1. The Effect Of Motilin On Vagal Afferent Nerve 2. The Role Of Azithromycin On Intragastric Pressure And Gastric Electrical Activity

Objectives: To investigate the effect of motilin on spontaneous afferent nerve discharge and gastric distention-induced afferent nerve discharge and explore the corresponding mechanism.Methords: Experiments were performed in anesthetized SD rats. The sensory impulses of subdiaphragmatic vagal nerve were recorded by the RECORDER. Different dosages of motilin were intravenous injection. Some rats were pretreated with ondansetron or atropine, and then injected high-dose motilin.Results: Intravenous low dose (1μg/kg) had no effect, intravenous medium dose and high dose (5μg/kg and 40μg/kg respectively) caused obvious increase of spontaneous afferent discharge and gastric distention-induced afferent discharge. Pretreatment with ondansetron almost completely blocked the effects of motilin. Atropine had no obvious influence with the effect of high-dose motilin. Ondansetron inhibited afferent nerve discharge by itself,and atropine also did, but the latter failed to reach statistical significance.Conclusion: Motilin can excite spontaneous afferent nerve discharge and gastric distention-induced afferent nerve discharge. Vagal afferent nerve may play roles in the actions of motilin, 5-HT receptor are probably involved in the effect, but not atropine . Objective: To observe the effect of azithromycin on intragastric pressure(IGP) and gastric electrical slow wave, and explore the dependent nerve and receptor.Methords: Experiments were performed in anesthetized SD rats. Animals received intravenous injection of different doses azithromycin or normal saline(1 ml), both IGP and gastric electrical activity were recorded by BL-410 Biological signal recording system(n=30). Pretreatment of atropine was intraperitoneal injection, and then injected high-dose azithromycin and recorded IGP(n=6). Pretreatment of vagotomy was carried out, and then used normal saline or high-dose and recorded IGP and gastric electrical activity(n=12).Results: Intravenous medium dose azithromycin(75mg/kg) and high dose azithromycin(150mg/kg) caused the increase of IGP, Different doses had no obvious influence on gastric electrical slow wave amplitude and frequency. No obvious changes in both IGP and gastric electrical activity was observed in normal saline. Atropine almost completely blocked the effect of azithromycin on IGP. Pretreatment of subdiaphragmal vagotomy turned the increase of IGP induced by azithromycin, IGP discreased obviously ,but gastric electrical activity were not changed.Conclusion: Intravenous azithromycin could make IGP increase, this effect might rely on vagus and cholinergic receptor; Azithromycin might have no obvious effect on gastric electrical slow wave amplitude and frequency.