Journal
JOURNAL OF APPLIED PHYSIOLOGY
Volume 104, Issue 1, Pages 186-197Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.00731.2007
Keywords
exercise; blood flow; oxygen consumption; muscle; kidney
Categories
Funding
- NATIONAL CENTER FOR RESEARCH RESOURCES [R24RR018276] Funding Source: NIH RePORTER
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [P01HL052490] Funding Source: NIH RePORTER
- NCRR NIH HHS [R24 RR018276-04, R24 RR018276, RR-18276] Funding Source: Medline
- NHLBI NIH HHS [P01 HL052490, P01 HL052490-12, HL-52490] Funding Source: Medline
Ask authors/readers for more resources
Nitric oxide (NO) is potentially involved in several responses to acute exercise. We tested the hypotheses that inhibition of NO formation reduces maximal O-2 delivery to muscle, but does not affect O-2 utilization by muscle, therefore lowering maximal O-2 consumption. To test these hypotheses, swine (similar to 30 kg) drank either tap water (Con, n = 25) or water with N-G-nitro-L-arginine methyl ester (8.0 +/- 0.4 mg.kg(-1).day(-1) for >= 4 wk; LN, n = 24). Treatment efficacy was reflected by higher mean arterial pressure and lower plasma NO metabolite concentration in LN than Con (both P < 0.05). Swine completed two graded treadmill running tests to maximum. In the first test, O-2 consumption was determined at rest through maximal exercise intensity. O-2 consumption did not differ between groups at rest or at most exercise intensities, including maximum (Con, 40.8 +/- 1.8 ml.min(-1).kg(-1); LN, 40.4 +/- 2.9; not significant). In the second test, tissue-specific blood flows were determined using the radiolabeled-microsphere technique. At rest, blood flows were lower (P < 0.05) in LN compared with Con for a number of tissues, including kidney, adrenal, lung, and several skeletal muscles. During both submaximal and maximal exercise, however, blood flows were similar between Con and LN for all 16 muscles examined; only blood flows to kidney (Con, 99 +/- 16 ml.min(-1).100 g; LN, 55 +/- 15; P < 0.05) and pancreas (Con, 25 +/- 7; LN, 6 +/- 2; P < 0.05) were lower in LN at maximum. Endothelium-dependent, but not -independent, relaxation of renal arterial segments was reduced (P < 0.05) in vitro. These data indicate that exercise-induced increases in muscle blood flows are maintained with chronic inhibition of NO formation and that maximal O-2 consumption is therefore preserved. Redundant vasodilatory pathways and/or upregulation of these pathways may underlie these findings.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available