The change of motility compared with the gastric-acid secretion after atropine administration in rats

The vagal nerve has important role in the regulation of gastric acid secretion and motility. It was not known how the parts of gastric function are influenced by the effects of cholinergic innervation. Early study proved that the ED50 value in inhibition of gastric acid secretion of atropine is 1.78µmol/kg (-log: 5.75)(Mózsik and Jávor. Dig. Dis. Sci. 1988;33:92–105).

The aims of study were to determinate the ED50 value of atropine in relation the decrease of gastric emptying and to compare the both ED50 levels.

Materials and methods: The observation was carried out on Sprague-Dawley rats weighing 210–230g of body weight. The animals were fasted for 24h before the experiments but water was given freely. The test solution contained 1.5% of methylcellulose dispergated in water painted with 0.05% phenol-red. The rats were given 1.5ml of test solution intragastrically. Atropine was given i.p. in 0.001 (1.48 nmol)-0.005–0.01–0.05–0.1–0.5–1.0 (1.48µmol) mg/kg doses at 30min before the test solution administration. The rats were killed at 20min after methylcellulose application, when the phenol-red content was measured spectrophotometrically in the stomach. The stomach emptying was calculated in percent values.

Result: After the determination of dose-dependent decrease of gastric emptying the ED50 value derived 0.108µmol/kg (-log: 6.97).

Conclusion: The effect of atropine is ten times higher on the gastric motility than on the acid secretion in rats.

The study was supported by grants of National Research Found (OTKA), Hungary (No. F037639, No. F042912).