title: Paradoxical actions of quinidine in hyperpermeable heart cells.
abstract: The effect of quinidine on the inotropic state was examined using small fragments of hyperpermeable ventricular muscle in vitro. In concentrations of 10(-5) and 10(-4) M, quinidine had no effect on the force of spontaneously contracting fibers. At a concentration of 10(-3) M, contractile force increased by at least twofold. We conclude that the negative inotropic action of quinidine is not by a direct action on intracellular organelles of the heart.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002415:Cats; D002463:Cell Membrane Permeability; D006224:Cricetinae; D004533:Egtazic Acid / Q000494:pharmacology; D008297:Male; D008647:Mesocricetus; D009124:Muscle Proteins / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D011802:Quinidine / Q000494:pharmacology*
chemical_list: D009124:Muscle Proteins; D004533:Egtazic Acid; D011802:Quinidine; D002118:Calcium