Estimation of pKB values for histamine H2-receptor antagonists using an in vitro acid secretion assay.
1 Histamine H2-receptor antagonism by burimamide, metiamide and cimetidine was analysed under apparent equilibrium conditions in the lumen-perfused isolated stomach preparation of the mouse. 2 The behaviour of these compounds was not incompatible with simple competitive antagonism but the estimated pKB values (-log KB) were all significantly lower, by about 1 log unit, than reference values reported for guinea-pig atrium or rat uterus. 3 There seems no need to propose that the parietal cell receptors are somehow different from the others; metiamide continually appears in the gastric juice so that a steady-state but not equilibrium can presumably be reached with respect to the bath concentration and this could keep the antagonist concentration artificially low in the region of the receptors.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D008785:Metiamide / Q000378:metabolism; D051379:Mice; D011970:Receptors, Histamine H2 / Q000187:drug effects / Q000378:metabolism
D006635:Histamine H2 Antagonists; D011970:Receptors, Histamine H2; D008785:Metiamide