter dyssynergia syndromes in chronic spinal cats, suggesting that the absence of descending noradrenergic (NA) fibers and the persistence of spinal a2-receptors in target neurons may play a role in vesicourethral physiopathology. Electrophysiological studies have demonstrated the inhibitory action of clonidine on the sympathetic CNS outflow to the lower urinary tract 11'31 and on pudendal nerve reflexes 14. On the whole, it has been demonstrated that bladder and external sphincter activities may be profoundly
modified by manipulating central catecholaminergic mechanisms, but our understanding of central adrenergic action on micturition remains incomplete. The catecholaminergic (CA) neurons that control the CNS are located in the brainstem, and the main centers are the locus coeruleus and subcoeruleus nuclei. They form the 'complex of the locus coeruleus' (CLC) in the dorsolateral pontine tegmentum. The C L C can influence micturition through ascending and descending efferent pathways. Ascending pathways are widespread in the brain and cerebellum, and might indirectly influence micturition through the control of motor, emotional and motivational states. Descending fibers originate in the ventral part of the C L C and innervate practically all spinal gray matter t7,37. They form two bilateral and partially crossed main pathways: the coeruleus-
* Present address: Department of Neurosciences, McMaster University, Hamilton, Ont., Canada L8N 3Z5. Correspondence: C. Galeano, DEpartement de Physiologie et Biophysique, Facult6 de M6decine, Universit6 de Sherbrooke, Sherbrooke, Que., Canada J1H 5N4, 0006-8993/89/$03.50 (~) 1989 Elsevier Science Publishers B.V. (Biomedical Division)
46 spinal, ending in the sacral parasympathetic nucleus of the pelvic nerve, and the lateral tegmental-spinal, ending in the thoracolumbar sympathetic nucleus of the hypogastric nerve 3-~'s3"54. Electrical stimulation of the LC induces vesical contractions current- and frequency-dependent, via the coeruleus-spinal pathway s-s, and the lesion of the LC produced immediate urinary retention 44. Is the CLC the 'Barrington's brainstem micturition center'? Strong evidence suggests that it plays an important role in micturition, but it is not the only brainstem nucleus to participate in the control of bladder activity. More experiments are needed to elucidate the exact role of the LC in micturition. The aim of this study was to observe cionidine's action on vesical and urethral activities in acute decerebrate cats and to infer its effects on micturition reflexes at brainstem (long loops reflexes) and sacral levels (short loops reflexes). MATERIALS AND METHODS Male cats weighing 2.5-4.5 kg were submitted to ether anesthesia, parieto-occipital craniotomy, occipital lobectomy and brainstem transection at intercollicular level. Anesthesia was discontinued and the skin was sutured with wound clips. Body temperature was controlled with a rectal thermistor (Ellab) and a heater. Blood pressure was controlled at the level of the carotid artery through an heparinized (Hepalean, OR) catheter and transducer (Bentley). A catheter was set into the femoral vein or the abdominal cavity for intravenous (i.v.) or intraperitoneal (i.p.) drug injections, respectively. For intrathecai (i.t.) administration of drugs we anesthetized the lumbar skin and dorsal muscles with lidocaine 1% (Squibb) to avoid nociceptive reflexes. A partial laminectomy was done at L 6 level and a fine catheter (o.d. = 0.3 mm) was introduced caudally in the subarachnoid space to the end of the dural sac, through a small hole in the dura mater. We used cyanoacrylate (Kraze Glue II) to fix the catheter and to seal the dura mater, avoiding rapid systemic absorption of drugs. Muscles and skin were sutured with silk thread. Two procedures to study vesicourethrai activity were used. (A) Bladder and urethra connected: the bladder was exteriorized through a suprapubic inci-
