title: Improvement of vascular function by acute and chronic treatment with the PDE-5 inhibitor sildenafil in experimental diabetes mellitus.
abstract: OBJECTIVE
  Diabetes-associated vascular dysfunction contributes to increased cardiovascular risk. We investigated whether the phosphodiesterase-5 inhibitor sildenafil would improve vascular function in diabetic rats.
  
  
  METHODS
  Male Wistar rats were injected with streptozotocin (50 mg kg(-1), i.v.) to induce insulin-deficient diabetes. Direct effects of sildenafil as well as modification of endothelium-dependent and -independent vasorelaxation were investigated in vitro. The effects of acute and chronic (2 week) treatment in vivo of sildenafil on vascular function were also characterized in isolated aortic segments in organ bath chambers 4 weeks after diabetes induction.
  
  
  RESULTS
  Sildenafil induced a concentration-dependent vasorelaxation, which was attenuated by the nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine. Acetylcholine-induced endothelium-dependent as well as endothelium-independent relaxation induced by the NO donor, DEA-NONOate, was significantly reduced in aortae from diabetic rats. Incubation with sildenafil in vitro normalized both endothelium-dependent and -independent relaxation in aortae from diabetic rats. Acute as well as chronic in vivo treatment with sildenafil resulted in enhanced endothelium-dependent and -independent vasorelaxation. Superoxide formation was increased in diabetes, associated with enhanced membrane expression of the NAD(P)H oxidase subunit gp91(phox) and Rac, which were both reduced by chronic treatment with sildenafil.
  
  
  CONCLUSIONS
  We demonstrate that sildenafil treatment rapidly and chronically improves vascular relaxation in diabetic rats. Treatment with sildenafil might provide a similarly beneficial effect in diabetic patients.
authors: Medizinische Klinik und Poliklinik I, Universitätsklinikum Würzburg, Julius-Maximilians-Universität Würzburg, Würzburg, Bavaria, Germany. a.schaefer@medizin.uni-wuerzburg.de
authors: A
authors: A
authors: Schäfer
authors: D
authors: D
authors: Fraccarollo
authors: S
authors: S
authors: Pförtsch
authors: U
authors: U
authors: Flierl
authors: C
authors: C
authors: Vogt
authors: J
authors: J
authors: Pfrang
authors: A
authors: A
authors: Kobsar
authors: T
authors: T
authors: Renné
authors: M
authors: M
authors: Eigenthaler
authors: G
authors: G
authors: Ertl
authors: J
authors: J
authors: Bauersachs
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004730:Endothelium, Vascular / Q000187:drug effects; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011687:Purines / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D000068677:Sildenafil Citrate; D013311:Streptozocin; D013450:Sulfones / Q000008:administration & dosage / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D013481:Superoxides; D013311:Streptozocin; D000068677:Sildenafil Citrate; D019001:Nitric Oxide Synthase; D000109:Acetylcholine