COMPARATIVE-ANALYSIS OF THE VAGAL-STIMULATION OF GASTRIC-ACID SECRETION IN RODENT ISOLATED STOMACH PREPARATIONS

1 Electrical field stimulation produced a tetrodotoxin-sensitive, frequency-dependent, release of acid from isolated, lumen-perfused, stomach preparations from mouse, immature rat and guinea-pig. 2 In the guinea-pig and mouse preparations, the frequency-dependent response was abolished by hexamethonium, acetylcholine (ACh) muscarinic (M) and histamine H-2-receptor blockade, consistent with the hypothesis that the vagal ACh acts indirectly by stimulating the release of endogenous histamine. 3 In contrast, in the rat preparation the frequency-dependent response was partially refractory to all of these inhibitors. However, a combination of H-2- and ACh M-receptor blockade did abolish the effect. 4 We conclude that vagal-stimulated acid secretion in the rat, unlike the other two species, behaves as though there is a direct innervation of the oxyntic cells by either cholinergic or noncholinergic neurones.