| The article is composed of two parts. The first part is comparative research of the effects of three anesthetics on contractility of isolated gastroduodenal smooth muscle in rats. The three anesthetics were urethane, pentobarbital sodium and chloral hydrate, respectively. The normal Tyrode's solution for isolated gastroduodenal smooth muscle was changed into another Tyrode's solution which contained one of the three anesthetics. And we designed three concentrations for each anesthetic, which were 1/3 standard concentration, 1/2 standard concentration and standard concentration. The standard concentration was the concentration that anesthetic distributed in the extracellular fluid in vivo. And a two channels reconder was used to record the contraction waves of isolated gastroduodenal smooth muscle.The results showed that the three anesthetics all inhibited contractibiligy of isolated gastroduodenal smooth muscle. In terms of standard concentration, urethane had the largest effect on motility index of isolated gastric smooth muscle, and the inhibitory rate was 95.6% (p < 0.01), however, chloral hydrate had the least inhibitory effect on that, and the inhibitory rate was 56.4% (P > 0.05). To the motility index of isolated duodenal smooth muscle, chloral hydrate had the largest effect on it and the inhibitory rate was 99.5% (p < 0.01), however, pentobarbital sodium had the least effect on it, and the inhibitory rate was 48.9% (P > 0.05). According to the results of our experiments, we suggest that in the experiments about effects of central nervous system on duodenal motility in rats, pentobarbital sodium should be the most appropriate anesthetic. However, in the experiments about effects of central nervous system on gastric motility in rats, chloral hydrate should be the most appropriate anesthetic.The second part is about the effects of electrical stimulation of nucleus ambiguous (NA) on gastric motility and mucous secretion in rats. The animals were divided into two groups.In the first group, the right or left NA was stimulated under four stimulative parameter, which were 30Hz, 0.15mA; 30Hz, 0.20mA; 40Hz, 0.15mA and 40Hz, 0.20mA, respectively. And the electrical stimulations all were durative single stimulation and the width of stimulation was 0.30ms. The results showed that electrical stimulation of NA significantly inhibited gastric motility and the right NA had greater inhibitory effects on gastric motility than the left NA.In the second group, the diaphragmatic vagus nevers were cut, and the gastric motility after stimulation was compared with the gastric motility before stimulation. The results showed that the inhibitory effects of NA on gastric motility were withdrawn by diaphragmatic vagotomy. Furthermore, the amplitude of gastric motility significantly increased.Conclusion: NA inhibits gastric motility and the inhibitory degree of right NA is more than that of left NA, and the inhibitory effect is mediated by vagus. However, NA has no effects on gastric mucous secretion.
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