一种新的钠-钙交换电流记录方法及阿米洛利的作用

A NOVEL METHOD OF RECORDING Na + Ca 2+ EXCHANGE CURRENT AND EFFECT OF AMILORIDE ON THE CURRENT IN GUINEA PIG VENTRICULAR MYOCYTES

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。

AIM: To study the effects of various extracellular Ca 2+ concentration and amiloride on Na + Ca 2+ exchange current(I Na Ca ) in guinea pig ventricular myocytes. METHODS: Through setting up the model of intracellular Na + overload during myocardial ischemia and reperfusion, the current voltage relationship of I Na Ca was recorded using whole cell patch clamp technique with a declining ramp pulse protocol. RESULTS: Amiloride can block the I Na Ca significantly. At potential of +50 mV, amiloride 10 -5 , 3×10 -5 and 10 -4 mol·L -1 inhibited the I Na Ca by 15 4%, 22 6% and 40 9%, respectively; at potential of -80 mV amiloride inhibited I Na Ca by 5 6%, 14 6% and 23 2%, respectively. CONCLUSION: Intracellular Na + overload can activate Na + Ca 2+ exchange system which can be affected by extracellular Ca 2+ . Amiloride can block I Na Ca in guinea pig ventricular myocytes. Its inhibition effects on outward currents were greater than those on inward currents.