title: Vasodilatory action of loop diuretics: a plethysmography study of endothelial function in forearm arteries and dorsal hand veins in hypertensive patients and controls.
abstract: BACKGROUND
  Intravenous administration of loop diuretics induces venodilation before the diuretic response. We investigated whether furosemide and torasemide exert a dilatory effect on arteries and veins mediated by endothelial release of nitric oxide.
  
  
  METHODS
  We performed intermittent venous occlusion plethysmography to study forearm blood flow and dorsal hand-vein distension in response to furosemide and torasemide infusion in hypertensive patients and healthy controls.
  
  
  RESULTS
  Furosemide increased venodilation from 0.56 +/- 0.09 to 0.88 +/- 0.06 (P=0.000) in control subjects and from 0.49 +/- 0.10 to 0.75 +/- 0.12 (P=0.000) in hypertensive patients. Torasemide increased venodilation from 0.46 +/- 0.06 to 0.70 +/- 0.11 (P=0.007) in control subjects and from 0.48 +/- 0.09 to 0.67 +/- 0.12 (P = 0.03) in hypertensive patients. Co-infusion of the Nitric Oxide Synthase Inhibitor (L-NMMA)-blocked this venodilation, and the action was reversed with L-arginine. There were no significant changes in the arterial bed.
  
  
  CONCLUSIONS
  Furosemide and torasemide induce a similar dose-response curve venodilation, but they have no effect on the arterial bed. Hypertensive patients show a smaller venous endothelium-dependent response than healthy controls. The venodilation induced by both diuretics requires release of nitric oxide.
authors.affiliation: Department of Cardiology, Endothelial Function Unit, Marqués de Valdecilla University Hospital, and the Cantabria Health Service, University of Cantabria, Santander, Spain. carbfj@humv.es
authors.forename: José R
authors.initials: JR
authors.lastname: de Berrazueta
authors.forename: Josefina Perez
authors.initials: JP
authors.lastname: González
authors.forename: Inmaculada
authors.initials: I
authors.lastname: de Mier
authors.forename: Jose J
authors.initials: JJ
authors.lastname: Poveda
authors.forename: María-Teresa
authors.initials: MT
authors.lastname: García-Unzueta
mesh_terms: D000328:Adult; D001158:Arteries / Q000187:drug effects; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005542:Forearm / Q000098:blood supply*; D005665:Furosemide / Q000494:pharmacology; D006225:Hand / Q000098:blood supply*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D010991:Plethysmography; D012039:Regional Blood Flow / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D000077786:Torsemide; D014665:Vasodilator Agents; D014680:Veins / Q000187:drug effects
chemical_list: D004232:Diuretics; D013449:Sulfonamides; D014665:Vasodilator Agents; D009569:Nitric Oxide; D005665:Furosemide; D052250:Nitric Oxide Synthase Type III; D000077786:Torsemide