sion. A fenestrated F5 catheter was fixed through the bladder and connected to a pump (Harvard) and transducer (Bentley) for vesical pressure (Pv~,~) recording. Bladder infusion rate was 1.91 ml/min with lukewarm saline solution. This preparation allows study of urodynamics with the advantage of normal vesical emptying and urethral excitation by the periodic flow of urine during voiding. Twenty animals with micturition Pattern II, characterized by a continuous jet of urine followed by intermittent jets 2s'2~, were selected. In 4 cats a urethral catheter was added to measure urethral pressure (Pur~,)" (B) Bladder and urethra disconnected: in 9 animals, bladder neck and proximal urethra were carefully dissected keeping regional vasculature and innervation as intact as possible. Two flexible catheters (Minicath infusion set) were inserted through a hole in the proximal urethra and ligated, one towards the bladder, the other towards the urethra. The open ends were less than 1 cm from ligature. The remaining tissue between both ligatures was sectioned, so that the bladder and urethra were totally independent. Each catheter was connected through a T adaptor with separate pumps (Harvard) and transducers (Bentley). Bladder infusion rate was 1.91 ml/min until a regular rhythm of vesical waves was present. Infusion was then stopped or was reduced to 0.382 ml/min. Voiding was impossible. The vesicovesical contraction reflex was activated without the interplay of urethrovesical reflexes generated by the periodic transit of urine in the urethra. The urethra was perfused at a rate of 0.191 or 0.382 ml/min, constant in each cat, and the resistance to flow was approximately estimated by the Pur," This constant, slow perfusion rate did not elicit urethral reflexes. These techniques are modified versions of previously published m e t h o d s 2°'23'27"29. The E M G of the external sphincter-pelvic floor striated muscles (EMGes) was studied with coaxial (Kopf) or parallel (Grass) needle electrodes in a juxta-urethrai, subpubic site that showed intense activity when bulbocavernosus reflexes were activated. The E M G of hind leg muscles (EMGhl) was obtained with parallel Grass needle electrodes. All the inputs were connected to a Grass D polygraph. Urine flow (UF) was visually controlled and registered on records with an ON-OFF switch. We studied the cystosphincterograrn, including P,,~,
47 P ..... UF and EMGs. The urodynamic study is started at least 1 h following interruption of anesthesia. The following drugs were administrated: (a) clonidine hydrochloride (CLON) (Boeringer Ingeheim or Sigma) as a preferential a2-agonist that crosses the blood-brain harrier (BBB), in doses of 0.020.12 mg/kg i.v. or i.p., and 3-5 /~g/kg, i.t.; (b) yohimbine hydrochloride (YOH) (Welker Lyster or Sigma) as a preferential a2-antagonist that crosses the BBB, in doses of 0.2-1 mg/kg, i.v. or i.p., and 30 ltg/kg, i.t.; (c) trimethaphan camsylate (Arfonad, Roche) in doses of 0.5-0.7 mg/kg, i.v. We used the i.v. route to get fast and high blood concentration of drugs, the i.p. to get a slower, more progressive increase of blood drug concentration, reducing unspecific receptor stimulation or inhibition of other than a2-receptors, and the i.t. to get direct, isolated CNS action. Descriptive statistics (mean and S.D.) and t-tests for independent and dependent samples were done using the MacSS StatSoft program. RESULTS
Behavior Intercollicular decerebration produced the classic 'rigidity' characterized by stiffness of extensor muscles of the 4 limbs and clenching of the jaw. There was intense exaggeration of stretch reflexes. Animals were in coma. Breathing and circulation were approximately normal. CLON reduced rigidity. YOH increased rigidity and induced or exaggerated locomotion-like movements. When injected rapidly, cats died after a rigidity crisis.
Neurourodynamics Control Preparation A. In all animals, (n = 20) bladder contractions were associated with relaxation of sphincters (evaluated by reduction of the EMGes activity) and voiding with repeated pelvic floor contractions (Pattern II micturition) 25'28 (Figs. 1-3). Vesicovesical contraction (short and long loops), vesicourethral relaxation, urethro-urethral contraction, and urethrovesical contraction reflexes were acting (for a brief description of these reflexes see2°).
