Viagra Research Today is a free monthly online journal that collates and summarizes the latest research about Viagra, including details on sildenafil, erectile dysfunction, impotence, side-effects, alternatives. | ||||||||
|
Chronic sildenafil improves erectile function and endothelium-dependent cavernosal relaxations in rats: lack of tachyphylaxis.Behr-Roussel D, Gorny D, Mevel K, Caisey S, Bernabé J, Burgess G, Wayman C, Alexandre L, Giuliano F Pelvipharm, Domaine CNRS, 1 Avenue de la terrasse, Bâtiment 5, 91190 Gif sur Yvette, France. OBJECTIVES: Sildenafil is a widely-prescribed effective on-demand treatment of erectile dysfunction (ED). Chronic treatment with sildenafil could help patients with ED. METHODS: The effects of an 8-week long treatment with sildenafil (60 mg/kg/d sc) in male Sprague Dawley rats were evaluated on electrically-elicited erectile responses in vivo before and after an acute injection of sildenafil (0.3mg/kg iv). In addition, endothelium-dependent and -independent relaxations of strips of corpus cavernosum in vitro were examined. All experiments were performed 36 hours after the last injection of sildenafil. RESULTS: Endothelium-dependent relaxations of cavernosal strips to acetylcholine were enhanced after chronic treatment with sildenafil while relaxations to A23187 or sodium nitroprusside were unchanged. Frequency-dependent erectile responses elicited by cavernous nerve stimulation were significantly improved. Moreover, the erectile responses to acute sildenafil were greater in chronically-treated rats with sildenafil. CONCLUSIONS: This is the first report providing experimental support for chronic dosing with sildenafil which could be of use for patients that are poor responders to on-demand treatment. Chronic sildenafil may regulate the transduction pathway leading to the activation of eNOS but has no effect on NO bioavailability or on the cGMP pathway, thereby eliminating a possible concern for tachyphylaxis. Published 7 December 2004 in Eur Urol, 47(1): 87-91.
© 2004-2008 Viagra Research Today. All Rights Reserved. |
| ||||||
