ANALYSIS OF ANOMALOUS pKB VALUES FOR METIAMIDE AND ATROPINE IN THE ISOLATED STOMACH OF THE MOUSE

Abstract

In the isolated, lumen‐perfused, stomach preparation of the mouse, metiamide was found by kinetic analysis to behave like a simple competitive antagonist of histamine‐stimulated acid secretion. However, the pKB estimate of 5.08 was significantly lower than that found in guinea‐pig atrium (6.0) or rat uterus (6.1) suggesting that H2‐receptors might not be homogeneous. A similar analysis showed that atropine also behaved like a simple competitive antagonist of bethanechol‐stimulated acid secretion and the estimated pKB (7.65) was significantly lower than the standard estimate of this parameter in guinea‐pig ileum (9.0). Either the muscarinic cholinoceptors in mouse stomach were also anomalous ..