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519 Effect of hydrochlorothiazide on renal electrolyte gradient in glucose diuresis and diabetes insipidus
156
Abstracts
depolarized as well as in the polarized smooth muscle the presence of Ca is found to be essential for the initiation of contraction. The contractile responses of ACh and the r-rffcct of adrenaline show a \ cry similar Ca dependence. Thus, in the depolarized rat seminal vesicle, the isometric responses to ,2Ch and adrenaline dcclinc at the same rate when Ca is rrmoved from the bathing fluid and are restored at the same rate when Ca is reintroduced. Calcium itself inducrs a slow sustained contraction c;f the depolarized smooth musclc.~~’ However, ACh and adrenaline added on top of a Ca contraction produce a rapid further increase in tension, cvcn in a preparation maximally contracted to Ca. The contractile effect of Ca is strongly antagonized by the p-effect of adrenaline. In the depolarized rat uterus a substantial inhibition of the Cainduced contraction is produced by 10 O adrenaline and isoprenalinc. The experiments can be fitted into the hypothesis that Ca is a” early link in the initiation of muscular contraction. ACh and the a-effect of adrenaline, although obviously acting on different receptors since they are antagonized by dilrerent antagonists, may have a later reaction step in common, a mobilizing of intracellular Ca.
1. F,VANS, SCHII.D and THEXWF (19581, 3. P/ysiol., 143, 474. 2. EDMAN and SCMLD (1961), 3. PhyJiol, 155, 1OP.
517 Sodium Exchange in Smooth GO~DFORD (United Kingdom).
Muscle.
I’. .J.
It has been shown that a steady state was reached whrn pieces of guinea-pig taenia coli were set up in oxygenated Krebs’ solution at 35”C, and that the ?;a content, K content and inulin space of the smooth muscle became constant.“’ Nearly all the Na in the tissue exchanged with a half-life of 0.5 min when the bathing solution had been labelled with TaNa, and this exchange was too rapid to permit any resolution into intracellular and cxtraccllular components. Other pieces of taenia were equilibrated in a normal Ringer’s solution and then transferred to one in which all the Na salts had been replaced by Li; the Na again washed out of the tissue with a” initial half-life of 0.5 min but a portion remained in the muscle during the one hour immersion in the Li Ringer. As it was found@) that the Na content of the taenia approached that of the rxtrrnal bathing solution after equilibration of the muscle al 4’C. the experiment in Li solution was repeated at that temperature and the proportion of “nnexchangeable Na was then much greater. It is suggested that the Na which remained in the tissue in the presence of Li was intracclhtlar. The low content of bound Na at 35°C would then indicate a low intracellular concentration, which, . approachrd the concentration I” tne however,
of
Papers external solution at 4’C. This observation may tx used to interpret the normally very rapid Na cxchange, and to resolve its separate components.
1. GOODFORD,
3.
P. J.
and
HERHANSEN, K.
(1960‘.
Physiol., 153, 29P.
2. GOODFORD and NARROD.
Unpublished.
518 Action
of Cardiac Glycosides Muscle. T. GODFRAIND and
on a Smooth A.
GODFKAI.~I)
DE BECKER (Congo). A piece of guinea-pig ileum was used and bathed by a” oxygenated Tyrode solution. Contractions were recorded with a” isotonic frontal levw. Sweral cardiotonics have been studied (digitoxin. ouabain, k-strophanthoside, 5 x lo-* to 5 x 10 3 v/w). All cause a contraction of the muscle: relaxation appears in the same solution. There is no relation between the dose and the height of contraction. This is a tachyphylactic action. The action of these drugs on cholinergic OLhistaminrrgic muscle stimulation appears to lx biphasic. First we observed a potentiation of the effects of acetylcholine and histamine. This potcntiation occurs simultaneollsly with the contractile responsr of the ileum to the glycoside and appear\ only whrn contraction is produced by chemical transmitters. When the intestine is stimulatrcl coaxially, the phcnornenon still appears but in the prcsencc- of atropine, no potentiation is evoked. This first phase is followed by a competitive inhibition of the effects of agonists. Several factors are concerned with this inhibitory action: the concentration of glycoside in the bath, the time of contact before contraction and the contractile activity of the muscle itself. Graphical representation of thest factors give a typical saturation curve. There is an obvious parallelism between these data and the influence of the same factors on ion exchanges. Another point of similarity is the action of desoqcorticosterone. This drug which depresses the elrcct\ of glycosides on ion movements, reduces also thcilaction against and competitive acctylcholim histamine. 519 Effect
of Hydrochlorothiazide on Renal Electrolyte Gradient in Glucose Diuresis and Diabetes Insipidus. J. I’. BAER, .A. 1.. BROOKS and K. M. NOLL (U.S..%.).
