RESUMO
Objective To explore the mechanisms of angiotensin Ⅱ (Ang Ⅱ) induced apoptosis of cultured cardiomyocytes of neonatal rats. Methods Cultured neonatal rat cardiomyocytes were divided into three groups. Cells in the control group were incubated in serum-free medium for 2, 6, 12, and 24 h. Cells in Ang Ⅱ group were incubated with Ang Ⅱ at the dose of 10 -7 mol/L for 2, 6, 12, and 24 h. Cells in Ang Ⅱ and Ang Ⅱ type 1 receptor antagonist group were incubated in medium containing 10 -7 mol/ L Ang Ⅱ plus 10 -5 mol/L irbesartan. The apoptotic cells were detected by TUNEL assay. The Bcl-2 protein expression was assessed by immunohistochemistry. Caspase-3 activity was measured by a fluorescent assay kit. Results The number of apoptotic cells in Ang Ⅱ group increased significantly in a time-dependent manner, accompanied by decreased Bcl-2 protein expression but increased activity of caspase-3. Treatment with irbesartan resulted in decreased number of apoptotic cells and decreased activity of caspase-3. Conclusion Angiotensin Ⅱ could induce the apoptosis of neonatal rat cardiomyocytes through the caspase-dependent pathway, which might be mediated by Ang Ⅱ type 1 receptor. Bcl-2 may participate in the regulation.