[Enalaprilat in the prevention of left ventricular hypertrophy induced by isoproterenol]

To evaluate whether the enalaprilat, angiotensin I enzyme conversion inhibitor, could prevent the left ventricular hypertrophy (LVH) induced by isoproterenol.

Seventy two adult Wistar-EPM rats were divided into four groups: CON, control; ENA, treated with enalaprilat (1 mg/kg via subcutaneous (s.c.) for 8 days); ISO, treated with isoproterenol (0.3 mg via s.c. 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.

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 < or = 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.

Enalaprilat inhibited the isoproterenol action on the cardiomyocite, avoiding partially the LVH and decreasing the content of collagen fibers.