title: Propofol-induced relaxation of rat aorta is altered by aging.
abstract: BACKGROUND
  Propofol causes vasodilation via endothelium-dependent and -independent mechanisms. Because endothelial function is impaired with aging, the effects of propofol on endothelium-dependent vasodilation might be altered by aging. The aim of this study was thus to determine the effects of aging on vascular responses to propofol.
  
  
  METHODS
  Young (4-6 weeks old) or adult (16-25 weeks old) rats were anesthetized with sevoflurane. The thoracic aorta was dissected and cut into pieces 3-4 mm in length. In some rings, the endothelium was deliberately removed. The ring segment of the aorta was mounted for isometric force recording at a resting tension of 0.5-1.0 g in a 2 ml organ bath, containing Krebs-Ringer bicarbonate buffer. Arteries were precontracted with phenylephrine, and the function of endothelium was confirmed with acetylcholine. Then, we studied the concentration-dependent effects of propofol in endothelium-intact (control group) and -denuded aortic rings (denuded group), as well as those treated with N(ω)-nitro-L-arginine methylester (L-NAME group).
  
  
  RESULTS
  Relaxation due to propofol was observed in the control groups of both young and adult rats in a concentration-dependent manner, but the magnitude of relaxation was significantly greater in young rats. In addition, in young rats, relaxation due to propofol was significantly and equally reduced in both L-NAME and denuded groups at all propofol concentrations that we studied (10(-6)-10(-3) M). In adult rats, relaxation due to propofol was quite similar between control and L-NAME groups at all propofol concentrations, whereas it was significantly reduced in the denuded group.
  
  
  CONCLUSIONS
  These results suggest that endothelium-derived nitric oxide plays an important role in propofol-induced vasodilation in young rats, but not in adult rats.
authors.affiliation: Department of Anesthesiology, Tokushima University Hospital.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Sakai
authors.forename: Shinji
authors.initials: S
authors.lastname: Kawahito
authors.forename: Kazumi
authors.initials: K
authors.lastname: Takaishi
authors.forename: Naoji
authors.initials: N
authors.lastname: Mita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kinoshita
authors.forename: Noboru
authors.initials: N
authors.lastname: Hatakeyama
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Azma
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakaya
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitahata
mesh_terms: D000375:Aging / Q000502:physiology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology; D015742:Propofol / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D018686:Anesthetics, Intravenous; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester; D015742:Propofol