Impaired endothelium-dependent and neurogenic relaxation of corpus cavernosum from diabetic rats: improvement with L-arginine

Abstract

This study describes the relaxant response to acetylcholine, electrical field stimulation and sodium nitroprusside after contraction by phenylephrine (10⁻⁵ M) in corpus cavernosum from control and diabetic rats. The response to acetylcholine (10⁻⁹–10⁻³ M) and electrical field stimulation (0.5–64 Hz) is decreased and can be restored by the addition of nitric oxide synthatase substrate, l-arginine(10⁻⁵ M). The response to sodium nitroprusside is not changed in diabetic rats compared to control rats. NADPH-diaphorase staining was enhanced in a diabetic preparation compared to control preparations. The findings suggest a role for the depletion of l-arginine in diabetes mellitus. The enhanced NADPH-diaphorase staining may be due to a deficiency of NOS substrate l-arginine in the endothelium and nerves of diabetic tissues.