Cyclic nucleotides and the regulation of canine gastric acid secretion

Abstract

The response of the cyclic nucleotide system (cAMP, cGMP, adenylate cyclase, guanylate cyclase, and specific phosphodiesterases) to two gastric acid secretagogues, histamine and acetylcholine, and two secretory inhibitors, prostaglandin E₂ and secretin, was studiedin vivo andin vitro in canine gastric fundic mucosa. Histamine and acetylcholinein vivo failed to stimulate cAMP but significantly increased cGMP;in vitro they affected neither adenylate cyclase nor guanylate cyclase. Prostaglandin E₂ and secretin, however, increased cAMPin vivo and significantly stimulated adenylate cyclasein vitro. Specific phosphodiesterases were unaffected by these compounds. The changes, while not specifically localized to the acid-producing cells, are consistent with the suggestion that the control of canine gastric acid secretion may be mediated by changes in mucosal cAMP and cGMP.