Spironolactone increases myocardial performance and reduces right ventricular and atrial weights in spontaneously hypertensive rats

The purpose of this study was to evaluate the effects of spironolactone (SPR), started before clinical evidence of heart failure, on cardiac remodeling in spontaneously hypertensive rats (SHR). Methods Thirty six 13 month old SHR were divided into control and SPR (20 mg/kg/day for six months) groups. Systolic blood pressure (BP) was measured by tail‐cuff method. Echocardiogram (ECHO) was performed to evaluate in vivo cardiac structures and left ventricular (LV) function. Myocardial function was analyzed in LV papillary muscle during isometric contractions at 1.25 mM calcium concentration. Right ventricle, LV, and atria were weighed. Statistics: Student's t test and Fisher exact test. Results BP was not different between groups at the end of the experiment (control: 184±24; SPR: 197±22 mmHg; p>0.05). Mortality rate was lower in SPR group but without statistical difference (12.5% vs 25%, p>0.05). ECHO did not show differences in cardiac structures or LV systolic and diastolic function between groups. Myocardial function evaluated in vitro showed better functional performance in SPR group. Right ventricular and atrial weights were lower in SPR versus control groups. Conclusion Aldosterone blockade started before clinical evidence of heart failure shows benefitial effects on myocardial performance and right ventricular and atrial weights in spontaneously hypertensive rats. Support: FAPESP and CNPq.