In edematous patients. hydrochlorothiazide produces saluresis and estcnsive water diuresis. In diabetes insipid&, on the other hand, thiazide\ actually dilninish urine flow \vhile rendering the urine more hypertonic. The present experiments were designed to relate these actions of hydrorhlorothia&e to the magnitude of the clwtrolyte gradient in the kidney. Hyclrorhlorothiazidc ( IOO mg/kg/I.V.) did not affect the rrnal elertrolvte aradient in uninfusetl Y
Abstracts of Papers dogs. The infusion of 5 per cent glucose at to ml/ min alone obliterated the renal electrolyte gradient that is present in normal uninfused dogs. Hy-drochlorothiaLide did not restore the gradient in the glucose-infused dogs. In rats vith experimental diabetes, a marked gradient occurred, the sodium content increasing from ;o mcq/kg \vct wt. in the cortex to :joo meq/kg \vet \vt. in the papilla. Administration of hvdrochlorothiazide for 3 days (45 mg/kg orally in di;-ided doses) decreased urine tlow and \vatcr intake promptly : electrolyte excretion decreased more slowly. The sodium gradient was minimally atIectec1 by the llydrochtorothiazide treatment.
520 The Role of Hyaluronidase Antidiuretic Hormone. (U.S.S.R.).
in the Action of A. G. GINETZINSKY
In the state of dehydration the urine of all tcrrestrial vertebrates contains hyaluronidase. Enzymatic activity of the urine drops to the zero level after water loading when thr secretion of XDH i5 inhibited. \Vhcn suitable experimental conditions excluding electrolyte and dilution effect are created the correlation between hyaluronidase activity of the urine and the extent of diuresis is maintained. Hyaluronidase inhibitors when administrated directly into the renal artery increase dim&. This effect appears on the side of the injection only. If the structures producing antidiuretic hormone are destroyed hyaluronidase disappears from the urine, but after pitressin injection the urine reacquires fcrmmtative activity. Ily means of the stop flow method, it was found that hyaluronidase appears in the urine produced by the distal parts of the nephron. Proximal urine enzyme. Cytological and histocontains no chemical investigations showed that rcnal rpithelium acted upon by ADH secretes a substance containing protein. The intercellular cement and the basement membrane of the collecting ducts and of the distal parts of the nephron contain hyaluronic acid. The XDH by means of hyaluronidase effect is produced liberation. The enzyme depolymerizes hyaluronic acid which makes the tubule wall waterproof. its permeability increases. The Accordingly, osmotic free water then is reabsorbed and antidiurrsis occurs. 521 Renal Transport ing Hypothesis.
of Organic Anions: A UnifyA. DESPOPOULOS (U.S.A.).
