盐负荷对SHR左心室AT1和AT2受体表达的影响

Expression of AT1 and AT2 in Left Ventricular Myocardium of Spontaneously Hypertensive Rats with Salt Load

目的以自发性高血压大鼠(SHR)为研究对象,探讨盐负荷对心肌局部胶原成分、心肌细胞凋亡、血管紧张素Ⅱ受体AT1和AT2蛋白表达的影响。方法成年雄性SHR 60只,随机分为低盐(n=30)和高盐饮食组(n=30),分别用9g/L Na Cl和40g/L Na Cl干预3周。鼠尾法测量血压,尿钠测定;称体重,石蜡切片Mallory染色法观察心肌间质纤维化程度,TUNNEL法检测凋亡,免疫组化SABC法测定AT1和AT2蛋白表达。结果高盐负荷后SHR大鼠的血压、尿钠明显升高(P<0.05);左心室肌凋亡增多,胶原纤维沉积亦增多(P<0.05);盐负荷均能显著增加左心室AT1和AT2表达(P<0.01),AT1/AT2比值增大(P<0.05)。结论高盐负荷可导致SHR大鼠左心室肌重塑,心肌组织局部血管紧张素Ⅱ受体(ATR)的改变可能是SHR大鼠血管壁重塑的机制之一,减少盐的摄入对预防高血压引发的心肌肥厚、心衰的发生和发展有着重要的意义。

Objective To investigate the influences of high salt load on collagen fibers, apoptosis and expressions of angiotensin receptor-1（AT1） and angiotensin receptor-2（AT2） in the development of remodeling in left ventricular myocardium of spontaneously hypertensive rats. Methods Sixty male SHR were randomly divided into normal-salt group（9 g/L Na Cl） or high-salt one（40 g/L Na Cl）, fed for 3 weeks. Before and after 3-week intervention of diet, the systolic blood pressures（SBP） and urine sodium of SHR were measured and analyzed. After salt load, the proteins of AT1 and AT2 in left ventricular myocardium were detected by immunohisto-chemistry SABC staining in paraffin sections. The sediments of collagen fibers were detected using Mallory three-color staining. The apoptosis were detected using TUNEL method. Results High-salt diet induced a significant increase of SBP and urine sodium（P0.01）. The apoptosis and sediment of collagen fibers had this trends. There were increasing expressions in AT1（P〈0.01）, AT2（P〈0.05） and the ratio of them（P〈0.05） in left ventricular myocardium. Conclusion Increasing expression of AT1, AT2 protein and ratio of them in ventricular myocardium of SHR may be one of mechanisms of remodeling induced by salt load.