缬沙坦对心力衰竭大鼠心肌细胞钙通道和钠-钙交换体电流的影响

目的：探讨缬沙坦对心力衰竭大鼠心肌细胞钙通道和钠-钙交换体电流的影响。 方法： 结扎大鼠冠状动脉左前降支8周后，复制心力衰竭模型，随机分2组，即心力衰竭治疗组与心力衰竭对照组，分别用缬沙坦和安慰剂治疗，另设假结扎对照组。治疗16周后，用急性酶解法获得单个大鼠心室肌细胞和标准全细胞膜片钳技术记录通道电流。 结果： (1) 心力衰竭对照组左室舒张末压（LVEDP） 和细胞膜电容（Cm）明显大于假结扎对照组（P<005），左室最大收缩压（LVSP）和左室内压的最大上升和下降速率（±dp/dtmax）明显少于假结扎对照组（P<005）；而心力衰竭治疗组LVSP和±dp/dtmax明显高于心力衰竭对照组（P<005），LVEDP和Cm明显少于心力衰竭对照组（P<005），3组心率（HR）和血压(BP)无明显差异（P>005）。（2）心力衰竭对照组钙通道电流密度峰值明显少于假结扎对照组(P<005)，心力衰竭治疗组明显大于心力衰竭对照组(P<005)，但激活电位、峰电位和翻转电位差异均无显著(P>005)。（3）3组钙通道电流激活、失活和复活动力学特征均无显著差异（P>005）。（4）心力衰竭对照组钠钙交换体电流密度明显大于假结扎对照组（P<005），心力衰竭治疗组明显少于心力衰竭对照组（P＜005）。 结论：缬沙坦治疗能明显减缓充血性心力衰竭的心功能恶化和心肌肥厚，可能与改善心力衰竭心肌细胞膜钙通道电流和钠钙交换电流变化有关。

Effect of valsartan on calcium channel current and sodium-calcium exchanger current in heart failure rats

AIM: To determine the effects of valsartan on calcium channel and sodium-calcium exchanger current in isolated ventricular myocytes of congestive heart failure (CHF) rats. METHODS: Eight weeks after coronary ligation, the rats with heart failure were confirmed by measuring the hemodynamic parameters and divided randomly into the group treating with valsartan (CHF-T, 20 mg/kg) and placebo (CHF-C). Sham-operated group rats served as negative controls (PS). Twelve weeks later, 6 rats were selected randomly for the study of ion channel. Single ventricular myocytes of rats were isolated by enzymatic dissociation. The whole-cell patch-clamp recording technique was used to record calcium channel current and sodium-calcium exchanger current. RESULTS: (1) In the hemodynamic variables, HR and blood pressure were not significantly different in three groups. Compared CHF-C with PS group, LVEDP and Cm increased, LVSP and ±dp/dtmax decreased (P<005). Compared CHF-T group with CHF-C group, LVEDP and Cm decreased, LVSP and ±dp/dtmax increased (P<005). (2) Calcium channel current in CHF-C decreased significantly (P<005). Calcium channel current in CHF-T group was larger significantly than that in CHF-C group (P<005). (3) The activation, inactivation and recovery curves were not altered in 3 groups (P>005). (4) Na+-Ca2+ exchanger current in CHF-C group increased significantly. Na+-Ca2+ exchanger current in CHF-T group was smaller significantly than that in CHF-C group. However, CHF-T group and PS group were not significantly different. CONCLUSION: Administration of valsartan is effective in preventing from cardiac function deterioration, increases calcium channel current and decreases Na+-Ca2+ exchanger current in ventricular myocytes of heat failure rats.