[Decreased sodium conductance of the cardiomyocyte membrane: the cause of the negative inotropic action of quinidine-like anti-arrhythmia agents].
The action of tetrodotoxin on the guinea-pig muscle caused a decrease in the maximum rate of action potential, which was accompanied by a negative inotropic effect. The magnitude of such an effect correlated well with the decrease of sodium permeability, measured by the maximum rate of depolarization (r = 0,995). The effect was enhanced under the action of veratrine and diminished under that of isoproterenol. It was suggested that the negative inotropic effect of tetrodotoxin was the result of the inhibition on Na-Ca exchange due to diminished intracellular Na+ concentration.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D010210:Papillary Muscles / Q000187:drug effects; D011802:Quinidine / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D000889:Anti-Arrhythmia Agents; D007473:Ion Channels; D013779:Tetrodotoxin; D012964:Sodium; D011802:Quinidine
Umen'shenie natrievoĭ provodimosti membrany kardiomiotsitov--prichina otritsatel'nogo inotropnogo deĭstviia khinidinopodobnykh antiaritmicheskikh sredstv.