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This Article Full Text Full Text (PDF) All Versions of this Article: 293/3/H1466    most recent 00273.2007v3 00273.2007v2 00273.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sugawara, J. Articles by Tanaka, H. Search for Related Content PubMed PubMed Citation Articles by Sugawara, J. Articles by Tanaka, H.

Systemic -adrenergic and nitric oxide inhibition on basal limb blood flow: effects of endurance training in middle-aged and older adults

¹Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan; ²Cardiovascular Aging Research Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas; and ³Center for Advanced Research Alliance and ⁴Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan

Submitted 5 March 2007 ; accepted in final form 11 May 2007

Endurance training improves endothelium-dependent vasodilation, yet it does not increase basal blood flow in the legs. We determined the effects of a 3-mo aerobic exercise intervention on basal leg blood flow and -adrenergic vasoconstriction and nitric oxide (NO) release in seven apparently healthy middle-aged and older adults (60 ± 3 yr). Basal femoral artery blood flow (via Doppler ultrasound) (pretraining: 354 ± 29; posttraining: 335 ± 34 ml/min) and vascular conductance did not change significantly with the exercise training. Before the exercise intervention, femoral artery blood flow increased 32 ± 16% with systemic -adrenergic blockade (with phentolamine) (P < 0.05), and the addition of nitric oxide synthase (NOS) inhibition using N^G-monomethyl-L-arginine (L-NMMA) did not affect femoral artery blood flow. After training was completed, femoral artery blood flow increased 47 ± 7% with -adrenergic blockade (P < 0.01) and then decreased 18 ± 7% with the subsequent administration of L-NMMA (P < 0.05). Leg vascular conductance showed a greater -adrenergic blockade-induced vasodilation (+1.7 ± 0.5 to +3.0 ± 0.5 units, P < 0.05) as well as NOS inhibition-induced vasoconstriction (–0.8 ± 0.4 to –2.7 ± 0.7 units, P < 0.05) after the exercise intervention. Resting plasma norepinephrine concentration significantly increased after the training. These results suggest that regular aerobic exercise training enhances NO bioavailability in middle-aged and older adults and that basal limb blood flow does not change with exercise training because of the contrasting influences of sympathetic nervous system activity and endothelium-derived vasodilation on the vasculature.

perfusion; vascular tone; endothelium; sympathetic nervous system