Abstract
Histamine stimulation of adenylate cyclase activity in broken cells isolated from guinea pig gastric mucosa was competitively inhibited by the thiazole derivative ICI 125,211 and the furane derivative ranitidine, with pA2 of 7.62 (Ki = 2.39 x 10-8 M) and pA2 of 6.90 (Ki = 1.25 x 10-7 M), respectively, i.e., potencies 19 times and 4 times superior to that of the classical H2-receptor antagonist cimetidine (pA2 = 6.34; Ki = 4.57 x 10-7 M). These results are consistent with the reported pharmacological potencies of the antagonists on guinea pig right atrium and on gastric acid secretion in vivo. Thus, the requirement of an imidazole ring in the structure of H2-receptor antagonists can be definitely ruled out.
- Copyright © 1981 by The American Society for Pharmacology and Experimental Therapeutics
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