title: Effect of sildenafil on platelet function and platelet cGMP of patients with erectile dysfunction.
abstract: To investigate the effect of sildenafil on platelet function and cyclic guanosine monophosphate (cGMP) levels in patients with erectile dysfunction, we evaluated the association between erectile function and platelet responses after administration of 100 mg sildenafil. Erectile responses were monitored after 8 daily doses of the drug. Adenosine diphosphate (ADP) and collagen-induced platelet aggregation and simultaneous adenosine triphosphate (ATP) release and cGMP levels were determined before and after sildenafil therapy. Basal levels for platelet aggregation, ATP release and cGMP were compared with age-matched controls. There was no difference among basal levels of platelet responses between patients and controls, except for ADP-induced platelet aggregation (P = 0.04). It was significantly higher in the patient group. Analysis of the responses to sildenafil revealed that for the patients who showed a positive erectile response, there was a significant increase in platelet cGMP (P = 0.028) and a decrease in ADP-induced platelet aggregation (P = 0.04). However, for those who showed a negative or poor erectile response, there was no change in platelet cGMP levels and platelet functions. Sildenafil did not affect collagen-induced platelet responses although cGMP levels of the responders increased. It is concluded that sildenafil increases platelet cGMP in the patients with positive erectile response. Therefore, it has been speculated that platelet cGMP may be used as an index for erectile response.
authors.affiliation: Department of Urology, School of Medicine, Selcuk University, Konya, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Akand
authors.affiliation: Department of Physiology, School of Medicine, Bülent Ecevit University, Zonguldak, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Gencer
authors.affiliation: Department of Urology, School of Medicine, Ankara University, Ankara, Turkey.
authors.forename: Ö
authors.initials: Ö
authors.lastname: Yaman
authors.affiliation: Department of Physiology, School of Medicine, Ankara University, Ankara, Turkey.
authors.forename: G
authors.initials: G
authors.lastname: Erişgen
authors.affiliation: Department of Physiology, School of Medicine, Ankara University, Ankara, Turkey.
authors.forename: D
authors.initials: D
authors.lastname: Tekin
authors.affiliation: Department of Urology, School of Medicine, Ankara University, Ankara, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Özdiler
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000737:chemistry / Q000187:drug effects*; D016022:Case-Control Studies; D006152:Cyclic GMP / Q000097:blood*; D007172:Erectile Dysfunction / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058986:Phosphodiesterase 5 Inhibitors / Q000627:therapeutic use*; D010974:Platelet Aggregation / Q000187:drug effects; D000068677:Sildenafil Citrate / Q000627:therapeutic use*
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D000068677:Sildenafil Citrate; D006152:Cyclic GMP
keywords: cGMP; erectile dysfunction; phosphodiesterase; platelet; sildenafil