[Effect of diethylamine analog of ethmozine on parameters of fast sodium current in normal and depolarized myocardial fibers].
The effect of a diethylamine analog of ethmozine (DAAE) on fast sodium current of normal and depolarized frog atrial trabeculae was studied by means of the double sucrose gap technique. The depolarization of the fibers was produced both by increasing extracellular potassium concentration up to 8 +/- 9 mM and by current passing. The resting potential of normal fibers was within the range of 75-80 mV, and the depolarized one was within 65 +/- 60 mV. DAAE (8 X 10(-7) g/ml) reduced sodium conductivity, slowed inactivation and reactivation of fast sodium current and shifted the steady-state activation curve (h infinity) to a more negative potential, but the steady-state activation curve (m infinity) to a more positive potential. All these effects were expressed more considerably in the depolarized fibers. The depressing ability of DAAE is assumed to be due to high concentration of the drug in the membrane owing to its high solubility in lipids. The slowing of sodium reactivation and inactivation shows the existence of a receptor for DAAE linked with a h-gate. Prolonged antiarrhythmic action is accounted for by a very slow recovery of sodium current after the drug superfusion. A stronger effect of DAAE on sodium current in the depolarized fibers is likely to point to its selective action on ischemic tissue.
D000818:Animals; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D016293:Moricizine / Q000031:analogs & derivatives*; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D010477:Perfusion; D010640:Phenothiazines / Q000494:pharmacology*; D011892:Rana catesbeiana
D007473:Ion Channels; D010640:Phenothiazines; C027240:diethylamino-ethmozine; D016293:Moricizine
Deĭstvie diétilaminovogo analoga étmozina na parametry bystrogo natrievogo toka normal'nykh i depoliarizovannykh volokon miokarda.