Wistar大鼠长期高盐摄入对心脏功能的影响及机制探讨

摘要

目的:研究Wistar大鼠长期高盐摄入对心脏功能的影响特点及机制.方法:购Wistar大鼠27只(3周龄),随机分成高盐饲养组14只和正常饲养组13只,饲以含盐量不同饲料.两组持续喂养18周(即21周龄)后,均进行血压、血浆醛固酮浓度、血浆血管紧张素Ⅱ浓度、左心室重量指数、心脏形态学检查以及心功能测定.结果:在实验前(3周龄),两组实验动物鼠尾收缩压差异无统计学意义(P>0.05).实验满8周(11周龄)起,高盐饲养组大鼠收缩压明显比正常饲养组高(P<0.05),并持续至实验满16周(19周龄),且随饲养时间延长,收缩压差值进一步加大,差异有统计学意义(P<0.05).实验满18周时(21周龄),高盐饲养组的左心室重量指数、平均心室舒张末期压、平均心率均比正常饲养组高,差异有统计学意义(P<0.01或P<0.05);高盐饲养组的血浆醛固酮浓度、血浆血管紧张素Ⅱ浓度、平均收缩间期均比正常饲养组低,差异有统计学意义(P<0.01或P<0.05);两组的体重、平均舒张间期、左心室压力最大上升速率及下降最大速率比较差异均无统计学意义(P均>0.05).心肌Masson染色后的形态学检查提示高盐饲养组大鼠心肌间隙较正常饲养组减少,心肌间质内可见散在蓝色条索状胶原纤维.应用双变量相关分析,结果显示左心室重量指数与心率呈正相关(r=0.729,P<0.05);血管紧张素浓度与平均舒张间期呈负相关(r=-0.736,P<0.05).结论:本实验提示,在长期高盐饮食下,机体血压持续升高,心率增快,血管循环肾素-血管紧张素-醛固酮系统受到抑制,但心室仍然出现心肌重构,心功能表现为心率增快,心脏收缩间期缩短,心室舒张末期压升高.%Objective:To study the effect of long-term high salt diet on cardiac functional changes with its mechanism in rats.rnMethods: The experimental rats were divided as Normal diet group, n = 13 and High salt diet group, n = 14. All rats were fed for 18 weeks,and their blood pressure,plasma concentrations of aldosterone( ALD ),angiotensin Ⅱ( Agn Ⅱ ),left ventricular mass index, cardiac function and morphology were measured and compared respectively.rnResults: The baseline tail systolic blood pressure was similar between two groups,P>0. 05. With 8 weeks feeding,High salt diet group presented increased blood pressure than Normal diet group, P<0. 05, this result lasted until 16 weeks of feeding. By the end of experiment, the left ventricular mass index, mean ventricular end-diastolic pressure and mean heart rate were higher in High-salt diet group than those in Normal diet group,P<0. 01 or P<0. 05. The concentrations of plasma ALD,AngII and the average heart contraction interval were lower in High-salt diet group than those in the Normal diet group,P<0. 01 or P<0. 05. Masson staining showed that high-salt diet rats had thinner myocardial gap and scattered collagen fibers in the myocardial intersti-tials. Bivariate correlation analysis indicated that left ventricular mass index was positively related to heart rate( r = 0. 729, P<0. 05 ),Ang Ⅱ was negatively related to average diastolic interval( r = -0. 736,P<0. 05 ).rnConclusion: Long-term high-salt diet rats have increases blood pressure and ventricular myocardial remodeling with cardiac functional changes as increased heart rate, shortened systolic interval and elevated left ventricular end-diastolic pressure.