Preparation B. In all animals (n = 9) Pattern I micturition 25'zs was observed, characterized by isolated vesical contractions without pelvic floor contractions (Fig. 4). Resistance to urethral flow (P,ra) was variable, showing small increases or decreases. EMG activity decreased during Pves waves in all animals. Because there was no voiding, the urethrourethral contraction and urethrovesical contraction reflexes were not activated. Two types of Pvc~ waves were observed (Table I, control): low-frequency, high-intensity and longduration, triggered at a bladder volume of 25 ml or more (Type 1), and fast-frequency, low-intensity and short-duration, triggered at a bladder volume of 5 ml or more (Type 2). In preparation A, Type-1 waves had a first regular period, followed by a series of superimposed irregularities associated with bulbocavernosus contractions, characteristic of Pattern-II micturition. These complex high-intensity waves were preceded by low intensity Type-2 waves (Fig. 1). In preparation A, Type-1 and Type-2 waves were significantly different (P < 0.001) (Table I). In preparation B, only regular Type-1 waves (Table II, control) were observed (Fig. 4). Type-1 waves in preparation B, were more frequent, intense and of shorter duration than Type-1 waves in preparation A without urethral catheter (P < 0.001). They had a small difference in intensity (P < 0.05) with Type-1 waves in preparation A. Frequency and duration were significantly different (P < 0.001) when a urethral catheter was used (see control, Tables I and n). Clonidine Preparation A. Following CLON administration at doses higher than 0.02 mg/kg, i.v. or i.p., total but transitory inhibition of Type-1 Pve~ waves, significant facilitation or increase of Type-2 Pve~ waves (Table I, clonidine), and inhibition of striated muscle activity were observed. In preparation A with a urethral catheter - - which augments urethral resistance - the increase in intesity (P < 0.001) and duration (P < 0.001) of Type-2 waves was more significant than in preparations without urethral catheter. This effect was present for 1-2 h (n = 6) using smaller doses (0.02-0.03 mg/kg) and was still present 7 h (n = 3) following administration of the highest doses of CLON (0.10-0.12 mg/kg). Doses of 0.05-0.10 mg/
48
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Fig. I. Action of clonidine. Preparation A (bladder and urethra connected). In all figures, injection of drugs is marked by a textured bar; injection starts at the beginning and finishes at the end of the bar. Control: note Pattern-II micturition: a first period with a continuous urine jet and sphincter relaxation, followed by a second period of irregular, high Pve~wave, bulbocavernosus contractions and intermittent jets of urine. This is not a detrusor-sphincter dyssynergia, but a normal, essential period for total bladder emptying. At the end of the Pw~ wave the external sphincter (EMGes) contracts. Clonidine: time scale (abscissa) changed. Note the high-frequency, low-intensity Pves waves (Type 2), starting the voiding cycle. They slightly increase in intensity and are followed by high-intensity, low-frequency Pw~ waves (Type 1), indicated by an asterisk. Note the increase in intensity of Type-2 and reduction of Type-/waves. Facilitation of Type-2 waves produces a paired pattern; after 30 min, typical single activity associated with voiding is seen. After 60 min, the action of this weak dose of clonidine is still present. Note the progressive reduction of EMG activities and long-lasting hypotension.
kg, i.v., were used to test the blocking effect of Y O H (n = 8). l.t. administration ( 3 - 5 /~g/kg) (n = 3) p r o d u c e d u r o d y n a m i c actions similar to those of the i.v. route. Control i.t. injections of vehicle alone p r o d u c e d a small and irregular response for 1-2 min when injected rapidly; with slow administration, no response was observed. I.t. injected volume was 0 . 1 - 0 . 2 ml. Note in Figs. 1 and 2 the progressive inhibition of Type-1 waves, waning of Pattern-II micturition, reduction o f vesical capacity, increased
intensity of Type-2 waves, urinary frequency and intense reduction o f E M G activity. N o urine retention was observed. I.p. injection elicited effects similar to that of i.v., but they were slower to appear. U r o d y n a m i c effects were always associated with systemic hypotension and bradycardia. I.t. administration of C L O N p r o d u c e d small cardiovascular and striated muscle actions and intense urodynamic responses (Fig. 5). Preparation B. Large Type-1 Pves waves were
49 TABLE I Vesical waves
Preparation A. Values are mean + S.D. With urethral catheter (n = 4)
Without urethral catheter (n = 10) Freq. (rain)
Int. (ram Hg)
Dur. (s)
Freq. (min)
Int. (mrn Hg)
Dur. (s)
Control Type-1 waves Type-2 waves
0.241 + 0.223 2.300 + 0.888
38.740+ 8.409 7.000 + 1.414
57.100+ 9.960 10.100+ 2.767
0.397 + 0.080 2.250 + 0.500
64.000+ 7.528 4.250 + 1.258
66.000+ 7.528 10.750+ 2.217
Clonidine Type-1 waves Type 2-waves
0.000 + 0.000 1.900 + 0.358*
0.000 + 0.000 0.000+ 0.000 11.500 + 2.168" 20.000+ 1.673"
0.000 + 0.000 2.125 + 0.299
0.000 + 0.000 35.250+ 6.752
0.000 + 0.000 21.00+ 1.414
*n=6.
