Effect of ascorbic acid treatment on endothelium-dependent and neurogenic relaxation of corpus cavernosum from middle-aged non-insulin dependent diabetic rats

AIMS: The purpose of the present study was to investigate functional responses and nitric oxide synthase activity in the corpus cavernosum of young control, middle-aged control and middle-aged non-insulin dependent diabetic rats. METHODS: The animal groups were treated with ascorbic acid. RESULTS: Acetylcholine-mediated endothelium-dependent relaxation of cavernosal tissue was significantly attenuated from a maximum of 58.0 +/- 4.1% (1 mmol, n = 10) in young rats to 44.3 +/- 1.6% in aged-matched controls (P < 0.05) and to 23.3 +/- 2.8% in non-insulin-dependent diabetes mellitus rats (P < 0.01). These deficits in acetylcholine responsiveness were completely prevented by ascorbic acid treatment. Non-adrenergic non-cholinergic relaxations evoked by electrical field stimulation (0.5-64.0 Hz) in the corpus cavernosum of middle-aged control and non-insulin dependent (NID) diabetic rats are blunted and were not restored by ascorbic acid. The histochemical findings demonstrated a decrease of nicotinamide adenine dinucleotide phosphate-diaphorase staining in the cavernosal tissue obtained from middle-aged control rats and middle-aged diabetic rats. CONCLUSION: Partial correction by ascorbic acid may suggest the importance of reactive oxygen species and a therapeutic approach in impotent NID diabetic men.