目的：研究胞外不同Ｃａ２＋浓度对豚鼠心室肌细胞钠钙交换电流（Ｎａ＋Ｃａ２＋ｅｘｃｈａｎｇｅｃｕｒｅｎｔ，ＩＮａＣａ）的影响和阿米洛利（ａｍｉｌｏｒｉｄｅ）对该电流的作用。方法：建立缺血再灌时胞内Ｎａ＋超载的细胞模型，用膜片钳全细胞技术，记录ＩＮａＣａ的电流电压关系曲线。结果：阿米洛利１０－５，３×１０－５和１０－４ｍｏｌ·Ｌ－１，在＋５０ｍＶ时，对ＩＮａＣａ的抑制率分别是１５４％，２２６％和４０９％；在－８０ｍＶ时抑制率分别是５６％，１４６％和２３２％。结论：胞内Ｎａ＋超载确可引起Ｎａ＋Ｃａ２＋交换系统激活；阿米洛利对豚鼠心室肌细胞ＩＮａＣａ有抑制作用，且对ＩＮａＣａ外向成分的抑制作用大于对内向成分的抑制作用。 Objective: To study the effect of extracellular Ca2 + concentration on sodium-calcium exchange current (Na + Ca2 + exchangecurent, INaCa) in guinea pig ventricular myocytes and the effect of amiloride on this current. Methods: To establish a cell model of intracellular Na + overload during ischemia / reperfusion, and record the current-voltage curve of INa-Ca using patch-clamp whole cell technique. Results: The inhibitory rates of amiloride at 10-5, 3 × 10-5 and 10-4 mol·L-1 at +50 mV were 154%, 226% and 409, respectively %; At -80mV inhibition rates were 5.6%, 14.6% and 23.2%. CONCLUSION: Intracellular Na + overload can indeed activate Na +Ca2 + exchange system. Amiloride can inhibit the INaCa in guinea pig ventricular myocytes, and inhibit the INaCa extrinsic component more than the inwardinhibitory component.