Androgens and penile erection: evidence for a direct relationship between free testosterone and cavernous vasodilation in men with erectile dysfunction
A. Aversa et al., Androgens and penile erection: evidence for a direct relationship between free testosterone and cavernous vasodilation in men with erectile dysfunction, CLIN ENDOCR, 53(4), 2000, pp. 517-522
OBJECTIVE Androgens are essential in the maintenance of nitric oxide-mediat
ed erectile activity in the rat. The objective of the present study was to
investigate the role of androgens in regulating trabecular smooth muscle re
laxation in the corpus cavernosum in response to vasoactive challenge in me
n with erectile dysfunction (ED).
DESIGN Retrospective, double-blind correlation analyses.
PATIENTS Fifty-two impotent patients without confounding risk factors for E
D were obtained from a total of 250 undergoing diagnostic evaluation.
MEASUREMENTS All patients had dynamic colour duplex ultrasound (D-CDU) and
hormonal evaluation for LH, total and free testosterone, SHBG and oestradio
l.
RESULTS Based upon D-CDU results patients were diagnosed as having arteriog
enic (AR, n = 18; mean age 51) or corporeal venocclusive (CVO, n = 13; mean
age 49) ED; in other patients (n = 21, mean age 43) a diagnosis of psychog
enic (P)-ED was made by comprehensive psychogenic testing and confirmed by
normal D-CDU results. AR and CVO patients had altered compliance of caverno
us arteries recorded by D-CDU [20-25% lower resistive index (RI) than patie
nts with psychogenic ED], and lower free testosterone (FT) levels than psyc
hogenic patients [42.3 +/- 3.5 SE and 49.3 +/- 5.2 vs. 75.2 +/- 7.6 pmol/l,
respectively; P < 0.01]. More important, in all patients there was a stron
g direct correlation between resistive index values and FT levels (r = 0.47
, P = 0.002); the relationship was maintained also when adjusted for age, S
HBG and oestradiol (r = 0.37, P = 0.02).
CONCLUSIONS These results indicate that in men with erectile dysfuntion low
free testosterone may correlate independently of age with the impaired rel
axation of cavernous endothelial and corporeal smooth muscle cells to a vas
oactive challenge. These findings give clinical support to the experimental
knowledge of the importance of androgens in regulating smooth muscle funct
ion in the penis.