RNA干扰血管紧张素转换酶对自发性高血压大鼠血压及心肌重构的影响

目的 用RNA干扰技术下调血管紧张素转换酶(ACE)表达,观察其对自发性高血压大鼠血压及心肌重构的影响.方法 自发性高血压大鼠随机分为3组,即空白对照组(尾静脉注射生理盐水),病毒对照组(尾静脉注射对照腺病毒),治疗组[尾静脉注射表达ACE基因特异性短发夹RNA(shRNA)的重组腺病毒载体],同时设WKY正常血压对照组.以上各组大鼠均于实验的第1、16天各注射1次.干预前后检测尾动脉压的变化.于首次注射后第3天,用RT-PCR及Western blot法检测心肌、主动脉组织中ACE mRNA及蛋白的表达,ELISA法检测血清中ACE的含量.实验结束时,检测左心重/体重及心肌胶原蛋白的含量,并用透射电镜观察心肌超微结构的变化.结果 治疗组于每次注射后,尾动脉压均明显下降22 mm Hg(1 mm Hg=0.133 kPa)左右,单次注射后降压作用至少可持续14 d,累积降压幅度达38 mm Hg左右,而空白对照和病毒对照组血压则持续升高.治疗组心肌、主动脉组织中ACE mRNA及蛋白表达明显低于空白对照组和病毒对照组(P＜0.05),而与WKY组比较差异无统计学意义.治疗组血清ACE含量(16.37±3.90)ng/ml也明显低于空白对照组(48.26±1.50)ng/ml和病毒对照组(46.67±2.82)ng/ml,P＜0.05,而与WKY组(14.88±3.15)ng/ml比较差异无统计学意义.治疗组左心重/体重与心肌胶原蛋白含量[2.24±0.19与(1.283±0.019)μg/mg]明显低于空白对照组[3.21±0.13与(1.686±0.013)μg/mg]和病毒对照组[3.13±0.12与(1.682±0.009)μg/mg],P均＜0.05,但还未降到WKY组水平[2.06±0.11与(1.257±0.019)μg/mg].电镜观察显示治疗组心肌超微结构得到了明显改善.结论 RNA干扰可有效下调ACE表达,降低自发性高血压大鼠血压,改善心肌重构.RNA干扰有望成为高血压病基因治疗的新方法.

Effects of RNA interference targeting angiotensin-converting enzyme on the blood pressure and myocardial remodeling in spontaneously hypertensive rats

Objective To investigate the effects of RNA interference(RNAi)targeting angiotensinconverting enzynle(ACE)on the blood pressure and myocardial remodeling in spontaneously hypertensive rats(SHRs).Methods Saline(control),adenovirus(Ad5)and recombinant adenoviral vectors(Ad5-ACE-shRNA expressing ACE gene-specific shRN)were randomly administered by caudal intravenation to SHRs(n=12 each group)at day 1 and day 16.Normotensive Wistar-Kyoto rats(WKY)served as normal controls.Systolic blood pressure(SBP)of the caudal artery was measured daily.Expressions of ACE at mRNA and protein levels in myocardium and aorta were evaluated by RT-PCR and Western blot respectively,ACE serum concentration was measured by ELISA at day 3(n=6 each group).The ratio of left ventricular to body weight(LVW/BW),myocardial collagen content were measured and myocardial uhrastrueture observed under transmission electron microscope at the study end.Results Ad5-ACE-shRNA injection significantly reduced SBP(-22 mm Hg,1 mm Hg=0.133 kPa)and the antihypertensive effect could last at least 14 davs post each injection.SBP was not affected by saline and Ad5 injections.ACE expressions at mRNA and Drotein levels at myocardium and aorta as well as serum ACE were significantly decreased in Ad5-ACE-shRNA treated SHRs compared to that in saline and Ad5 groups(all P＜0.05)and was coinparable to that in WKY group(P＞0.05).The LVW/BW ratio(2.24±0.19)and myocardial collagen content[(1.283±0.019)μg/mg]in Ad5-ACE-shRNA treated SHRs were also significantly lower than those in saline treated[3.21±0.13 and (1.686±0.013)μg/mg,both P＜0.05]and Ad5 treated SHRs [3.13 ±0.12,(1.682±0.009)μg/mg,both P＜0.05]but still higher than those of WKY group[2.06±0.11,(1.257±0.019)μg/mg,both P＜0.05].Myocardial uhrastructure was also significantly improved in Ad5-ACE-shRNA treated SHRs compared to saline and Ad5 treated SHRs.Conclusion RNAi targeting ACE gene significantly inhibited the expressions of ACE at mRNA and protein levels and resuhed in prolonged antihypertensive effects and myocardial uhrastructure improvements in this SHR model.