;\ctive renal tubular excretion of organic anions has been examined in an attempt to define the nature of the physico-chemical interaction between transported substrates and a postulated receptor in Comparison of more than 150 organic renal cells. anions permits tentative description of a general molecular structure which defines substrate specificity of the transport system. Intramolecular
157
components which appear to be essential for transport include an unsaturated oxygen group (-C:O; --S:O) and an ionic function (-COOH: -SO,OH: -SO,NH-). A three-point interaction with the receptor can be satified by formation of a hydrogen bond at the unsaturated oxygen (-C :O : -S :0) and both a hydrogen bond and an ionic bond at the anionic group. These postulates are invoked to account for participation of such widely divergent structures as hippurates, penicillins, sulphonatcs, sulphonamides and organomercurial diuretics in what appears to be a single transport function. 522 The Effect of Diuresis and Diuretics upon the Renal Tubular Transport of Alkaline Earth Xl. \VALSER and J. R. TROUNCE Cations. (U.S.A.). Recent studies in this laboratory indicate that the major determinant of the renal clearances of Ca and Mg in the dog is the simultaneous clearance of Na. Salt-restricted animals excrete little Ca or Mg, even during mannitol diuresis. Infusion of saline leads to an mcreasc in the clearance of Ca (corrected for protein-binding) which is approximately equal to the change in Na clearance; big clearance increases even more. These studies have been extended to an examination of the effects of diuretic drugs. Dogs were infused with saline at 5 ml/min until urine flow exceeded 3 ml/min. Following several control periods, either chlormerodrin, 4 mg/kg; chlorothiazide, 10 mg/kg; or hydrochlorothiazidr, 5 mg, kg were injected intravenously. Chlormerodrin led to increases in Ca and Mg clearance even greater than the increases in Na clearance. The thiazidr derivatives decreased alkaline earth excretion although the natriuretic responses were comparable to those obtained with chlormerodrin. Changes in filtration rate or urine pH wrre minor and could not account for these results. The effect of ouabain was studied by injecting 50 ugjkg into one renal artery. Ca and Na clcaranccs rose in parallrl several fold, in the injected kidney but not in the contralateral kidney. Filtration rate either fell or remained constant. The drugs studied evidently exert profound and distinct effects upon the renal tubular transport of alkaline earth rations in addition to their known actions upon Na reabsorption.
523 Antidiuretic Responses to Neurohypophysial Hormones and Some of their Synthetic Analogues inDogsandRats. W. H. SAWYER, TV. T. &AX and H. B. VAN Dvne (U.S.A.‘I. The antidiuretic and vasopressor potencies of neurohypophysial peptides arc not necessarily proportional. The relative antidiuretic activity of a peptide may also depend on the species in which it is tested. By means of intravenous injection of
Abstracts
depolarized as well as in the polarized smooth muscle the presence of Ca is found to be essential for the initiation of contraction. The contractile responses of ACh and the r-rffcct of adrenaline show a \ cry similar Ca dependence. Thus, in the depolarized rat seminal vesicle, the isometric responses to ,2Ch and adrenaline dcclinc at the same rate when Ca is rrmoved from the bathing fluid and are restored at the same rate when Ca is reintroduced. Calcium itself inducrs a slow sustained contraction c;f the depolarized smooth musclc.~~’ However, ACh and adrenaline added on top of a Ca contraction produce a rapid further increase in tension, cvcn in a preparation maximally contracted to Ca. The contractile effect of Ca is strongly antagonized by the p-effect of adrenaline. In the depolarized rat uterus a substantial inhibition of the Cainduced contraction is produced by 10 O adrenaline and isoprenalinc. The experiments can be fitted into the hypothesis that Ca is a” early link in the initiation of muscular contraction. ACh and the a-effect of adrenaline, although obviously acting on different receptors since they are antagonized by dilrerent antagonists, may have a later reaction step in common, a mobilizing of intracellular Ca.
1. F,VANS, SCHII.D and THEXWF (19581, 3. P/ysiol., 143, 474. 2. EDMAN and SCMLD (1961), 3. PhyJiol, 155, 1OP.
517 Sodium Exchange in Smooth GO~DFORD (United Kingdom).
Muscle.
I’. .J.
