title: Decreased arteriolar sensitivity to shear stress in adult rats is reversed by chronic exercise activity.
abstract: OBJECTIVE
  We tested the hypothesis that the decline in endothelium-dependent arteriolar dilation in adult rats is reversed by chronic exercise activity.
  
  
  METHODS
  Rats were divided into young (8-10 weeks)-sedentary (SED(Y)), adult (29-32 weeks)-sedentary (SED(A)), and adult-exercised (EX(A), treadmill exercise for 18-20 weeks) groups. Responses of isolated arterioles ( approximately 50 microm at 80 mm Hg) of gracilis muscle were assessed to increases in perfusate flow and vasoactive agents.
  
  
  RESULTS
  With no differences in basal tone, maximal flow-induced dilations were not different between arterioles of SED(Y) and SED(A) rats (71 +/- 2 and 72 +/- 2% of passive diameter, respectively), yet the sensitivity of arterioles to shear stress (WSS(50)) was significantly less in SED(A) than in SED(Y) rats (35 +/- 4 vs. 23 +/- 3 dyne/cm(2), respectively). In vessels of EX(A) rats, maximal flow-induced dilation was significantly augmented (88 +/- 2% of passive diameter) and WSS(50) (15 +/- 1 dyn/cm(2)) was significantly reduced. Dilation to acetylcholine was enhanced in arterioles of EX(A), whereas dilation to sodium nitroprusside was not different in vessels of the three groups.
  
  
  CONCLUSIONS
  Chronic exercise activity reverses age related reduction in sensitivity of arterioles to increases in wall shear stress.
authors.affiliation: Department of Physiology, New York Medical College, Valhalla, NY 10595, USA. Dong_Sun@nymc.edu
authors.forename: Dong
authors.initials: D
authors.lastname: Sun
authors.forename: An
authors.initials: A
authors.lastname: Huang
authors.forename: Akos
authors.initials: A
authors.lastname: Koller
authors.forename: Gabor
authors.initials: G
authors.lastname: Kaley
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D001696:Biomechanical Phenomena; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply; D009599:Nitroprusside / Q000494:pharmacology; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D009599:Nitroprusside; D000109:Acetylcholine