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目的研究奥美沙坦对肾血管性高血压大鼠心肌肥厚的作用,探讨其对病理性肥厚心肌ACE2/Ang(1-7)/Mas的作用。方法清洁级雄性SD大鼠68只,随机分为假手术组(S)18只、两肾一夹组(two kidney one clip,2K1C)50只。S组分离左肾动脉而不缩窄;实验组采用2K1C方法制备高血压模型。术后第4周末采用尾动脉袖法测量大鼠血压,造模成功大鼠(44只)随机分为2K1C+蒸馏水组(K)22只与2K1C+奥美沙坦组(O)22只。术后第5周始O组以奥美沙坦3mg.kg-1.d-1灌胃;K组每天以等体积蒸馏水灌胃。术后第8、12、14周,测量大鼠血压,超声心动图观察心脏结构及功能,酶联免疫吸附技术(ELISA)检测动脉血浆Ang(1-7)水平。实时荧光定量PCR检测心肌血管紧张素转换酶2(ACE2)及Ang(1-7)受体Mas mRNA表达,免疫印迹技术检测P-ERK1/2、Mas及ACE2蛋白水平。结果 (1)术后4、8、12、14周K组收缩压明显升高,药物灌胃后明显降低(P均<0.01);(2)术后第8、12、14周,K组大鼠舒张末期及收缩末期室间隔厚度、舒张末期及收缩末期左心室后壁厚度、左心室质量指数均明显增加,药物灌胃后明显改善(P均<0.01);(3)K组血清Ang(1-7)水平在8、12周时明显升高(P均<0.01),14周时恢复正常(P>0.05),与K组比,O组Ang(1-7)水平8周时降低,在12、14周时明显升高(P均<0.01);(4)K组ACE2及Mas基因及蛋白水平8周时均上调,12、14周时均下调,p-ERK1/2各时间段表达均升高(P均<0.01);与K组比较,O组两基因及蛋白水平8周时明显降低,在12、14周时明显升高,P-ERK1/2各时间段表达均降低(P均<0.01)。结论 2K1C法成功制作肾性高血压大鼠模型并导致明显左心室肥厚;奥美沙坦明显降低肾性高血压大鼠血压、改善左心室肥厚,抑制血清Ang(1-7)水平及组织Mas、ACE2基因与蛋白水平下调。其改善心肌肥厚作用与其作用于Ang(1-7)/Mas/ERK1/2信号通路有关。
Objective To investigate the effect of olmesartan on cardiac hypertrophy in renovascular hypertensive rats and its effect on ACE2 / Ang (1-7) / Mas in hypertrophic myocardium. Methods Sixty clean male Sprague-Dawley rats were randomly divided into sham-operation group (S), 18 and two kidney one-clip (2K1C) groups. S group isolated from the left renal artery without constriction; experimental group using 2K1C method for the preparation of hypertension model. At the end of the fourth week, the blood pressure was measured by the tail artery cuff method. Forty rats were randomly divided into 22 rats in 2K1C + distilled water group (K) and 22 rats in 2K1C + olmesartan group (O). At the fifth week after operation, O group was orally administered with 3 mg.kg-1.d-1 of olmesartan. Group K was orally administered with equal volume of distilled water daily. Blood pressure was measured at 8th, 12th and 14th week after operation. The structure and function of heart were observed with echocardiography. The level of Ang (1-7) in arterial plasma was detected by enzyme - linked immunosorbent assay (ELISA). The expression of Angiotensin-converting enzyme 2 (ACE2) and Ang (1-7) receptor Mas mRNA were detected by real-time fluorescence quantitative PCR. The protein levels of P-ERK1 / 2, Mas and ACE2 were detected by Western blotting. Results (1) After 4, 8, 12 and 14 weeks, the systolic blood pressure in group K was significantly increased (P <0.01); (2) After 8, 12 and 14 weeks, The end-diastolic and end-systolic ventricular septal thickness, end-diastolic and left ventricular posterior wall thickness, left ventricular mass index were significantly increased (P <0.01); (3) (1-7) significantly increased at 8 and 12 weeks (all P <0.01), and returned to normal at 14 weeks (P> 0.05). Compared with K group, the levels of Ang (1-7) (P <0.01). (4) ACE2 and Mas gene and protein levels in group K were both up-regulated at 8th week and down-regulated at 12th and 14th week respectively. The expressions of p-ERK1 / 2 (P <0.01). Compared with K group, the two genes and protein levels in O group decreased significantly at 8th week, increased significantly at 12th and 14th week, and decreased at P-ERK1 / 2 (P All <0.01). Conclusion 2K1C method successfully produced rat model of renal hypertension and lead to significant left ventricular hypertrophy. Olmesartan significantly reduced blood pressure, improve left ventricular hypertrophy, inhibit serum Ang (1-7) level and tissue Mas, ACE2 gene and protein levels down. Its role in improving cardiac hypertrophy is related to Ang (1-7) / Mas / ERK1 / 2 signaling pathway.