It has been shown that a steady state was reached whrn pieces of guinea-pig taenia coli were set up in oxygenated Krebs’ solution at 35”C, and that the ?;a content, K content and inulin space of the smooth muscle became constant.“’ Nearly all the Na in the tissue exchanged with a half-life of 0.5 min when the bathing solution had been labelled with TaNa, and this exchange was too rapid to permit any resolution into intracellular and cxtraccllular components. Other pieces of taenia were equilibrated in a normal Ringer’s solution and then transferred to one in which all the Na salts had been replaced by Li; the Na again washed out of the tissue with a” initial half-life of 0.5 min but a portion remained in the muscle during the one hour immersion in the Li Ringer. As it was found@) that the Na content of the taenia approached that of the rxtrrnal bathing solution after equilibration of the muscle al 4’C. the experiment in Li solution was repeated at that temperature and the proportion of “nnexchangeable Na was then much greater. It is suggested that the Na which remained in the tissue in the presence of Li was intracclhtlar. The low content of bound Na at 35°C would then indicate a low intracellular concentration, which, . approachrd the concentration I” tne however,
of
Papers external solution at 4’C. This observation may tx used to interpret the normally very rapid Na cxchange, and to resolve its separate components.
1. GOODFORD,
3.
P. J.
and
HERHANSEN, K.
(1960‘.
Physiol., 153, 29P.
2. GOODFORD and NARROD.
Unpublished.
518 Action
of Cardiac Glycosides Muscle. T. GODFRAIND and
on a Smooth A.
GODFKAI.~I)
DE BECKER (Congo). A piece of guinea-pig ileum was used and bathed by a” oxygenated Tyrode solution. Contractions were recorded with a” isotonic frontal levw. Sweral cardiotonics have been studied (digitoxin. ouabain, k-strophanthoside, 5 x lo-* to 5 x 10 3 v/w). All cause a contraction of the muscle: relaxation appears in the same solution. There is no relation between the dose and the height of contraction. This is a tachyphylactic action. The action of these drugs on cholinergic OLhistaminrrgic muscle stimulation appears to lx biphasic. First we observed a potentiation of the effects of acetylcholine and histamine. This potcntiation occurs simultaneollsly with the contractile responsr of the ileum to the glycoside and appear\ only whrn contraction is produced by chemical transmitters. When the intestine is stimulatrcl coaxially, the phcnornenon still appears but in the prcsencc- of atropine, no potentiation is evoked. This first phase is followed by a competitive inhibition of the effects of agonists. Several factors are concerned with this inhibitory action: the concentration of glycoside in the bath, the time of contact before contraction and the contractile activity of the muscle itself. Graphical representation of thest factors give a typical saturation curve. There is an obvious parallelism between these data and the influence of the same factors on ion exchanges. Another point of similarity is the action of desoqcorticosterone. This drug which depresses the elrcct\ of glycosides on ion movements, reduces also thcilaction against and competitive acctylcholim histamine. 519 Effect
of Hydrochlorothiazide on Renal Electrolyte Gradient in Glucose Diuresis and Diabetes Insipidus. J. I’. BAER, .A. 1.. BROOKS and K. M. NOLL (U.S..%.).
In edematous patients. hydrochlorothiazide produces saluresis and estcnsive water diuresis. In diabetes insipid&, on the other hand, thiazide\ actually dilninish urine flow \vhile rendering the urine more hypertonic. The present experiments were designed to relate these actions of hydrorhlorothia&e to the magnitude of the clwtrolyte gradient in the kidney. Hyclrorhlorothiazidc ( IOO mg/kg/I.V.) did not affect the rrnal elertrolvte aradient in uninfusetl Y
Abstracts of Papers dogs. The infusion of 5 per cent glucose at to ml/ min alone obliterated the renal electrolyte gradient that is present in normal uninfused dogs. Hy-drochlorothiaLide did not restore the gradient in the glucose-infused dogs. In rats vith experimental diabetes, a marked gradient occurred, the sodium content increasing from ;o mcq/kg \vct wt. in the cortex to :joo meq/kg \vet \vt. in the papilla. Administration of hvdrochlorothiazide for 3 days (45 mg/kg orally in di;-ided doses) decreased urine tlow and \vatcr intake promptly : electrolyte excretion decreased more slowly. The sodium gradient was minimally atIectec1 by the llydrochtorothiazide treatment.
