title: Androgens and penile erection: evidence for a direct relationship between free testosterone and cavernous vasodilation in men with erectile dysfunction.
abstract: OBJECTIVE
  Androgens are essential in the maintenance of nitric oxide-mediated erectile activity in the rat. The objective of the present study was to investigate the role of androgens in regulating trabecular smooth muscle relaxation in the corpus cavernosum in response to vasoactive challenge in men with erectile dysfunction (ED).
  
  
  METHODS
  Retrospective, double-blind correlation analyses.
  
  
  METHODS
  Fifty-two impotent patients without confounding risk factors for ED were obtained from a total of 250 undergoing diagnostic evaluation.
  
  
  METHODS
  All patients had dynamic colour duplex ultrasound (D-CDU) and hormonal evaluation for LH, total and free testosterone, SHBG and oestradiol.
  
  
  RESULTS
  Based upon D-CDU results patients were diagnosed as having arteriogenic (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 psychogenic (P)-ED was made by comprehensive psychogenic testing and confirmed by normal D-CDU results. AR and CVO patients had altered compliance of cavernous arteries recorded by D-CDU [20-25% lower resistive index (RI) than patients with psychogenic ED], and lower free testosterone (FT) levels than psychogenic 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 strong direct correlation between resistive index values and FT levels (r = 0.47, P = 0.002); the relationship was maintained also when adjusted for age, SHBG and oestradiol (r = 0.37, P = 0.02).
  
  
  CONCLUSIONS
  These results indicate that in men with erectile dysfunction low free testosterone may correlate independently of age with the impaired relaxation of cavernous endothelial and corporeal smooth muscle cells to a vasoactive challenge. These findings give clinical support to the experimental knowledge of the importance of androgens in regulating smooth muscle function in the penis.
authors.affiliation: Cattedra di Andrologia, Dipartimento di Fisiopatologia Medica, Università 'La Sapienza', Cattedra di Endocrinologia, Università 'Tor Vergata', Rome, Italy. amfaversa@yahoo.com
authors.forename: A
authors.initials: A
authors.lastname: Aversa
authors.forename: A M
authors.initials: AM
authors.lastname: Isidori
authors.forename: M U
authors.initials: MU
authors.lastname: De Martino
authors.forename: M
authors.initials: M
authors.lastname: Caprio
authors.forename: E
authors.initials: E
authors.lastname: Fabbrini
authors.forename: M
authors.initials: M
authors.lastname: Rocchietti-March
authors.forename: G
authors.initials: G
authors.lastname: Frajese
authors.forename: A
authors.initials: A
authors.lastname: Fabbri
mesh_terms: D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000097:blood / Q000503:physiopathology*; D004958:Estradiol / Q000097:blood; D006801:Humans; D016014:Linear Models; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D010413:Penis / Q000098:blood supply / Q000503:physiopathology; D012189:Retrospective Studies; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood / Q000502:physiology*; D018615:Ultrasonography, Doppler, Color; D014664:Vasodilation
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone