s175
1615
PHRENIC PRBPARATIONOFNBONATALRAT.
SEROTONIN-INDUCED
BURST RHYTHM IN RIB-ATIACHBD YOSHIMINAKAZONO*.MAMORU
SPINAL CORD
AOKI. DemofPhvsiol., Sannoro Med. Univ. Sch. of Med.. Sapnoro 060: *Fat. of Sci. & Enein.. Aovama Gakuin Univ.. Tokvo 157. Japan
To investigate the genesis of respiratory neural rhythm in the mammalian spinal cord, we experimentally induced the spinal respiratory rhythm in rib-attached spinal cord preparations (decerebrated at the upper cervical level) isolated from neonatal rats (0 - 3 days). Phrenic burst discharges were recorded unilaterally from a phrenic nerve by a suction electrode. Serotonin (54-R, 50 w) was bath-applied for 5 min into the recording chamber with a perfusate (modified Krebs’, 25 - 27 ‘C). From 1 to 2 minutes after the 5-HT application, tetanic contraction of the rib cage occurred and then followed by rhythmic contraction-relaxations of flexors of neck and the rib cage with a period of 10 - 30 s. Concomitantly with the muscle contraction-relaxation cycles, the phrenic bursts were recorded with a duration of 5 - 10 s. These bursts synchronized with the contraction rhythm locked to the relaxation phase. These results clearly demonstrate that the spinal cord has an ability for generating respiratory rhythm.
INFLUENCES OF VAGAL AFFERENT INPUTS ON RESPIRATORY RHYTHM DURING INDUCED VOCAXZATION. JWN -A. KFJSUKE ,%I=. KOH YOSHIDA. ISAMU SATOH,
1616 YOSHIO
NAKAJIMA.
Electrical
Dem.of
stimulation part
Physiol.,Chiba
(duration,
Univ.Sch.of
0.2 ms;
Med.,Chiba
260,Japan
frequency,
100 Hz; lasting for 10 6) of gray (PXI induces vocalization, repeats inspiration and expiration. To elucidate the role of vagal afferent inputs in controlling vocalization, we investigated the effects of 1) vagotmy and 2) paralyzation (with gallamine triethiodide) on respiratory rhythm during electrically-induced vocalization. Experiments were performed on ketamine the caudal lateral which alternately
anesthetized
of the periaqueductal
cats.
1) After
bilateral vagotw at cervical level, PAG stimulation could not induce vocalization; inspiration was not switched to expiration. 2) After paralyzation, PAL3 stimulation induced only apneusis. Lung inflation, caused by pressure application to the lung during PAG stimulation, switched respiratory phase from inspiration to expiration. In contrast, luug deflation, caused by pressure termination, switched respiratory phase from expiration to inspiration. These results suggest that the vagal afferent input, i.e. HeringBreuer reflex, is essential for respiratory rhythm during PA&induced vocalization.
1617
SYNAPTIC
ORGANIZATION
OF AFFERENTS
SOLITARII TO THE ESOPHAGEAL TETSU HAYAKAWA. JUN 01 ZHENG, KATUYA HVOUO Colleae
of
Medicine.
Nishinomiya,
FROM
MOTONEURONS ZYO,
DeDartment Hvocro 663,
THE
IN
TRACTUS THE NUCLEUS AMBIGUUS. NUCLEUS
of Anatomv, Japan
Neurons of the nucleus tractus solitarii (NT.?) serve as interneurons in swallowing and peristalsis. We investigated whether NTS project directly to the esophageal neurons in the compact formation of the nucleus ambiguus (AmC), and ultrastructure of their terminals. Following WGA-HRP injection into NTS of the rat, many anterogradely labeled terminals were found in the neuropil of AmC. Most labeled terminais were Gray's type I, but a few were Gray's type II. Less than 20% of axosomatic Lerminals in the esophageal neurons were anterogradely labeled. There were also retrogradely labeled small neurons, which received many anterogradely labeled axosomatic terminals (more than 30%). All those axosomatic terminals were Gray's type I. Thus, reciprocal connections were recognized between small neurons and NTS.