Decreased arteriolar sensitivity to shear stress in adult rats is reversed by chronic exercise activity.
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.
Sun
Dong
D
Department of Physiology, New York Medical College, Valhalla, NY 10595, USA. Dong_Sun@nymc.edu
Huang
An
A
Koller
Akos
A
Kaley
Gabor
G
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
D009599:Nitroprusside; D000109:Acetylcholine