totally inhibited for a short time, allowing Type-2 waves to a p p e a r (Table II, clonidine). Finally, Type-1 waves were re-established (Fig. 4). Yohimbine Preparation A . Low doses (0.2-0.4 mg/kg, i.v.) of
Y O H antagonized C L O N effects, restoring micturition p a t t e r n II and striated muscle activity (n = 5) (Fig. 2). A t high doses (0.5-1 mg/kg, i.v.) it inhibited vesical activity (n = 3) (Fig. 3). In Fig. 3, we a d m i n i s t e r e d tubocurarine before Y O H to eliminate Y O H striated muscle action enhancement. Note the change from Pattern-II to Pattern-I micturition when bulbocavernosus contractions were blocked by tubocurarine; b l a d d e r activity was inhibited. A t doses of 1 mg/kg i.v., Y O H facilitated crises of rigidity when no neuromuscular blocking drug was used. By i.t. route Y O H (30 ktg/kg) inhibited C L O N action and b l a d d e r activity (n = 3) (Fig. 5). Preparation B. A t low doses (0.2-0.5 mg/kg, i.v.) Y O H briefly inhibited b l a d d e r activity for a short
time and enhanced bulbocavernosus and urethrovesical contraction reflexes (n = 4). A t high doses (0.5-1 mg/kg, i.v.) longer b l a d d e r inhibition was observed, followed by a long-lasting period of bulbocavernosus reflex enhancement (n = 2) (Fig. 4). Ganglionic blockade Trimethaphan (0.5-0.7 mg/kg, i.v.) p r o d u c e d ganglionic b l o c k a d e and inhibited Type-1 and Type-2
activity. Fig. 6 shows inhibition of Type-2 waves after administration of C L O N (n = 3). DISCUSSION This study on acute, d e c e r e b r a t e cats showed the presence of two types of vesical waves and a differential action of C L O N on these vesical activities; inhibition, facilitation. A r e Pves waves neurogenic or myogenic? O u r experiments using the ganglionic blocking agent t r i m e t h a p h a n confirmed previous reports 34'35 showing that both types of
TABLE II Vesical waves
Preparation B. Values are mean + S.D. Control (n = 9)
Clonidine (n = 5)
Freq. (rain)
Int. (ram Hg)
Dur. (s)
Freq. (min)
Type 1
0.926 + 0.108
75.111+ 8.238
35.444+ 3.644
0.000 + 0.000
0.000 + 0.000
0.000 + 0.000
Type 2
0.000 + 0.000
0.000 + 0.000
0.000+ 0.000
2.960 + 0.336
15.200+ 0.837
16.400+ 1.949
Int. (ram Hg)
Dur. (s)
51 CONTROL EmGes
~::;
. : ':
-
, -"
~, - ~ "
•
, _~j,
i
IO0[mrnHg
PURA
PVES
,oo[ 0/
OI
T U B O C U R A R I n E 1 mg/kg/tv It
YOHImBInE
,
h
1rng/kg/lv
m 1
rain
Fig. 3. Action of clonidine, tubocurarine and yohimbine. Preparation A. Note the typical Pattern-II voiding. After tubocurarine, the striated muscle activity disappears and Pattern-I micturition is observed. Yohimbine inhibits vesical activity.
vesical waves were of neurogenic origin. Is bladder activity organized at central or peripheral level? The use of the i.t. route showed centrally mediated CLON urodynamic actions, as previously reported 26" 36. In addition, it has been demonstrated that CLON affected the urethral reflex response elicited by stimulation of the pudendal nerve, but had no effect on the direct responses elicited by stimulation of the peripheral end of the same cut pudendal nerve 14. Urodynamic central actions of CLON are well demonstrated, but the exact mechanism in brainstem, posterior, intermediate or anterior horns, motoneurons or interneurons, remains to be elucidated. Peripheral vesical and urethral actions of
CLON were described in in vitro experiments 1,36. In whole animal experiments, peripheral CLON action might affect vesical performance (for example, a small change in Pves intensity), but it seems to have no importance in the central regulation of micturition reflexes. How can we interpret CLON's actions in the context of vesical reflexes? Vesical distension produces reflex vesical contraction. This is accomplished by activation of two reflex arcs: the long loop of the brainstem vesicovesical contraction reflex 2,3 and the short loop of the spinal vesicovesical contraction reflex 7,12. Progressive vesical distension elicited two types of Pves waves: slow-frequency,
52 ioomr*mg
o~ r ~
C LOFI1DiD, E <-.__J
,,
:,~'.,;
~,
. ~.~-_J
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
:)olmmHg 0
I ~
~ill[lllllillllilll IIIIIBIIIIn IIlIuIIIIIIIIIIIIIllllllIIIIInlllullnlILIl i l ~
I I
0 6 rng/Kgllv
tn,t
YOHImBIFIE
f',
i~',
o 8 mg/Kg/iv
Fig. 4. Action of clonidine and yohimbine. Preparation B (bladder and urethra separated). Note the Pattern-I micturition before the injection of clonidine (textured horizontal bar), Clonidine inhibits the large Pvcs waves (Type 1). Smaller, faster waves (Type 2) appear briefly for about 23 min, and then, Type-1 waves reappear (records are continuous). A first injection of 0.5 mg/kg, i.v., of yohimbine (injection was done 5 min before the record) radically changes bladder and urethral activities. The sharp Pu,, waves correspond to bulbocavernosus reflexes. They are followed by bladder contractions (urethrovesical contraction reflex). A second injection of yohimbine (0.8 mg/kg, i.v.) (illustrated) inhibits the large P,~ waves and again the small, fast Type-1 P,es waves appear for about 27 min, before the activity becomes similar to that of the first injection record. This activity persists for more than 1 h. Bladder volume increases from 30 to 70 ml.
