Stimulatory effect of forskolin on gastric acid secretion in the rat, in vitro and in vivo.

The effect of forskolin, a potent adenylate cyclase activator, was studied on rat gastric acid secretion in vitro and in vivo. In the isolated gastric mucosa, forskolin was 25 and 100 times more potent than histamine and dibutyryl cyclic AMP respectively, with an EC50 of 2 microM and a maximum effect at 8-10 microM. In the lumen-perfused anaesthetised rat, acid secretion in response to a series of bolus i.v. injections of forskolin failed to show dose dependency, despite dose-related hypotensive effects. Secretory responses to i.v. infusions of forskolin were dose-related and were associated with a rise in gastric mucosal blood flow despite marked hypotension. These results indicate that forskolin has a direct secretagogue effect on parietal cells which, under some circumstances may be modified by its other pharmacological actions.