Effect of total flavones of sophora flavescens root on arrhythmia of cultured rat heart cells

Total flavones (TF) extracted from the root of Sophora flavescens Ait. were dissolved in l% Tween-80 (pH 7.8). The cardiomyocytes of newborn rats were cultured in Eagle MEM. TF 125-250 ug/ml in the medium caused a decrease of 48 ± (SD) 19% of the beating rate of cell clusters. Some cultured myocytes showed spon-taneous arrhythmias.When TF 125-250 ug/ml were added into the medium, the ar-thythmias of the cell clusters disappeared in 15/39 ex periments (38%) and the flutter and fibrillation were markedly diminished in 19 experiments (49%). Flutter and fibrillation were seen in 20/25 experiments in ouabain 15-50 nM. These irregular beatings disappeared after addition of TF in 5/20 experiments and diminished conspicuously in 5/20 experi-ments. Thus TF exerts a chronotropic and antiarrhythmic effect on cultured rat heart cells, but Tween-80 had no antiarrhythmic effect.