ABSTRACT
<p><b>OBJECTIVE</b>To study the effects of different doses of cigarette smoke extract (CSE) on the erectile function of male rats and the mechanism of smoking-induced erectile dysfunction (ED).</p><p><b>METHODS</b>A total of 75 healthy male SD rats were randomly divided into Groups A (control), B (dimethyl sulphoxide [DMSO]), C (low-dose CSE), D (medium-dose CSE) and E (high-dose CSE). CSE models were established in male SD rats by hypodermic injection, and 60 days later observed for penile erection following subcutaneous injection of apomorphine. Then the rats were killed and the penile cavernous body obtained for the examination of NOS activity by chromatometry and the determination of Cx43 expression by laser scanning confocal fluorescence microscopy (LCSM).</p><p><b>RESULTS</b>Compared with the control and DMSO groups, penile erection frequency, NOS activity and Cx43 expression in the penile cavernous tissue were significantly decreased in the CSE groups (P < 0.05), and the decrease was proportional to the increase of the doses of CSE. No statistically significant differences were observed between the control and DMSO groups (P > 0.05).</p><p><b>CONCLUSION</b>Cigarette smoke obviously reduces NOS activity and Cx43 expression in the penile cavernous tissue and seriously affects penile erection. The higher the dose, the more serious the influence. The decreases of NOS activity and Cx43 expression may be an important mechanism of ED.</p>