O bloqueio do sistema renina-angiotensina atenua a remodelação cardíaca de ratos submetidos a estenose aórtica

Abstract

To assess the role of the AT1 receptor blocker and the angiotensin-converting enzyme inhibitor in cardiac remodeling induced by aortic stenosis in rats. Wistar rats were divided into the following 4 groups: 1) C--control (n=13); 2) AoS--aortic stenosis (n=11); 3) LIS--AoS treated with lisinopril, 20 mg/kg/day (n=11); and 4) LOS--AoS treated with losartan, 40 mg/kg/day (n=9). The treatments were initiated 3 days before surgery. After 6 weeks, the animals underwent echocardiographic study, and quantification of the hydroxyproline (HOP) concentration and the left ventricular (LV) myocyte cross-sectional area (CSA). Aortic stenosis induced an increase in left ventricular wall thickness. The LIS and LOS groups showed no difference as compared with the control group. The AoS and LIS rats had greater left atrial diameters than the control rats did, while no difference was observed in the LOS animals. The AoS animals had greater values of shortening percentage than control animals did. This fact was modified with neither LIS nor LOS. The cross-sectional area of the animals in the AoS group was greater than that in the control group. However, treatment with LOS and LIS attenuated the AoS-induced increase in area. Aortic stenosis caused an increase in HOP concentration, while the LOS group showed no difference as compared with the control group. Blockade of the renin-angiotensin system with AT1 blocker and ACEI may attenuate the development of heart hypertrophy, but only the blockade of AT1 receptors attenuates left ventricular interstitial fibrosis.