Penile blood cyclic guanosin monophosphate level is associated with penile Doppler ultrasound findings

Abstract

The aim of this study was to look into a molecule in penile blood sample that shows correlation with the tumescence grade and/or penile Doppler ultrasound findings. Patients admitted to urology outpatient clinic with the complaint of erectile dysfunction between November 2006 and April 2007 were evaluated. Patients with the history of phosphodiesterase inhibitor usage or genital trauma, genital abnormalities, Peyronie's disease, endocrinopathies, cardiovascular diseases and major psychiatric or neurological disorders were excluded. Those patients were later evaluated with a penile Doppler ultrasound, 10-20 min after intracavernosal injection of 60 mg of papaverine hydrochloride. Tumescence grade, peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) were recorded. Blood samples were drawn from penis and the levels of calcium, myeloperoxidase, malondialdehyde, nitrite, nitrate, vasoactive intestinal peptide and cyclic guanosin monophosphate (cGMP) and the activity of superoxide dismutase were measured. A total of 46 patients with erectile dysfunction were included. The median age of the patients was 49.3+/-10.2 (range 24-67). We could not find any significant correlation between penile Doppler ultrasound parameters and any of penile blood measurements except cGMP that demonstrated a significant negative correlation with PSV (rho=-0.533, P=0.001) and RI (rho=-0.468, P=0.005). However, a positive correlation between cGMP and EDV was detected (rho=0.322, P=0.059). Mean cGMP levels were 3.347+/-0.694 pmol ml(-1) (2.295-4.685), 3.193+/-0.669 pmol ml(-1) (2.165-4.094) and 2.742+/-0.690 pmol ml(-1) (1.290-4.011) in grades 2, 3 and 4 tumescence groups, respectively, and the difference among mean cGMP levels of these groups were statistically significant (P=0.027). As a conclusion, penile blood cGMP level showed a significant negative correlation with mean PSV, RI values and tumescence grade, whereas there was a positive but insignificant correlation between cGMP and mean EDV value.