血管紧张素-(1-7)对腹主动脉缩窄大鼠的抗心肌肥厚效应

目的　探讨血管紧张素 (1 7)能否预防和减轻腹主动脉缩窄所诱导的大鼠心肌肥厚。方法　 45只大鼠随机分为假手术组、腹主动脉缩窄组、腹主动脉缩窄 +血管紧张素 (1 7)治疗组 ,每组 15只。在腹主动脉缩窄术后 1d开始 ,腹主动脉缩窄血管紧张素 (1 7)治疗组大鼠经置入式微量泵持续颈静脉给予血管紧张素 (1 7) ,给药剂量 2 5μg·kg- 1 ·h- 1 ,假手术组及腹主动脉缩窄组经微量泵只给予同量的生理盐水 ,4周后检测颈动脉血压、心率、血浆和心肌血管紧张素Ⅱ浓度、左心室重量指数和心肌胶原容积分数。结果　腹主动脉缩窄可导致颈动脉血压升高、心率加快、心肌血管紧张素Ⅱ浓度升高、左心室重量指数和心肌胶原容积分数增加 ;血管紧张素 (1 7)不改变腹主动脉缩窄所诱导增高的血压、心率和心肌血管紧张素Ⅱ浓度 ,但能明显减轻腹主动脉缩窄所诱导增高的左心室重量指数和心肌胶原容积分数。结论　外源性血管紧张素 (1 7)能减轻腹主动脉缩窄所诱导的大鼠心肌肥厚。其机制不是通过改变血流动力学或心肌血管紧张素Ⅱ浓度所致 ,可能与它抑制血管紧张素Ⅱ的细胞内信号转导有关。

Effects of angiotensin-(1-7) on myocardial hypertrophy in rats with abdominal aortic coarctation

Objective To investigate the effects of angiotensin-(1-7) on myocardial hypertrophy in rats with abdominal aortic coarctation.Methods Forty-five male Sprague Dawley rats were randomized to following treatment groups:(1)sham-operated,(2)aortic banding,(3)aortic banding+ angiotensin-(1-7).One day after surgery,intravenous infusion of angiotensin-(1-7) (25 μg·kg -1·h -1) or saline was started by minipump.Four weeks after treatment,carotid artery systolic and diastolic blood pressure,heart rate,plasma angiotensinⅡand myocardial angiotensinⅡlevels were measured,ratio of left ventricular weight to body weight(LVW/BW) and myocardial collagen volume fraction(CVF) were determined.Results Abdominal aortic banding resulted in significant increase in carotid artery systolic and diastolic blood pressure,heart rate,myocardial angiotensinⅡlevel,LVW/BW and CVF.Angiotensin-(1-7) significantly attenuated aortic banding-induced increase in LVW/BW and CVF,but it had no effect on aortic banding-induced increase in blood pressure,heart rate and myocardial angiotensinⅡlevel.Conclusion In male rats,angiotensin-(1-7) can attenuate myocardial hypertrophy induced by aortic banding.