ABSTRACT
<p><b>OBJECTIVE</b>To validate the hypothesis that the phenotypic transformation occurs in the smooth muscle cells in the corpus cavernosum of hypertensive rat and explore its impact on the erectile function of rats.</p><p><b>METHODS</b>Eighteen 16-week-old male spontaneously hypertensive rats (SHR) and 10 syngeneic normotensive rats (WKY) were used in this experiment. After measurement of systolic blood pressure of the caudal artery and examination of the erectile function with subcutaneous injection of apomorphine (APO), the rats were divided into 3 groups, namely hypertensive with erectile dysfunction (HBP-ED) group (n=6), hypertensive (HBP) group (n=12) and control group (n=10). Immunohistochemical staining and color image analysis system were used to observe expression of calponin 1 and osteopontin (OPN) in rat corpus cavernosum. Real-time quantitative RT-PCR was used to determine the expression of calponin 1 and OPN mRNAs in different groups.</p><p><b>RESULTS</b>The expressions of calponin 1 protein and mRNA were the highest in the control group and the lowest in HBP-ED group, while the expressions of OPN protein and mRNA were the highest in HBP-ED group and the lowest in the control group.</p><p><b>CONCLUSION</b>The smooth muscle cells may transform from the contractile phenotype into synthetic phenotype in the corpus cavernosum of the hypertensive rats, resulting ultimately in erectile dysfunction.</p>