title: Low nitric oxide bioavailability is associated with better responses to sildenafil in patients with erectile dysfunction.
abstract: Erectile dysfunction (ED) is a multifactorial disease associated with vascular dysfunction, low nitric oxide (NO) bioavailability, and oxidative stress. However, it is not known whether low NO bioavailability and oxidative stress affect the responsiveness of ED patients to sildenafil. We tested this hypothesis by studying 28 healthy subjects (control group), 26 patients with ED without comorbidities (ED group), and 18 patients with ED and diabetes mellitus (ED/DM group). The International Index for Erectile Function (IIEF) questionnaire was used to assess the erectile function of all participants, and their responsiveness to sildenafil was assessed as the percentage of change in the five-item version of IIEF score before and after sildenafil treatment. Levels of whole blood nitrite, antioxidants markers (ferric reducing ability of plasma (FRAP) and reduced glutathione), and oxidative stress markers (thiobarbituric acid reactive substance and protein carbonyl) were determined. We found a negative correlation between whole blood nitrite levels and the responses to sildenafil in both ED groups (P<0.05). FRAP correlated negatively with the responses to sildenafil in the ED/DM group (P<0.05). No other significant associations were found. Our findings show evidence that low NO bioavailability is associated with better responses to sildenafil in patients with ED (with or without DM).
authors.affiliation: Department of Pharmacology, State University of Campinas, Campinas, Sao Paulo, Brazil.
authors.forename: Jaqueline J
authors.initials: JJ
authors.lastname: Muniz
authors.forename: Riccardo
authors.initials: R
authors.lastname: Lacchini
authors.forename: Jonas T C
authors.initials: JT
authors.lastname: Sertório
authors.forename: Alceu A
authors.initials: AA
authors.lastname: Jordão
authors.forename: Yuri T D A
authors.initials: YT
authors.lastname: Nobre
authors.forename: Silvio
authors.initials: S
authors.lastname: Tucci
authors.forename: Antônio C P
authors.initials: AC
authors.lastname: Martins
authors.forename: Jose E
authors.initials: JE
authors.lastname: Tanus-Santos
mesh_terms: D000328:Adult; D000368:Aged; D001682:Biological Availability; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000378:metabolism; D007172:Erectile Dysfunction / Q000188:drug therapy / Q000378:metabolism*; D005978:Glutathione / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000097:blood*; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D010879:Piperazines / Q000494:pharmacology* / Q000627:therapeutic use; D050050:Protein Carbonylation; D011687:Purines / Q000494:pharmacology / Q000627:therapeutic use; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology* / Q000627:therapeutic use; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D016896:Treatment Outcome
chemical_list: D009573:Nitrites; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D017392:Thiobarbituric Acid Reactive Substances; D009569:Nitric Oxide; D000068677:Sildenafil Citrate; D005978:Glutathione