Histamine interaction on surface recognition sites of H2-type in parietal and non-parietal cells isolated from the guinea pig stomach

In gastric cells isolated by pronase digestion from the guinea pig, histamine stimulated cAMP production in 3 fundic cell fractions (EC50 = 1.6--2 x 10(-4) M) enriched in parietal (94%), peptic (63%) and mucous cells (87%) as well as in antral cells (EC50 = 4 x 10(-4) M) that are devoid of parietal cells. Histamine stimulations were completely inhibited by the H2 antagonist cimetidine (Ki = 0.27--0.57 x 10(-6) M) or by the H1 antagonist diphenhydramine, but at 100-times lower potency (Ki = 22--45.7 x 10(-6) M), indicating the presence of histamine H2 receptors in parietal and nonparietal cells of the guinea pig gastric mucosa.