血管紧张素转换酶-2在压力超负荷大鼠心肌中的表达及替米沙坦干预的实验研究

摘要

Objective To study the effect of hypertension and telmisartan treatment on the protein and gene expression of cardiac angiotensin-converting enzyme 2(ACE2)in pressure-overloaded rats.Methods Coarctation of suprarenal abdominal aorta was reproduced in 8 week-old male Sprague-Dawley(SD)rats and then randomized into 4 groups,including a sham group(n=15),a suprarenal aortic coarctation group (model group,n=12),a suprarenal aortic coarctation with low-dose Telmisartan treatment group(low-dose gavaged 24 hours before the operation and once every day afterwards for 3 weeks.At the end of 3 weeks,the concentrations of angiotensin(Ang Ⅱ)in plasma and myocardium were measured by radioimmunoassay.Changes in both protein quantity and gene expressions of both ACE2 and ACE were determined by Western blotting analysis and reverse transcription-polymerase chain reaction(RT-PCR)technique,respectively.Results Suprarenal abdominal aortic coarctation induced a significant increase in the plasma and myocardium Ang Ⅱ concentration[plasma:(495.1±55.6)ng/L vs.(269.2±39.5)ng/L,myocardium:(103.6±23.7)ng/g vs.(49.5±13.5)ng/g,both P＜0.01] and expressions of gene and protein of ACE(P＜0.01)and ACE2(P＜0.05).Telmisartan further increased the concentration of Ang Ⅱ in plasma and myocardium in a dose-dependent manner(plasma:(702.2±40.6)ng/L vs.(612.6±35.5)ng/L,myoeardium(211.5±21.5)ng/g vs.(189.6±43.6)ng/g,both P＜0.05＝,and induced a dose-dependent increase in both protein and gene expression of ACE2(protein 1.16±0.06 vs.0.79±0.04,gene 0.54±0.08 vs.0.41±0.04,both P＜0.05＝.Expression of ACE2 protein in low-dose and high-dose groups was increased by 1.0 and 1.58 folds respectively,and gene was increased by 1.3 and 1.6 folds(all P＜0.05＝.The expression of ACE protein and gene in model group increased significantly(protein:2.10±1.07 vs.1.02±0.05,gene:1.93±0.09 vs.0.26±0.09,both P＜0.01＝.Telmisartan had no significant effect on ACE gene and protein expressions(both P＞0.05).Conclusion Suprarenal abdominal aortic coarctation induced a significant increases of ACE and ACE2 gene and protein expressions.Telmisartan induces a dose-dependent increases of cardiac ACE2 gene and protein expression,which may be the mechanism of its therapeutic effects.%目的 探讨血管紧张素转换酶-2(ACE2)在压力超负荷大鼠心肌中的表达,以及替米沙坦对其表达的影响.方法 将8周龄雄性SD大鼠60只随机分为假手术组、模型组和替米沙坦低、高剂量治疗组.制备腹主动脉缩窄动物模型.替米沙坦高、低剂量组大鼠术前1 d开始分别给予替米沙坦10 mg·kg-1 ·d-1和2 mg·kg-1·d-1管饲,假手术组和模型组则饲以等量生理盐水,每日1次,持续3周.3周后留取血浆和心肌组织标本,以放射免疫法检测血浆和心肌血管紧张素Ⅱ(Ang Ⅱ)浓度;以逆转录-聚合酶链反应(RT-PCR)检测心肌中ACE2和ACE的mRNA表达;以蛋白质免疫印迹法(Western blotting)检测其蛋白表达.结果 与假手术组比较,模型组血浆及心肌中Ang Ⅱ浓度明显增高(血浆(495.1±55.6)ng/L比(269.2±39.5)ng/L,心肌(103.6±23.7)ng/g比(49.5±13.5)ng/g,P均＜0.01],用替米沙坦干预可升高其水平(P均＜0.05),高剂量组显著高于低剂量组[血浆(702.2±40.6)ng/L比(612.6±35.5)ng/L,心肌(211.5±21.5)ng/g比(189.6±43.6)ng/g,P均＜0.053.模型组心肌ACE2蛋白及基因表达均增加(蛋白1.164±0.06比0.79±0.04,基因0.54±0.08比0.41±0.04,P均＜0.05).与模型组比较,替米沙坦干预使心肌ACE2表达增加,呈剂量依赖性,其中低、高剂量组ACE2蛋白表达分别增高1.0倍、1.6倍,基因表达分别增高1.3倍、1.6倍(P均＜0.05).模型组ACE蛋白及基因表达显著增加(蛋白2.10±1.07比1.02±0.05,基因1.93±0.09比0.26±0.09,P均＜0.01),替米沙坦对其表达无显著影响(P均＞0.05).结论 腹主动脉缩窄可显著上调心肌ACE和ACE2的蛋白及基因表达;替米沙坦可能通过上调其水平来发挥治疗作用.