Effect of sildenafil-induced nitric oxide on the histomorphology of cardiomyocytes in male rats

INTRODUCTION: Although sildenafil citrate, one of the selective phosphodiesterase-5 (PDE5) inhibitors, is considered the best treatment for erectile dysfunction, studies have shown that it has also a beneficial effect on a variety of cardiovascular conditions. In spite of reports of a significant protective effect of sildenafil against necrosis in intact hearts, there are also contradictory reports regarding its beneficial effect on the heart. Since there are not enough reports regarding the histomorphological changes in the cardiomyocytes after exposure to sildenafil citrate, the present study was conducted to observe the same along with other biochemical parameters. MATERIALS AND METHODS: Adult male albino rats of Wistar strain were used in the present study. The animals were divided into a control group and two experimental groups containing six rats each. The animals were treated with a solution of sildenafil citrate dissolved in distilled water. Histomorphological changes were observed by light microscopy and the levels of nitric oxide (NO) and PDE in the heart were measured by spectrophotometry. RESULTS: It was observed that animals treated with sildenafil citrate showed a highly significant increase in NO and a decrease in PDE level, but the histological architecture of the cardiomyocytes did not show much change other than a slightly elongated and swollen nucleus. CONCLUSIONS: This study shows that sildenafil citrate at low dosage is well tolerated by cardiac muscle cells, but as dosage increases, it may become detrimental through its NO and PDE activity.