[Regulatory role of 5-hydroxytryptamine and motilin in migrating motor complex of small bowel in dogs].
Migrating motor complex (MMC) was recorded by chronically implanted strain gauge transducers on the serosa of small bowel in conscious dogs. Two silastic catheters for injecting drugs and taking blood samples were put respectively in a vena jugularis externa and in a jejunal artery which perfused a 10-15 cm intestinal segment. The present study was undertaken to observe the effect of drugs administered intravenously and intraarterially on MMC and alterations of plasma 5-hydroxytryptamine (5-HT) and motilin in different phases of MMC. The results showed: (1) Levels of plasma 5-HT and motilin showed cyclical fluctuations in different phases of MMC, and 5-HT reached peak before peak of motilin. Plasma 5-HT level reached a peak [(41.2 +/- 1.3) ng/ml] in the later period of phase II, which increased significantly as compared with phase I [(22.4 +/- 1.1) ng/ml] (P < 0.01), but plasma motilin level had a peak [(580.0 +/- 30.2) pg/ml] in phase III of MMC, which was higher than that in phase I [(140.0 +/- 21.0) pg/ml] (P < 0.01). (2) Intravenous motilin and intraarterial 5-HT and motilin could induce phase III contraction in the canine proximal small bowel and in the perfused segment respectively. Amplitude of contractions caused by motilin was higher than that by 5-HT in the perfused segment. (3) 5-HT receptor antagonist, motilin antiserum, 5,6-dihydroxytryptamine and tetrodotoxin perfused intra-arterially inhibited expression of MMC in the perfused segment and its caudal propagation. We conclude that plasma 5-HT and motilin may be dominant factors which initiate MMC of canine small bowel, and 5-HT peak appears before peak of motilin. 5-HT neurons and motilin neurons in enteric nervous system may play an important role in controlling MMC of canine small bowel.
Yang
C M
CM
Department of Physiology, Institute of Basic Medical Sciences, CAMS and School of Basic Medicine, PUMC, Beijing 100005.
Zhou
L
L
Zhang
H
H
Hao
W
W
D000818:Animals; D004285:Dogs; D005260:Female; D007583:Jejunum / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009037:Motilin / Q000378:metabolism / Q000494:pharmacology*; D016065:Myoelectric Complex, Migrating / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*
D012701:Serotonin; D009037:Motilin