Impairment of shear-stress-mediated vasodilation of cavernous arteries in erectile dysfunction

Penile NO release test (PNORT) has been designed to try to evaluate clinically the penile endothelial function (PEF). The shear-stress flow-mediated vasodilation (FMD) of the cavernous arteries is evaluated in two groups of patients with neurogenic (n = 23) and vasculogenic ( n = 23) erectile dysfunction (ED) by measuring their percent of increase after a 5 min occlusion of the flow. Both groups show an important FMD decrease ( 17.78 +/- 11.78 and 17.82 +/- 13%) as compared to the age-matched control group ( n = 12) ( 65.14 +/- 30.5%, P<0.001). In the vasculogenic and control groups, mean FMD is lower in patients with one or more arterial risk factors( 41 vs 67%, P = 0.025), and show a positive correlation with the plasmatic levels of bioavailable testosterone ( r = 0.37, P = 0.03) and of DHEA-S ( r = 0.46, P = 0.014). Patients achieving full erection at pharmacological test with visual sexual stimulation have a higher FMD (43.8 +/- 38%) than those who did not ( 18.52 +/- 14.37%, P = 0.008). We confirm clinically that PEF is strongly impaired in organic ED linked to neurological, vascular and endocrine factors.