Acid secretion by guinea‐pig isolated stomach.

Abstract

Both histamine acid phosphate (1-4 .mu.g/ml) and theophylline hydrate (0.2-3.2 mg/ml) separately stimulated HCl secretion from the guinea-pig stomach preparation. A linear dose-response relationship was obtained for theophylline. Addition of theophylline (0.2 and 1.6 mg/ml) during maximal response to histamine increased the secretion further; addition of histamine during maximal response to theophylline did not cause further secretion. The secretory activities of 5-methyl histamine [N.alpha.-MeH] (0.3-5.0 .mu.M), N-.alpha.-diurethyl histamine [N.alpha.-Me2H] (1.2-9.5 .mu.M) and 5-MeH (1.5-12 .mu.M) were compared with histamine (0.9-13 .mu.M) on a threshold background secretion induced by theophylline (0.2 mg/ml). Linear log-dose response relationships were obtained for each test drug. N.alpha.-MeH is a more potent secretagogue than histamine. Pentagastrin (0.3-1.0 .mu.g/ml) stimulated HCl secretion in approximately half the experiments. The response was often transitory. Pentagastrin had no effect on HCl secretion although subsequent administration of histamine did stimulate HCl secretion.