Enalaprilat prevents the left ventricular hypertrophy induced by isoproterenol

PURPOSE: To evaluate whether the enalaprilat, angiotensin I enzyme conversion inhibitor, could prevent the left ventricular hypertrophy (LVH) induced by isoproterenol. METHODS: Seventy two adult Wistar-EPM rats were divided into four groups: CON, control; ENA, treated with enalaprilat (1mg/kg via subcutaneous (sc) for 8 days); ISO, treated with isoproterenol (0.3mg via sc for 8 days) e ENA+ISO, treated with both drugs simultaneously. Each group had the arterial blood pressure, cardiac rate and the left ventricle (LV) weight determined in 10 animals. In 8 animals from each group a small sample was taken from the LV and stained with hematoxyline-eosine and picrosirius for morphometric and ultra-structural studies with optic and transmission electronic microscopy. RESULTS: The ISO group showed that the LV weight increased 47% in comparison with control. On the other hand the ENA+ISO group showed only 22.1% increase (p<0.05). The morphometric and ultra-structural analyses revealed that isoproterenol induced cardiomyocite hypertrophy and augmented the content of the type I collagen in the cardiac interstitium. CONCLUSION: Enalaprilat inhibited the isoproterenol action on the cardiomyocite, avoiding partially the LVH and decreasing the content of collagen fibers.