Inhibitory effect of misoprostol on gastric acid secretion in vitro. Qualitative differences from natural prostaglandins

The synthetic PGE1 analog, misoprostol, was shown to have a marked inhibitory effect on gastric secretion as determined in the isolated gastric fundus from immature rats. It inhibited both the unstimulated and pentagastrin-stimulated acid secretion at 10(-7)-10(-4) molar concentrations. Its effect was different from that of PGE1 and PGE2, which did not affect basal acid secretion (up to 3 x 10(-5) M), although they inhibited to the same extent as misoprostol the pentagastrin-induced acid secretion. When given by "mucosal" application, misoprostol (10(-7)-10(-5) M) behaved similar to the mast cell stabilizer, compound FPL 52694, but its maximum reduction response was only 50%. The above data suggest that misoprostol has additional antisecretory mechanisms of action not shared by the classical natural prostaglandins.