Metiamide: more than an H2-receptor antagonist.

The effect of metiamide on acid secretion and calcium uptake by the frog gastric mucosa was tested alone and in combination with histamine, pentagastrin, aminophylline, and dibutyrl cyclic AMP (db cAMP). Metiamide inhibited all stimulants including db cAMP which presumably acts intracellularly beyond the H2 receptor. Metiamide, therefore, actively inhibits at a point within the cell beyond the adenylated cyclase membrane receptor complexes. Metiamide also increases calcium influx into the parietal cell, suggesting yet another possible mechanism of inhibition.