不同浓度钠盐饮食对自发性高血压大鼠心脏结构及功能的影响

Effects of dietary sodium contents on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats

目的观察不同浓度钠盐饮食对自发性高血压大鼠(SHR)血压及左心室肥厚的影响,并探讨其可能机制。方法将30只SHR大鼠随机平均分成3组:(1)高盐饮食(SHRh)组,饮用含4%氯化钠溶液;(2)正常盐饮食(SHRn)组,饮用0.9%氯化钠溶液;(3)低盐饮食(SHRl)组,饮用含0.4%氯化钠溶液。另以10只Wistar大鼠作为对照组,饮用0.9%氯化钠溶液。适应性喂养1周,实验喂养12周。测定大鼠血压动态变化及左室重量指数(LMI),采用RT-PCR法测定左心室心肌组织B型利钠肽(BNP)RNA基因表达,并电镜观察左心室心肌组织变化。结果 SHR各组大鼠与对照组大鼠比较血压明显升高[SHRh组(226.33±7.81)mm Hg,SHRn组(209.66±10.78)mm Hg,SHRl组(223.83±9.62)mm Hg,对照组(138.14±12.85)mm Hg,均P<0.05],LMI升高(SHRh组16.35±2.54,SHRn组9.55±0.88,SHRl组11.17±2.20,对照组6.44±1.14,均P<0.05);SHRh组及SHRl组较SHRn组后期血压更高,LMI也相应升高,左心室BNP-RNA基因表达增加(SHRh组1.14±0.15,SHRl组1.22±0.51,SHRn组0.80±0.51,均P<0.05)。电镜观察显示SHRh组及SHRl组心肌细胞结构破坏。结论钠盐对SHR大鼠高血压及心脏结构功能的影响存在"J曲线"现象。

Objective To investigate the effects of dietary sodium contents on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats（SHRs）.Methods Thirty spontaneously hypertensive rats were randomly divided into 3 groups：high salt diet SHR group（drinking 4%NaCl solution,SHRh,n=10）,normal salt diet SHR group（drinking 0.9%NaCl solution,SHRn,n=10）,low salt diet SHR group（drinking 0.4%NaCl solution,SHR1,n=10）.Wistar rats were used as control group（drinking 4%NaCl solution,n=10）.After 1 wk of adaptive feeding,blood pressure was measured over 12 wks and left ventricular hypertrophy was examined by left ventricular mass index（LMI）.RT- PCR was used to determine B- type natriuretic peptide（BNP）mRNA expression in left ventricle,and scan electron microscope（SEM） was used to observe the changes of left ventricular myocardium.Results Compared with control group,the blood pressure of SHRs increased significantly[SHRh（226.33 ± 7.81）mmHg,SHRn（209.66 ± 10.78）mmHg,SHR1（223.83 ± 9.62）mmHg,control group（138.14 ± 12.85）mmHg,P〈0.05],the left ventricular weight index was also increased（SHRh 16.35± 2.54,SHRn 9.55± 0.88,SHR1 11.17± 2.20,controls 6.44± 1.14,P〈0.05].In later period compared with SHRn,both SHRh and SHR1 showed higher blood pressure and left ventricular mass index,and the expression of BNP mRNA in left ventricle increased（SHRh 1.14＋ 0.15,SHR11.22± 0.51,SHRn 0.80± 0.51,P〈0.05）.SEM showed thatthe myocardial cell structure was damaged in SHRh and SHRlgroups.Conclusion The effects of salt stress on hypertension and left ventricular hypertrophy in SHR rats may present ＂J curve＂ phenomenon.