The effect of atropine on acid secretion stimulated by acetylcholine, histamine and gastrin in the isolated whole stomach of the rat.

1 An isolated stomach preparation from immature rats has been used to study the effect of atropine on gastric acid secretion. 2 The acid secretory response to acetylcholine was not inhibited by atropine at a concentration of 0.3 micrometer. Concentrations of atropine of 1 to 3 micrometer produced a measurable inhibition of acid secretion, and a concentration of atropine of 10 micrometer caused a complete block of acid secretion which could not be surmounted by high concentrations of acetylcholine. 3 The acid secretory response to histamine was not inhibited by concentrations of atropine of up to 1 mM. 4 Concentrations of atropine of 1 micrometer and 10 micrometer did not inhibit gastrin-stimulated acid secretion, although a significant inhibition of acid output was observed with atropine at concentrations of 0.1 mM and 1 mM. 5 These findings are discussed in relation to the role of cholinergic mechanisms in the control of gastric acid secretion.