high-intensity, long-duration waves, triggered at large b l a d d e r volume (Type 1), and fast frequency, small intensity, short duration waves, triggered at low b l a d d e r volume (Type 2), as previously r e p o r t e d
in anesthetized rats 34'35. We suggest that progressive b l a d d e r distension triggers first the spinal vesicovesical contraction reflex, which produces small Type-2 waves; then, this activity triggers the brain-
53
stem vesicovesical contraction reflex, responsible for intense Type-1 waves. The long loop function would be fundamentally the multiplication or amplification of the spinal reflex6"3z. The integrative center of the long loop reflex is in the brainstem, probably including the complex of the LC. For this reason, bladder motility is modified by drugs that change CLC activity. CLON inhibits LC activity~-"~JT" 22.24.49; as a result, it blocks the brainstem vesicovesical contraction reflex and reduces Type-1 Pves waves. On the other hand, it increases the activity of the spinal vesicovesical contraction reflex m. How can CLON increase the spinal vesicovesical contraction reflex? In general, CLON action on spinal neurons is inhibitory37 and noradrenaline inhibits firing of preganglionic neurons 26. The facilitation of the spinal vesicovesical contraction reflex probably involves inhibition of a negative feedback controlling the gain of the reflex (an inhibition of inhibitory
interneurons), and/or suppression of the sympathetic outflow to the periphery. The final balance between both actions in preparation A, with opened urethrovesical junction, was a very active bladder with small vesical capacity, intense, frequent contractions of spinal origin and urinary frequency. When the urethrovesical junction was ligated and no voiding was possible (preparation B), bladder distension was progressive and continuous producing intense activation of brainstem centers. Under these circumstances, the inhibition of the LC elicited by CLON, blocked the large waves and allowed the spinal waves to appear for a short time. Then, the continuous, progressive bladder distension overcame CLON inhibition and brainstem Type-1 activity reappeared. YOH inhibited CLON urodynamic effects and when injected alone or in high doses, it antagonized sacral parasympathetic activation, eliminating or sharply reducing bladder activity as pre-
CODTROL
501rnmHg uF
, .1 ! Fl!
CLODIDIDE
YOHImBIDE
DteSg •
5 .glkg/IT
30 lag/kg/IT
~
0 ITIIn. I
Fig. 5. Action of i.t. clonidine and yohimbine. Preparation A. Control: note the typical Pattern-II micturition with Type-1 Pves waves preceded by Type-2 waves. Administration, i.t., of clonidine inhibited Type-1 Pve~ waves, enhanced Type-2 waves and produced dribbling. I.t. yohimbine briefly inhibited bladder activity.
54
CLOFIIDIFIE
3 lag/kg/IT
TRIlTIETAPHAFI
o.s m o / k g / l v
2 0 0 ~nrnHg
BP
Pves
o 5O "nmHg
o D~c sE~ 4
13q I F1
~
Fig. 6. Action of trimethaphan, preparation A. I.t. administration of clonidine induced rhythmic Type-2 Pve~ waves. I.v. trimethaphan blocked these vesical waves and reduced blood pressure. viously demonstrated in spinal cats 19. The mechanisms is probably indirect, by disinhibiting negative feedback and increasing sympathetic outflow from the CNS, because vesical contractions elicited by electrical stimulation of the locus coeruleus are not inhibited by i.t. Y O H 55. Passage of urine through the urethra during voiding stimulates urethral mechanoreceptors and triggers the urethrovesical contraction reflex. This is synergistic with the vesicovesical contractor reflex and allows the detrusor to continue contraction when bladder volume diminishes. The urethrovesical contraction reflex has brainstem and spinal loops 3-5. In preparation A, the reflex was normal; in preparation B, the reflex was absent and voiding was impossible. It is difficult to specify CLON action on this reflex in preparation A. Inhibition of the brainstem loop is probably compensated by enhancement of the short loop. Passage of urine through the urethra during voiding still elicited other reflexes, such as urethrourethral contraction and bulbocavernosus reflexes 2°' 21. These reflexes produce a sharp Pura increase and trigger the urethrovesical contraction reflex. All these contraction reflexes (vesicovesical, urethrovesical, urethro-urethral and bulbocavernosus) sustain Pattern II micturition in cats. The urethrourethral contraction reflex was normal in preparation A and absent in preparation B. When present, it was intensely inhibited by CLON. This drug inhibits striated muscle hyperactivity in decerebrate or spinal animals and spastic patients 19'3°'3s-4°'5°'51. Bulbocavernosus and urethro-urethral contraction reflexes were inhibited and Phase II micturition pattern vanished. CLON also inhibits pudendopudendal reflexes ~4, which are related to urethro-
urethral contraction and bulbocavernosus reflexes. Humans do not have Pattem-II micturition and the urethro-urethral reflex is observed during the filling phase as an emergency reflex that guards continence 21. The increase of bladder volume and/or pressure elicits another fundamental voiding reflex: the vesico-urethral relaxation reflex that opens sphincters 3-5"15"16"21"32.Relaxation of skeletal muscles reduces urethral resistance to flow and facilitates voiding. This reflex was not substantially modified by CLON. During the first period of continence, the filling of the bladder is maintained by passive factors, depending on the bladder neck structure. Later the vesicourethral contraction reflex is activated assuring urethral closure 13"21'29"32'48'52. CLON inhibits the striated component of this reflex. Moreover, the sympathetic inhibition decreases sphincteric smooth muscle tonus, so that even small Pves waves elicit voiding. CONCLUSIONS
In unanesthetized acute decerebrate cats, i.v., i.p. and i.t. administration of clonidine produces the following urodynamic effects: (1) it inhibits the low-frequency, large Pves waves (Type 1), probably by inhibiting the brainstem long loop of the vesicovesical contraction reflex; (2) it inhibits Pattern-II feline micturition, probably by inhibiting the urethro-urethral contraction and bulbocavernosus reflexes; (3) it facilitates the fast frequency, small Pves waves (Type 2), probably by inhibiting negative feedback loops linked to the spinal short loop vesicovesical contraction reflex and/or the sympa-
55 thetic outflow from the CNS; (4) it reduces vesical capacity and produces urinary frequency; (5) it enhances relaxation of urethral sphincters. The final effect is a small, very active bladder with urinary frequency. Besides these urodynamic effects, CLON produces striated muscle relaxation, hypotension and bradycardia. YOH antagonizes all CLON's effects. When injected alone, it produces bladder inhibition, hypertension, tachycardia and rigidity crisis. REFERENCES 1 Andersson, K.E., Mattiasson, A. and Sjogren, C., Electrically induced relaxation of the noradrenaline contracted isolated urethra from rabbit and man, J. Urol., 129 (1983) 210-214. 2 Barrington, J.F.J., The nervous mechanism of micturition, Q. J. Exp. Physiol., 8 (1914) 33-71. 3 Barrington, J.EJ., The relation of the hind-brain to micturition, Brain, 44 (1921) 23-53. 4 Barrington, J.F.J., The component reflexes of micturition in the cat. Parts I and II, Brain, 54 (1931) 117-188. 5 Barrington, J.F.J., The component reflexes of micturition in the cat. Part III, Brain, 64 (1941) 239-243. 6 Bradley, W.E., Micturition reflex amplification, J. Urol., 101 (1969) 403-407. 7 Bradley, W.E. and Teague, C.T., Spinal cord organization of micturition reflex afferents, Exp. Neurol., 22 (1968) 504-516. 8 Byrum, C.E., Stornetta, R. and Guyenet, P.G., Electrophysiological properties of spinally-projecting A5 noradrenergic neurons, Brain Research, 303 (1984) 15-29. 9 Cedarbaum, J.M. and Aghajanian, G.K., Noradrenergic neurons of the locus coeruleus: inhibition by epinephrine and activation by the alpha-antagonist piperoxan, Brain Research, 112 (1976) 423-429. 10 Cedarbaum, J.M. and Aghajanian, G.K., Catecholamine receptors on locus coeruleus neurons: pharmacological characterization, Eur. J. Pharmacol., 44 (1977) 375-385. 11 De Groat, W.C. and Douglas, J.W., The effects of L-5-hydroxytryptophan (5-HTP) and clonidine on central sympathetic and parasympathetic reflex pathways to urinary bladder of the cat, Fed. Proc., 34 (1975) 795. 12 Denny Brown, D. and Robertson, E.G., On the physiology of micturition, Brain, 56 (1933) 149-190. 13 Downie, J.W. and Awad, S.A., The state of urethral musculature during the detrusor areflexia after spinal cord transection, Invest. Urol., 17 (1979) 55-59. 14 Downie, J.W. and Bialik, G.J., Clonidine suppresses somatic and viscerosomatic reflex activity evoked on the pudendal nerve in cats, Neurourol. Urodyn., 3 (1987) 141-143. 15 Edvarsen, P., Nervous control of urinary bladder in cats, I. The collecting phase, Acta Physiol. Scand., 72 (1968a) 157-171. 16 Edvarsen, P., Nervous control of urinary bladder in cats. II. The expulsion phase, Acta Physiol. Scand., 72 (1968) 172-182. 17 Fung, S.J. and Barnes, C.D., Locus coeruleus control of
ACKNOWLEDGEMENTS
The authors are grateful to Mr. Pierre Gagn6 and Miss Ann Graillon for their efficient help in several experiments. We also wish to express our thanks to Boering Ingeheim Canada Ltd. and Welker Lyster Lt6e. for their respective donations of clonidine and yohimbine.
spinal cord activity. In C.D. Barnes (Ed.), Brainstem Control of Spinal Cord Function, Academic Press, New York, 1984, pp. 215-255. 18 Gajewski, J., Downie, J.W. and Awad, S.A., Experimental evidence of a central nervous system site of action in the effect of alpha-adrenergic blockers on the external sphincter, J. Urol., 133 (1984) 403-409. 19 Galeano, C., Jubelin, B., Carmel, M. and Ghazal, G., Urodynamic action of clonidine in the chronic spinal cat, Neurourol. Urodyn., 5 (1986) 475-492. 20 Galeano, C., Jubelin, B., Germain, L. and Guenette, L., Micturitional reflexes in chronic spinalized cats. The underactive detrusor and the detrusor-sphincter dyssynergia, Neurourol. Urodyn., 5 (1986) 45-63. 21 Garry, R.C., Roberts, T.D.M. and Todd, J,K., Reflexes involving the external urethral sphincter in the cat, J. Physiol. (Lond.), 149 (1959) 653-655. 22 Geyer, M.A. and Lee, E.H.Y., Effects of clonidine, piperoxane and locus coeruleus lesion on the serotoninergic and dopaminergic systems in raph6 and caudate nucleus, Biochem. Pharmacol., 33 (1984) 3399-3405. 23 Girado, J.M. and Campbell, J.B., The innervation of the urethra of the female cat, Exp. Neurol., 1 (1959) 44-64. 24 Guyenet, P.G., The coeruleus-spinal noradrenergic neurons: anatomical and electrophysiological studies in the rat, Brain Research, 189 (1980) 121-133. 25 Hassouna, M., Abdel-Rahman, M., Galeano, C., Lamarche, J. and Elhilali, M.M., La physiologie v6sico-ur6trale pendant la continence et la miction chez le chat, J. Urol., 89 (1983) 201-206. 26 Hisamitsu, T. and De Groat, W.C., The depressant effects of clonidine applied intracerebroventricularly and intrathecally on the sympathetic outflow to the urinary bladder of the cat, Pharmacologist, 25 (1983) 161. 27 Jonas, U. and Tanagho, E.A., Studies on vesicourethral reflexes. I. Urethral sphincteric responses to detrusor stretch, Invest. Urol., 12 (1975) 357-373. 28 Jubelin, B., Galeano, C., Ladouceur, D., Lemaire, S. and Elhilali, M.M., Effect of enkephalin on the micturition cycle of the cat, Life Sci., 34 (1984) 2015-2027. 29 Kiruluta, H.G., Downie, J.W. and Awad, S.A., The continence mechanisms: the effect of bladder filling on the urethra, Invest. Urol., 18 (1981) 460-465. 30 Knutsson, E., Martensson, A. and Gransberg, L., Antiparetic and antispastic effects induced by tizanidine in patients with spastic paresis, J. Neurol. Sci., 53 (1982) 187-204. 31 Krier, J., Thor, K.B. and De Groat, W.C., Effects of clonidine in the lumbar sympathetic pathways to the large
56
32 33
34
35
36
37
38 39
40 41
42
43
44
45
intestine and urinary bladder of the cat, Eur. J. Pharrnacol., 59 (1979) 47-53. Kuru, M., Nervous control of micturition, Physiol. Rev., 45 (1965) 425-494. Loewy, A.D., Saper, C.B. and Baker, R.P., Descending projections from the pontine micturition center, Brain Research, 172 (1979) 533-538. Maggi, C.A., Santicioli, P. and Meli, A., Sympathetic inhibition of reflex activation of bladder motility during filling at a physiological-like rate in urethane anaesthetized rats, Neurourol. Urodyn., 4 (1985) 37-45. Maggi, C.A., Santicioli, E and Meli, A., The effect of hexamethonium on the distension-induced contractile activity of the rat bladder: evidence for the existence of a spinal 'short-loop' vesico-vesical reflex in rats, Neurourol. Urodyn., 5 (1986) 403-410. Maggi, C.A., Santicioli, P., Furio, M. and Meli, A., Dual effects of clonidine on