Inhibitory effect of etintidine (BL-5641), a new type of H2 receptor antagonist, on binding of [3H]-cimetidine to plasma membrane and histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands.

A comparative study was carried out between the inhibitory effects of cimetidine and those of etintidine (BL-5641), a new type of H2 receptor antagonist, on the binding of [3H]-cimetidine to plasma membranes as well as on histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands. Both cimetidine and etintidine inhibited the binding of [3H]-cimetidine to plasma membranes, in a dosedependent manner, with an IC50 of 1.70 × 10-6 M and 0.51 × 10-6 M, respectively. The two drugs also inhibited histamine-stimulated cellular cAMP production in a dose-dependent manner, shifting the histamine dose-dependent curve of cellular cAMP production to the right. The PA2 calculated from the result obtained was 6.41 for cimetidine and 6.82 for etintidine.