title: Aging is associated with endothelial dysfunction in the human forearm vasculature.
abstract: OBJECTIVE
  Our objective was to examine the role of the endothelium in maintaining vascular tone in the basal as well as in the contracted state during aging.
  
  
  METHODS
  Responses to brachial artery infusion of acetylcholine in presence and absence of NG-nitro-L-arginine methyl ester (L-NAME) and to angiotensin II were studied in 11 young and 12 old white subjects.
  
  
  METHODS
  Strain gauge plethysmography was used to measure forearm vascular resistance (FVR). The dose of acetylcholine at 50% maximal observed decrease in forearm vascular resistance (EC50) was significantly higher (11.0 +/- 1.59 vs 7.07 +/- .65 microg/min, respectively; mean +/-SEM; P < .05) and the FVR at maximal acetylcholine effect (Emax) remained greater (12.6 +/- 1.75 vs 7.15 +/- 1.25 mm Hg/100 mL tissue volume/min; P < .02) in old compared with young subjects. Acetylcholine effect was significantly reversed by concomitant administration of L-NAME, as indicated by the increase in EC50 (old, 20.2 +/- 3.69; young, 11.9 +/- 1.68 microg/min).
  
  
  RESULTS
  There was no age-related difference in sodium nitroprusside-induced decrease in FVR. The EC50 and Emax for angiotensin II-mediated increase in FVR were 7.87 +/- 1.15 and 8.36 +/- 1.00 ng/min (EC50) and 5.30 +/- .67 vs 6.56 +/-1.25 mm Hg/100 mL tissue volume/min (Emax), and these were not different in old and young subjects, respectively.
  
  
  CONCLUSIONS
  These data indicate that aging is associated with impaired endothelial- dependent vascular relaxation and that this is selective, with no age-related change in endothelial-independent vascular relaxation or angiotensin II-mediated vascular contraction.
authors.affiliation: Department of Medicine, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: N
authors.initials: N
authors.lastname: Andrawis
authors.forename: D S
authors.initials: DS
authors.lastname: Jones
authors.forename: D R
authors.initials: DR
authors.lastname: Abernethy
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology; D001916:Brachial Artery / Q000187:drug effects / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D010991:Plethysmography; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014666:Vasomotor System / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000804:Angiotensin II; D009599:Nitroprusside; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester