Effect of lower limb exercise on forearm vascular function: contribution of nitric oxide.
We examined vascular function in an inactive muscle bed, the forearm, during lower limb exercise and determined the contribution of endothelium-derived nitric oxide (NO) to the hyperemic response. Eight young males were randomized to participate in two studies, each consisting of two bouts of lower limb exercise, separated by a 30-min recovery. Peak forearm blood flow (PFBF) and mean blood flow (MFBF) were continuously recorded at baseline and during exercise using continuous high-resolution vascular ultrasound and Doppler flow velocity measurement. During one session, the brachial artery was cannulated to allow continuous infusion of saline or N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthase. The alternate session was performed to control for possible effects of repeated exercise. At 60, 100, and 160 W, L-NMMA significantly decreased both PFBF and MFBF compared with the saline infusion. These results suggest that systemic production of NO occurs during exercise in resting vessel beds, which do not feed metabolically active tissue. This finding provides a plausible explanation for the antiatherogenic benefits of exercise.
Department of Human Movement and Exercise Science, The University of Western Australia, Nedlands 6907, Western Australia.
Daniel
D
Green
Craig
C
Cheetham
Louise
L
Mavaddat
Katie
K
Watts
Matthew
M
Best
Roger
R
Taylor
Gerard
G
O'Driscoll
D000293:Adolescent; D000328:Adult; D001642:Bicycling / Q000502:physiology; D001916:Brachial Artery / Q000502:physiology; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D015444:Exercise / Q000502:physiology*; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D017078:Laser-Doppler Flowmetry; D007866:Leg / Q000502:physiology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D019323:omega-N-Methylarginine / Q000008:administration & dosage
D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide