The effect of different calcium antagonists on histamine- and carbachol-induced acid secretion in the isolated mouse stomach.

Earlier experiments suggested that the action of muscarinic agonists in gastric acid secretion might be partly mediated by endogenous histamine release. This possibility could be tested by use of various calcium antagonists provided that they show different activity on histamine- and carbachol-induced secretion. In the present work, three calcium antagonists, verapamil, nifedipine and sodium nitroprusside were used on the isolated mouse stomach where acid secretion induced by histamine and by carbachol was measured. Verapamil (100 microM) did not affect either histamine- or carbachol-induced acid secretion. Nifedipine (100 microM) reduced histamine-induced acid secretion, whereas the effect of carbachol remained unchanged. Sodium nitroprusside (10-100 microM) reduced both histamine- and carbachol-induced acid secretion. The differences in action of calcium antagonists in histamine- and carbachol-induced acid secretion could exclude the possibility that the effect of carbachol is partly mediated by histamine release from mast cells present in the mouse stomach.