Renin‐angiotensin‐aldosterone system blockade ameliorates myocardial and ventricular function of rats with diabetes mellitus

Abstract

The objective of this study was to evaluate the influence of renin‐angiotensin‐aldosterone system (RAAS) blockade with losartan (LOS) on cardiac structure and function of rats with diabetes mellitus (DM).MethodsMale Wistar rats with 300 g body weight were divided into four groups: control (CTL, n=20), CTL+LOS (n=22), diabetic (DM, n=24), and DM+LOS (n=18). DM was induced by streptozotocin; LOS was diluted in drinking water and administered for 8 weeks. Arterial pressure (AP) was measured by tail‐cuff method. Echocardiogram (Echo) was performed to evaluate in vivo cardiac structures and left ventricular (LV) function. In vitro myocardial function was analyzed in LV papillary muscle. Statistics: Variables were compared by ANOVA (p<0.05).ResultsAP was lower in DM+LOS compared to the DM group (103±15 vs 120±15 mmHg). The in vitro functional study showed better myocardial performance in DM+LOS vs. DM group (developed tension ‐ DT: 7.32±2.00 vs. 5.90±1.29 g/mm2;p<0.05). Echo showed greater LV diastolic diameter (CTL: 8.05±0.54; CTL+LOS: 8.11±0.46; DM: 8.42±0.31; DM+LOS: 8.14±0.42 mm) and left atrial (LA) diameter (LA/aorta ‐ CTL: 1.34±0.09; CTL+LOS: 1.33±0.11; DM: 1.50±0.11; DM+LOS:1.51±0.13) in DM groups, and lower LV diastolic diameter in DM+LOS vs. DM group. LV systolic (mitral annular velocity by tissue Doppler) and diastolic function (isovolumic relaxation time and tissue Doppler Em/Am ratio) was impaired in DM group and improved by LOS.ConclusionThe RAAS blockade improves myocardial and ventricular function in diabetes mellitus rats. Support: CNPq and CAPES.