[Adrenaline-induced autorhythmic activity in the isolated atrial myocardium of mitral stenosis patients and its suppression by etmozin and ethacizin (the diethylamino analog of etmozin)].
The authors studied the effect of the new Soviet antiarrhythmic phenothiazine drugs etmozine and etacizine (a diethylamine analog of etmozine) on the adrenaline-induced (10(-4)M) autorhythmic activity of the myocardium of the atria of patients with mitral stenosis. Different types of autorhythmic activity occurring in the myocytes of the atria of patients with mitral stenosis are described. It was established that neither etmozine nor etacizine produce any significant changes in the action potential (AP) amplitude and in the maximal diastolic potential of spontaneous AP. However, the action of etacizine on the rate of diastolic depolarization and the frequency of AP discharges was more remarkable. Moreover, etacizine (10(-5) g/ml) completely suppressed autorhythmic activity of the myocytes in 60% of the preparations whereas etmozine administered at the same concentration only in 33%. It is assumed that substantially higher efficacy of etacizine in the reduction of the adrenaline-induced autorhythmic activity in human atrial fibers as compared with etmozine is explained by the action of etacizine not only on the fast sodium current but also on the slow calcium current.
D000200:Action Potentials / Q000187:drug effects; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical; D004837:Epinephrine / Q000494:pharmacology*; D006325:Heart Atria / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008946:Mitral Valve Stenosis / Q000503:physiopathology*; D016293:Moricizine / Q000031:analogs & derivatives; D009200:Myocardial Contraction / Q000187:drug effects*; D010640:Phenothiazines / Q000494:pharmacology*
D000889:Anti-Arrhythmia Agents; D010640:Phenothiazines; C027240:diethylamino-ethmozine; D016293:Moricizine; D004837:Epinephrine
Vyzvannaia adrenalinom avtoritmicheskaia aktivnost' v izolirovannom miokarde predserdiĭ bol'nykh mitral'nym stenozom i ee podavlenie étmozinom i étatsizinom (diétilaminovym analogom étmozina).