520 The Role of Hyaluronidase Antidiuretic Hormone. (U.S.S.R.).
in the Action of A. G. GINETZINSKY
In the state of dehydration the urine of all tcrrestrial vertebrates contains hyaluronidase. Enzymatic activity of the urine drops to the zero level after water loading when thr secretion of XDH i5 inhibited. \Vhcn suitable experimental conditions excluding electrolyte and dilution effect are created the correlation between hyaluronidase activity of the urine and the extent of diuresis is maintained. Hyaluronidase inhibitors when administrated directly into the renal artery increase dim&. This effect appears on the side of the injection only. If the structures producing antidiuretic hormone are destroyed hyaluronidase disappears from the urine, but after pitressin injection the urine reacquires fcrmmtative activity. Ily means of the stop flow method, it was found that hyaluronidase appears in the urine produced by the distal parts of the nephron. Proximal urine enzyme. Cytological and histocontains no chemical investigations showed that rcnal rpithelium acted upon by ADH secretes a substance containing protein. The intercellular cement and the basement membrane of the collecting ducts and of the distal parts of the nephron contain hyaluronic acid. The XDH by means of hyaluronidase effect is produced liberation. The enzyme depolymerizes hyaluronic acid which makes the tubule wall waterproof. its permeability increases. The Accordingly, osmotic free water then is reabsorbed and antidiurrsis occurs. 521 Renal Transport ing Hypothesis.
of Organic Anions: A UnifyA. DESPOPOULOS (U.S.A.).
;\ctive renal tubular excretion of organic anions has been examined in an attempt to define the nature of the physico-chemical interaction between transported substrates and a postulated receptor in Comparison of more than 150 organic renal cells. anions permits tentative description of a general molecular structure which defines substrate specificity of the transport system. Intramolecular
157
components which appear to be essential for transport include an unsaturated oxygen group (-C:O; --S:O) and an ionic function (-COOH: -SO,OH: -SO,NH-). A three-point interaction with the receptor can be satified by formation of a hydrogen bond at the unsaturated oxygen (-C :O : -S :0) and both a hydrogen bond and an ionic bond at the anionic group. These postulates are invoked to account for participation of such widely divergent structures as hippurates, penicillins, sulphonatcs, sulphonamides and organomercurial diuretics in what appears to be a single transport function. 522 The Effect of Diuresis and Diuretics upon the Renal Tubular Transport of Alkaline Earth Xl. \VALSER and J. R. TROUNCE Cations. (U.S.A.). Recent studies in this laboratory indicate that the major determinant of the renal clearances of Ca and Mg in the dog is the simultaneous clearance of Na. Salt-restricted animals excrete little Ca or Mg, even during mannitol diuresis. Infusion of saline leads to an mcreasc in the clearance of Ca (corrected for protein-binding) which is approximately equal to the change in Na clearance; big clearance increases even more. These studies have been extended to an examination of the effects of diuretic drugs. Dogs were infused with saline at 5 ml/min until urine flow exceeded 3 ml/min. Following several control periods, either chlormerodrin, 4 mg/kg; chlorothiazide, 10 mg/kg; or hydrochlorothiazidr, 5 mg, kg were injected intravenously. Chlormerodrin led to increases in Ca and Mg clearance even greater than the increases in Na clearance. The thiazidr derivatives decreased alkaline earth excretion although the natriuretic responses were comparable to those obtained with chlormerodrin. Changes in filtration rate or urine pH wrre minor and could not account for these results. The effect of ouabain was studied by injecting 50 ugjkg into one renal artery. Ca and Na clcaranccs rose in parallrl several fold, in the injected kidney but not in the contralateral kidney. Filtration rate either fell or remained constant. The drugs studied evidently exert profound and distinct effects upon the renal tubular transport of alkaline earth rations in addition to their known actions upon Na reabsorption.
523 Antidiuretic Responses to Neurohypophysial Hormones and Some of their Synthetic Analogues inDogsandRats. W. H. SAWYER, TV. T. &AX and H. B. VAN Dvne (U.S.A.‘I. The antidiuretic and vasopressor potencies of neurohypophysial peptides arc not necessarily proportional. The relative antidiuretic activity of a peptide may also depend on the species in which it is tested. By means of intravenous injection of