Effect of the H2-receptor antagonist metiamide on carbachol- and histamine-induced gastric acid secretion in the Atlantic cod,Gadus morhua.

Gastric acid secretion was measured in swimming codfish surgically equipped with a catheter draining the stomach. Intramuscular injection of histamine (15.6 mug/kg-h) or carbachol (5 mug/kg-h) stimulated the secretion of acid, carbachol in addition caused a marked decrease in drinking rate of the fishes. Administration of 10 mumol/kg-h metiamide completely prevented the acid secretion induced by both drugs. The carbachol effect on the drinking rate, interpreted to mirror contraction of the stomach following stimulation of muscarinic receptors, was not affected by metiamide.