ABSTRACT
<p><b>OBJECTIVE</b>This study investigated the effects of aqueous leaf extract of Tridax procumbens (ALETP) on contractile activity of corpus cavernosum in N-nitro-l-arginine methyl ester (l-NAME)-induced hypertensive male rats.</p><p><b>METHODS</b>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 IV 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 cavernosum from each of the four groups were exposed to increasing concentrations of acetylcholine (ACh) and sodium nitroprusside (SNP) (10-10mol/L) after contraction with phenylephrine (10 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.</p><p><b>RESULTS</b>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). Cavernosa 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 cavernosa strips from the l-NAME-only treated group (P < 0.05), while ALETP co-treated groups showed enhanced percentage relaxation.</p><p><b>CONCLUSION</b>ALETP treatment of l-NAME-induced hypertensive rats promotes a relaxant effect on isolated cavernosa strips. ALETP shows potential in correcting erectile dysfunction in hypertension.</p>