title: Action of mefloquine on toad isolated rectus abdominis muscle.
abstract: The effects of mefloquine and quinine on acetylcholine-induced contractures of the toad rectus abdominis muscle have been investigated. Both drugs depressed acetylcholine-induced contractures in a dose-related and non-competitive manner. A partial reversal of the block was observed in the presence of 4-aminopyridine (10, 50 microM) and increased Ca2+ content (1.25x) of the Ringer solution. In both cases, the mefloquine-induced blockade was more readily reversed than that induced by quinine. Mefloquine and quinine at concentrations greater than 100 and 500 microM, respectively, also elicited a direct contractile response on the muscle. Quantitative differences in their contractile activity have been attributed to the greater lipid solubility and tissue binding affinity of mefloquine.
mesh_terms: D015761:4-Aminopyridine; D000109:Acetylcholine / Q000494:pharmacology; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002025:Bufonidae; D002118:Calcium / Q000494:pharmacology; D066298:In Vitro Techniques; D015767:Mefloquine; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011804:Quinolines / Q000494:pharmacology*
chemical_list: D000631:Aminopyridines; D000962:Antimalarials; D011804:Quinolines; D015761:4-Aminopyridine; D000109:Acetylcholine; D002118:Calcium; D015767:Mefloquine