micturition reflex in urethane anesthetized rats, J. Pharmacol. Exp. Ther.. 235 (1985) 528-536. Marshall, K.C., Catecholamines and their actions in the spinal cord. In R.A. Davidof (Ed.), Handbook of the Spinal Cord, Vol. 1, Dekker, New York, 1983, pp. 275-327. Maynard, EM., Early clinical experience with clonidine in spinal spasticity, Paraplegia, 24 (1986) 175-182. Naftchi, N.E., Functional restoration of the traumatically injured spinal cord in rats by clonidine, Science, 217 (1982) 1042-1044. Nance, P.W., Shears, A.H. and Nance, D.M., Clonidine in spinal cord injury, Can. Med. Assoc. J., 133 (1985) 41-42. Nordling, J., Meyhoff, H.H. and Christensen, N.J., Effects of clonidine (Catapresan) on urethral pressure, Invest. Urol., 16 (1979) 289-291. Nordling, J., Meyhoff, H.H. and Christensen, N.J., Influence of sympathetic tonus and plasma noradrenaline on urethral pressure, Scand. J. Urol. Nephrol., 15 (1981) 1-6. Nordling, J., Meyhoff, H.H. and Hald, T., Sympatholytic effect on striated urethral sphincter, Scand. J. Urol. Nephrol., 15 (1981) 173-180. Osumi, Y., Oishi, R., Fujiwara, H. and Takaori, S., Hyperdipsia induced by bilateral destruction of the locus coeruleus in rats, Brain Research, 86 (1975) 419-427. Pedersen, E., Torring, J. and Klemar, B., Effect of the alpha-adrenergic blocking agent thymoxamine on the
46
47
48
49
50
51
52
53
54
55
urethra and bladder studied by urethral pressure profil and cystometry, Proc. VIII Continence Soc. Meet.. Manchester, 1978, pp. 91-94. Pedersen, E., Torring, J. and Klemar, B., Effect of the alpha-adrenergic blocking agent thymoxamine oll neurogenic bladder and urethra, Acta Neurol. Scand., 61 (1980) 107-114. Rao, M.S., Bapna, B.C., Vaidyanathan, S. and Chary, K.S.N., Use of clonidine in the management of patients with neurogenic bladder dysfunction, Eur. Urol., 6 (1980) 261-264. Sundin, T. and Petersen, I., Cystometry and simultaneous electromyography from the striated urethral and anal sphincters and from elevator ani, Invest. Urol., 13 (1975) 40-46. Svensson, T.H., Bunney, B.S. and Aghajanian, G.K., Inhibition of both adrenergic and serotonergic neurons in brain by the alpha-adrenergic agonist clonidine, Brain Research, 92 (1975) 291-306. Tremblay, UE. and Bedard, P.J., Effect of clonidine on motoneuron excitability in spinalized rats, Neuropharmacology, 25 (1986) 41-46. Tuckman, J., Chu, D.S., Petrillo, C.R. and Naftchi, N.E., Clinical trial of an alpha-adrenergic receptor stimulant drug (clonidine) for treatment of spasticity in spinal cord injured patients. In N.E. Naftchi (Ed.), Spinal Cord Injury, SP Medical and Scientific Books, New York, 1982, pp. 133-137. Vereecken, R.L. and Verduyn, H., The electrical activity of paraurethral and perineal muscles in normal and pathological condition, Br. J. Urol., 42 (1970) 457-463. Westlund, K.N., Bowker, R.M., Ziegler, M.G. and Coulter, J.D., Descending noradrenergic projections and their spinal terminals, Prog. Brain Res., 57 (1982) 219-238. Westlund, K.N. and Coulter, J.D., Descending projections of the locus coeruleus and subcoeruleus/medial parabrachial nuclei in monkey axonal transport studies and dopamine-fl-hydroxylase immunocytochemistry, Brain Res. Rev., 2 (1980) 235-264. Yoshimura, N., Sasa, M., Ohno, Y., Yoshida, O. and Takaori, S., Contraction of urinary bladder by central norepinephrine originating in the locus coeruleus, J. Urol., 139 (1988) 423-427.