The direct excitatory effects of cimetidine on the smooth muscle of guinea pig ileum.
1. Cimetidine produced dose-dependent contractions in isolated guinea pig ileum and these responses were not blocked by mepyramine the H1-receptor antagonist. 2. Atropine competitively inhibited the cimetidine-induced contractions in the guinea pig ileum. 3. Cimetidine-induced responses were potentiated in the presence of eserine. Magnesium ions non-competitively inhibited the contractions due to cimetidine. Our findings suggest that cimetidine excites the guinea pig ileum through muscarinic receptors by releasing acetylcholine.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology*; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010830:Physostigmine / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects
D006146:Guanidines; D011976:Receptors, Muscarinic; D001285:Atropine; D002927:Cimetidine; D010830:Physostigmine; D011738:Pyrilamine; D008274:Magnesium; D000109:Acetylcholine