Characterization of corpus cavernosum smooth muscle cell phenotype in diabetic rats with erectile dysfunction

Phenotypic modulation from a contractile to a proliferative state within vascular smooth muscle cells has a critical role in the pathogenesis of a variety of cardiovascular diseases. To investigate the characterization of corpus cavernosum smooth muscle cell phenotype in diabetic rats with erectile dysfunction, a group of Sprague-Dawley rats (n=30) were induced by intraperitoneal injection of streptozotocin (60 mg kg(-1)) and screened by subcutaneous injection of apomorphine (100 μg kg(-1)) for the measurement and comparison of the penile erections, and then three different groups were defined. Primary corpus cavernosum smooth muscle cells were cultured and passaged. The cavernous tissue segments were subjected to quantitative real-time polymerase chain reaction to determine the expressions of smooth muscle α-actin (SMA), SM myosin heavy chain (SMMHC), smoothelin, calponin and myocardin. Cell contractility in vitro and western blot analysis of SMA and SMMHC in the cavernous tissues and cells were determined. Compared with the control group (n=8) and the diabetes mellitus group (n=5), the expressions of SMA, calponin, SMMHC, smoothelin and myocardin mRNA were decreased in the cavernous tissues in rats of the diabetic erectile dysfunction group (n=15; P=0.001 and 0.02, P=0.014 and 0.012, both P<0.001, P=0.005 and <0.001, P=0.003 and 0.035, respectively). The levels of SMA and SMMHC proteins showed a significant decrease in cavernous tissues and cultured cells in rats of the diabetic erectile dysfunction group. Cells of the diabetic erectile dysfunction group exhibited significantly less contractility compared with those of other groups (P<0.001). Corpus cavernosum SM cell possesses the ability to modulate the phenotype under hyperglycemic conditions, which could have a key role in the pathogenesis of diabetic erectile dysfunction.