title: Actions of Ca2+ antagonists on the guinea-pig ileal myenteric plexus preparation.
abstract: The guinea-pig ileal myenteric plexus preparation has been used to compare the actions of three Ca2+ channel antagonists, D 600 (methoxyverapamil), nicardipine and diltiazem, on smooth muscle contractions and acetylcholine release in response to electrical stimulation. Acetylcholine release was not affected by these agents at concentrations of 10(-6)-10(-5)M. In confirmation of previous work, however, the smooth muscle contractile responses were effectively inhibited at these concentrations. Quercetin, a non-Ca2+ channel antagonist, was approximately equieffective in blocking both acetylcholine release and smooth muscle contractions. These data suggest that differences may exist in the antagonist sensitivity of voltage-dependent Ca2+ channels.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D006636:Histamine Release / Q000187:drug effects; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009197:Myenteric Plexus / Q000187:drug effects*
chemical_list: D002121:Calcium Channel Blockers; D002118:Calcium