Yamamoto O, Matsunaga Y, Haga N, Mizumoto A, Itoh Z
Gastrointestinal Research Laboratories, Gunma University, Maebashi, Japan.
Gastroenterology. 1994 Jun;106(6):1533-41. doi: 10.1016/0016-5085(94)90407-3.
BACKGROUND/AIMS: Intragastric acidification at pH 1.0 strongly inhibits phase III contractions in the dog, but this mechanism is not well known. We studied the mechanism in conscious dogs.
Vagally denervated and innervated gastric pouch dogs were prepared. Force transducers were chronically implanted on the serosa of the pouch, main stomach, and mid-duodenum. The pH of the perfusate was monitored.
Administration of histamine (40 micrograms.kg-1.h-1 intravenously [i.v.]) and instillation of acidic saline at pH 1.0, but not pH 2.0, into the main stomach strongly inhibited the motilin-induced (0.1 microgram/kg i.v.) phase III activity in the main stomach and the innervated pouch but did not influence contractions in the extrinsically denervated pouch. Famotidine completely reversed the histamine-induced inhibition of phase III in the main stomach and Pavlov pouch. Acidification of the pouch itself or duodenum at pH 1.0 did not affect contractions in the main stomach and pouch of either type.
The mechanism of inhibition of motilin-induced phase III activity by acid in the stomach involves the intact vagovagal reflex, but sympathetic participation is not completely ruled out. The inhibition of motilin-induced phase III activity may originate in the antral mucosa of the stomach.
背景/目的：胃内pH值为1.0时的酸化作用可强烈抑制犬的Ⅲ期收缩，但该机制尚不清楚。我们在清醒犬中研究了此机制。
制备了迷走神经切断和未切断的胃小囊犬。将力传感器长期植入小囊、主胃和十二指肠中部的浆膜上。监测灌注液的pH值。
静脉注射组胺（40微克·千克⁻¹·小时⁻¹）并向主胃内滴注pH值为1.0而非pH值为2.0的酸性盐水，可强烈抑制胃动素诱导（静脉注射0.1微克/千克）的主胃和有迷走神经支配的小囊的Ⅲ期活动，但不影响去迷走神经支配的小囊的收缩。法莫替丁完全逆转了组胺诱导的主胃和巴甫洛夫小囊Ⅲ期的抑制作用。小囊本身或十二指肠pH值为1.0时的酸化并不影响两种类型的主胃和小囊的收缩。
胃内酸抑制胃动素诱导的Ⅲ期活动的机制涉及完整的迷走-迷走反射，但不能完全排除交感神经的参与。胃动素诱导的Ⅲ期活动的抑制可能起源于胃的胃窦黏膜。
