氯沙坦对心肌梗死大鼠压力反射敏感性的影响

Effect of Losartan on baroreflex sensitivity in conscious rats after myocardial infarction

目的通过测定实验心肌梗死大鼠压力反射敏感性及口服氯沙坦对压力反射敏感性的作用,探讨血管紧张素Ⅱ受体拮抗剂对心肌梗死后自主神经功能的影响。方法开胸结扎大鼠冠状动脉制作心肌梗死模型,采用新福林法测定假手术安慰剂大鼠和心肌梗死安慰剂大鼠术后3天和28天的压力反射敏感性水平。氯沙坦组大鼠给予氯沙坦5mg/kg/天灌胃,28天时进行压力反射敏感性测定。结果手术后3天和4周时,两假手术组大鼠压力反射敏感性无明显差异。两心肌梗死组大鼠压力反射敏感性也无显著差异,但较假手术组明显降低(P<0.01);氯沙坦组大鼠压力反射敏感性较心肌梗死组明显增加(P<0.01),与假手术组差异无显著性意义。线性回归分析显示压力反射敏感性与心率、平均动脉压、左心室舒张末压之间无相关性。结论心肌梗死大鼠在术后3天时压力反射敏感性显著降低并持续至4周。氯沙坦能够增加心肌梗死大鼠的压力反射敏感性,而且这种影响独立于其改善血流动力学作用之外。

Objective To observe alteration of baroreflex sensitivity (BRS) in conscious rats after AMI and effect of Losartan (ATI receptor antagonist) on BRS. Methods MI was induced by ligated left coronary artery of rats.Then animals were studied 3 and 28 days after sham operation(SH) and MI. BRS was determined by linear regression of R-R interval vs arterial pressure change induced by methoxamine(intravenous bolus). Results After 3 days and 28 days of SH and MI , there were no significant difference in BRS between two SH groups or two MIC(MI rats treated with distilled water ) groups.Comparing with SH group, BRS in MIC group was markedly decreased(P<0.01). BRS was increased in MIL(treated with Losartan) group(P<0.01),compared with MI group,and had no significant difference between MI-L group and SH group. Moreover,no linear relationship was founded between BRS and hemodynamic variables. Conclusion Decrease of BRS was found in conscious rats 3days after MI, and impairment of BRS continued to 4 weeks after MI. Losartan could increase BRS in MI rats ,which was not directly due to improvement of hemodynamic variables.