Influence of atropine, metiamide and vagotomy on cAMP of resting and stimulated gastric mucosa.

In normal rats the effect of atropine and metiamide was studied on cAMP levels of resting and histamine-, pentagastrin-, carbachol- and insulin-stimulated gastric mucosa. In vagotomized rats gastric mucosal cAMP levels were investigated under basal conditions and after insulin. Atropine and metiamide did not alter cAMP levels of resting gastric mucosa. Truncal vagotomy caused an increase in gastric mucosal cAMP, which was not affected by insulin. All gastric secretagogues caused a significant rise in gastric mucosal cAMP levels, which was not antagonized by atropine. Metiamide effectively blocked the rise in cAMP concentration after histamine and pentagastrin, but not that evoked by cholinergic stimulation. The results are consistent with the view that the in vivo rise of gastric mucosal cAMP after carbachol or insulin is not due to a direct cholinergic action. From the spectrum of inhibitory actions of metiamide it looks as if the increase in rat gastric mucosal cAMP concentration after histamine and pentagastrin administration is mediated by H2-receptor stimulation.