Effects of Angiotensin-(1-7) on Angiotensin Ⅱ and Its Receptor in Pressure-overloaded Rats / 中国医师杂志

ABSTRACT

Objective To investigate the effects of angiotensin-(1-7) on angiotensin Ⅱ and its receptor in pressure-overloaded rats. Methods Rat models of pressure-overloaded heart was induced by constriction of abdominal aorta. Forty-five male Sprague Dawley rats were randomized into sham-operated group,model control group and angiotensin-(1-7) treatment group. They were treated with intravenous infusion of 25?g/kg/h angiotensin-(1-7) or same volume of saline after operation. After the treatment for 4 weeks, the ratio of left ventricular weight to body weight(LVW/BW)was determined, angiotensin Ⅱ concentrations in plasma and myocardium were measured by radioimmunoassay, and the expression levels of type 1(AT_1) and type 2(AT_2) angiotension Ⅱ receptor mRNA in left ventricular myocardium were assessed by RT-PCR. Results Compared with sham-operated group, myocardial angiotensin II concentration and AT_1 receptor mRNA level in model control group obviously increased 4 weeks after operation. Compared with model control group, angiotensin II concentrations in plasma and myocardium in angiotensin-(1-7) treatment group had not obvious change, the expression level of myocardial AT_1 receptor mRNA decreased, and the ratio of LVW/BW obviously decreased. There was no significant difference in myocardial AT_2 receptor mRNA level among the three groups. Conclusion Exogenous angiotensin-(1-7) can attenuate cardiac hypertrophy possibly by inhibiting myocardial AT_1 receptor mRNA expression in pressure-overloaded rats.