title: Sildenafil reduces insulin-resistance in human endothelial cells.
abstract: BACKGROUND
  The efficacy of Phosphodiesterase 5 (PDE5) inhibitors to re-establish endothelial function is reduced in diabetic patients. Recent evidences suggest that therapy with PDE5 inhibitors, i.e. sildenafil, may increase the expression of nitric oxide synthase (NOS) proteins in the heart and cardiomyocytes. In this study we analyzed the effect of sildenafil on endothelial cells in insulin resistance conditions in vitro.
  
  
  RESULTS
  Human umbilical vein endothelial cells (HUVECs) were treated with insulin in presence of glucose 30 mM (HG) and glucosamine 10 mM (Gluc-N) with or without sildenafil. Insulin increased the expression of PDE5 and eNOS mRNA assayed by Real time-PCR. Cytofluorimetric analysis showed that sildenafil significantly increased NO production in basal condition. This effect was partially inhibited by the PI3K inhibitor LY 294002 and completely inhibited by the NOS inhibitor L-NAME. Akt-1 and eNOS activation was reduced in conditions mimicking insulin resistance and completely restored by sildenafil treatment. Conversely sildenafil treatment can counteract this noxious effect by increasing NO production through eNOS activation and reducing oxidative stress induced by hyperglycaemia and glucosamine.
  
  
  CONCLUSIONS
  These data indicate that sildenafil might improve NOS activity of endothelial cells in insulin resistance conditions and suggest the potential therapeutic use of sildenafil for improving vascular function in diabetic patients.
authors.affiliation: Centre for Clinical and Basic Research, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Mammi
authors.forename: Donatella
authors.initials: D
authors.lastname: Pastore
authors.forename: Marco F
authors.initials: MF
authors.lastname: Lombardo
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferrelli
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Caprio
authors.forename: Claudia
authors.initials: C
authors.lastname: Consoli
authors.forename: Manfredi
authors.initials: M
authors.lastname: Tesauro
authors.forename: Lucia
authors.initials: L
authors.lastname: Gatta
authors.forename: Massimo
authors.initials: M
authors.lastname: Fini
authors.forename: Massimo
authors.initials: M
authors.lastname: Federici
authors.forename: Paolo
authors.initials: P
authors.lastname: Sbraccia
authors.forename: Giulia
authors.initials: G
authors.lastname: Donadel
authors.forename: Alfonso
authors.initials: A
authors.lastname: Bellia
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Rosano
authors.forename: Andrea
authors.initials: A
authors.lastname: Fabbri
authors.forename: Davide
authors.initials: D
authors.lastname: Lauro
mesh_terms: D002478:Cells, Cultured; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000235:genetics; D042783:Endothelial Cells / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D052250:Nitric Oxide Synthase Type III / Q000235:genetics; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*; D014665:Vasodilator Agents
chemical_list: D007328:Insulin; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D012333:RNA, Messenger; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5