目的　观察KB R7943对豚鼠心室肌细胞Na+ Ca2 +交换电流 (INa Ca)的内向电流成分和外向电流成分的影响。方法　采用缺血再灌时胞内Na+超载的细胞模型 ,在同时记录内向、外向电流的双向离子条件下 ,用膜片钳全细胞技术 ,记录INa Ca的电流 电压关系曲线。结果　 10 -6和 10 -5mol·L-1KB R7943 ,在 + 5 0mV时 ,对INa Ca的抑制率分别是 2 9 4%和 6 1 7% ;在 - 80mV时抑制率分别是 2 2 1%和 5 6 9%。结论　KB R7943对豚鼠心室肌细胞INa Ca有抑制作用 ,但对外向成分和内向成分的抑制不具选择性。 Objective To observe the effects of KB R7943 on inward current component and outward current component of Na + Ca2 + exchange current (INa Ca) in guinea pig ventricular myocytes. Methods The cell model of intracellular Na + overload during ischemia / reperfusion was used to record the current-voltage curve of INa Ca with patch-clamp whole cell technique under bi-directional ion exchange with both inward and outward currents. Results The inhibitory rates of 10 -6 and 10 -5 mol·L-1 KB R7943 to INa Ca at +50 mV were respectively 294% and 61.7%, while those at -80 mV were respectively 21% And 59 6%. Conclusion KB R7943 inhibits INa Ca in guinea pig ventricular myocytes, but it is not selective for the inhibition of extrinsic and introgressive components.