Background-Aldosterone has recently attracted considerable attention for its involvement in the pathophysiology of heart failure, in which apoptotic cell loss plays a critical role. This study examined whether aldosterone directly induces myocyte apoptosis via its specific receptors. Methods and Results-Neonatal rat cardiac myocytes were exposed to aldosterone (10 Ϫ8 to 10 Ϫ5 mol/L). Nuclear staining with Hoechst 33258 showed that aldosterone induced myocyte apoptosis in a dose-and time-dependent fashion. Treatment of myocytes with 10 Ϫ5 mol/L aldosterone significantly increased the percentage of apoptosis (15.5Ϯ1.4%) compared with serum-deprived control (7.3Ϯ0.6%). Radio ligand binding assay revealed the existence of plasma membrane receptor with high affinity (K d , 0.2 nmol/L) for aldosterone in cardiac myocytes but not in fibroblasts. Aldosterone rapidly (Ϸ30 seconds) mobilized [Ca 2ϩ ] i that was blocked by neomycin. Aldosterone induced dephosphorylation of the proapoptotic protein Bad, enhancement of mitochondrial permeability transition, decrease in mitochondrial membrane potential, and release of cytochrome c from the mitochondria into the cytosol with concomitant activation of caspase-3. These effects of aldosterone were inhibited by concurrent treatment with either an L-type Ca

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Aldosterone antagonists have been reported to prevent ventricular remodeling after myocardial infarction (MI) via their action to extracellular matrix (ECM).

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