Assessment of heme oxygenase-1 (HO-1) activity in the cavernous tissues of sildenafil citrate-treated rats

Citation:
Aziz, T. A. M., F. A. M. Asmar, T. Moustafa, H. Atta, L. Rashed, D. Sabry, S. Ashour, and A. A. T. Aziz, "Assessment of heme oxygenase-1 (HO-1) activity in the cavernous tissues of sildenafil citrate-treated rats", Asian Journal of Andrology, vol. 9, issue 3, pp. 377–381, 2007.

Abstract:

Aim: To assess heme oxygenase-1 (HO-1) activity in the cavernous tissues of sildenafil citrate-treated rats.
Methods: One hudred and ninty-two Sprague-Dawley male rats, divided into four equal groups, were investigated. Group 1 the control group, received regular animal chow; group 2 received sildenafil citrate by intragastric tube; group 3 received sildenafil and HO inhibitor (zinc protoporphyrin, ZnPP); and group 4 received sildenafil and nitric oxide synthase (NOS) inhibitor L-nitroaginine methyl ester (L-NAME).Twelve rats from each group were killed after 0.5 h, 1h, 2h and 3h of drug administration. Then HO-1 activity, cGMP levels and NOS enzymatic activity and cGMP concentration increased significantly in sildenafil-treated rats compared to other groups throughout the experiment. Rats receiving either HO or NOS inhibitors showed a significant decrease in these parameters. HO-1 cavernous tissue activity and NOS enzymatic activity demonstrated a positive significant correlation with cGMP levels (r = 0.646, r = 0.612 respectively; P < 0.001).
Conclusion. The action of PDE5 inhibitor sildenafil citrate in the cavernous tissue are partly mediated through the interdependent relationship between both HO-1 and NOS activities.
Keywords. Erectile Dysfunction; heme oxygenase; sildenafil citrate; nitric oxide synthase; carbon monoxide.