Objective:This study investigated the effects of aqueous leaf extract ofTridax procumbens (ALETP) on contractile activity of corpus cavosum in N-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive male rats.Methods:Twenty normal,adult male rats (130-150 g) were divided into four groups of five rats each.Group Ⅰ (control) was given normal saline (0.6 mL/kg) and group Ⅱ was given L-NAME (40 mg/kg) for 6 weeks.Groups Ⅲ and ⅣV also received L-NAME (40 mg/kg) for 6 weeks but were further co-treated with 100 and 200 mg/kg of ALETP,respectively,from week 4 to week 6.All treatments were given orally.Strips of corpus cavosum from each of the four groups were exposed to increasing concentrations of acetylcholine (ACh) and sodium nitroprusside (SNP) (10-9-10 s mol/L) after contraction with phenylephrine (10-7 mol/L) to test for a dose-response effect.Response to potassium and calcium was also measured after cumulatively adding potassium and calcium (10-50 mmol/L) to potassium-and calcium-free organ chamber.Isometric contractions were recorded through an Ugo Basile data capsule acquisition system.Results:Mean arterial blood pressure was significantly reduced in the ALETP co-treated group compared to the control and L-NAME-only groups (P ＜ 0.05).Cavosa strips from ALETP co-treated rats exhibited significant inhibition of contraction in response to phenylephrine,potassium chloride,and calcium chloride (P ＜ 0.05).Relaxation in response to Ach and SNP was also significantly impaired in cavosa strips from the L-NAME-only treated group (P ＜ 0.05),while ALETP co-treated groups showed enhanced percentage relaxation.Conclusion:ALETP treatment of L-NAME-induced hypertensive rats promotes a relaxant effect on isolated cavosa strips.ALETP shows potential in correcting erectile dysfunction in hypertension.