OBJECTIVETo observe the effects of nicotine on endogenous carbon monoxide (CO) concentration and nitric oxide synthase (NOS) activity in the corpus cavernosum of adult male rats, and explore the possible mechanism of cigarette smoking affecting erectile dysfunction.

METHODSForty adult male rats were equally divided into three treatment groups to receive subcutaneous injection of nicotine at 0.5 mg/kg pre d for 1, 2 and 3 months, and a control group to receive saline only. After treatment, the corpus cavernosum was harvested for detection of CO concentration by modified two-wavelength spectrophotometry and NOS activity by improved Griess measurement.

RESULTSCO concentration and NOS activity were decreased by 9.05 and 13.37%, respectively, after 1 month of nicotine injection (P < 0.01), 16.47 and 22.5% after 2 months (P < 0.01), and 22.99 and 31.74% after 3 months (P < 0.01), as compared with (13.664 +/- 0.404) umol/mg prot and (9.721 +/- 0.470) U/mg prot in the control group.

CONCLUSIONNicotine can reduce endogenous CO concentration and NOS activity in the corpus cavernosum of adult male rats, which suggests the involvement of endogenous CO and NOS in the pathophysiological process of smoking-induced erectile dysfunction .