PT  - JOURNAL ARTICLE
AU  - A. M. CHERET
AU  - F. PIGNAL
AU  - M. J.-M. LEWIN
TI  - Effects of H<sub>2</sub>-Receptor Antagonists Cimetidine, Ranitidine, and ICI 125,211 on Histamine-Stimulated Adenylate Cyclase Activity in Guinea Pig Gastric Mucosa
DP  - 1981 Sep 01
TA  - Molecular Pharmacology
PG  - 326--330
VI  - 20
IP  - 2
4099  - http://molpharm.aspetjournals.org/content/20/2/326.short
4100  - http://molpharm.aspetjournals.org/content/20/2/326.full
SO  - Mol Pharmacol1981 Sep 01; 20
AB  - 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.