Effects of low-dose spironolactone combined with irbesartan on cardiac hypertrophy induced by pressure overload in rats.

BACKGROUND

The mineralocorticoid receptor (MR) blockade in the heart is an attractive therapeutic option for the treatment of heart failure. However, the use of MR antagonist is limited by an increased incidence of hyperkalemia owing to MR blockade in the kidney. This study was designed to evaluate and compare the effectiveness of a low, non-pressure-lowering dose of spironolactone (Sp) with that of a conventional blood pressure-lowering dose combined with irbesartan on pathological cardiac remodeling as well as serum potassium level in pressure-overload rats.

METHODS

The pressure-overloaded myocardial remodelling was produced by partial abdominal aortic constriction (PAAC) in rats. Four weeks after PAAC, animals were respectively treated with vehicle, irbesartan (15 mg/kg) alone, low-dose Sp (1 mg/kg) or conventional-dose of Sp (20 mg/kg) in combination with irbesartan for consecutive four weeks.

RESULTS

The result demonstrated that compared to irbesartan monotherapy, the combination of irbesartan and spironolactone both in low- and conventional-dose exhibited additional cardioprotection against PAAC-induced cardiac remodelling. Low-dose spironolactone was as effective in inhibiting cardiac hypertrophy, fibrosis and in improving diastolic function as high dose. Low-dose spironolactone did not lead to a rise in potassium serum levels, but high dose did.

CONCLUSIONS

This study suggests that combined low dose of spironolactone and irbesartan may be an effective and safety therapeutic strategy for cardiac hypertrophy and heart failure.