Lack of relation between the ventricular refractory period prolongation by amiodarone and the thyroid state in rats.

摘要: We investigated the possibility that prolongation of ventricular effective refractory period (VERP) by amiodarone might be mediated, at least in part, inhibition thyroid influence on heart. VERP values were measured vitro isolated septal preparations obtained from control, thyroidectomized and thyroxine (tetraiodothyronine; T4)- or triiodothyronine (T3)-treated rats. Differences heart between these groups assessed changes myosin isozyme (V1, V2, V3) pattern. measurements also done similar treated with for 7 days (50 mg/kg/day i.p.). tended to increased thyroidectomy was significantly reduced T4 T3 treatment when compared control group. Amiodarone prolonged (33.4 +/- 1.9 45.0 4.5 msec), (39.9 1.7 48.3 2.8 T4-treated (26.2 1.0 37.4 1.3 msec) T3-treated rats (25.6 1.1 34.3 msec). However, magnitudes not different among four groups. The action potential duration its VERP. myocardial concentrations desethylamiodarone produced a significant reduction serum levels an increase reverse levels. Thus, class III affected, present model, experimental modification