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Estimation of skeletal muscle interstitial adenosine during forearm dynamic exercise in humansIt has been proposed that adenosine is a metabolic signal that triggers activation of muscle afferents involved in the exercise pressor reflex. Furthermore, exogenous adenosine induces sympathetic activation that mimics the exercise pressor reflex, and blockade of adenosine receptors inhibits sympathetic activation induced by exercise. Thus, we hypothesize that adenosine is released locally by the muscle during exercise. We used microdialysis probes, placed in the flexor digitorium superficialis muscle, to estimate muscle interstitial adenosine levels in humans. We estimated resting in vivo muscle interstitial adenosine concentrations (0.292+/-0.058 micromol/L, n=4) by perfusing increasing concentrations of adenosine to determine the gradient produced in the dialysate. Muscle interstitial adenosine concentrations increased from 0.23+/-0.04 to 0.82+/-0.14 micromol/L (n=14, P<0.001) during intermittent dynamic exercise at 50% of maximal voluntary contraction. Lactate increased from 0.8+/-0.1 to 2.3+/-0.3 mmol/L (P<0.001). Lower intensity (15% maximal voluntary contraction) intermittent dynamic exercise increased adenosine concentrations from 0.104+/-0.02 to 0.42+/-0.16 micromol/L (n=7). The addition of ischemia to this low level of exercise produced a greater increase in adenosine (from 0.095+/-0.02 to 0.48+/-0.2 micromol/L) compared with nonischemic exercise (0. 095+/-0.02 to 0.25+/-0.12 micromol/L). These results indicate that microdialysis is useful in estimating adenosine concentrations and in reflecting changes in muscle interstitial adenosine during dynamic exercise in humans.
Document ID
20040141563
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Costa, F.
(Vanderbilt University Nashville, TN 37212-8210, United States)
Heusinkveld, J.
Ballog, R.
Davis, S.
Biaggioni, I.
Date Acquired
August 22, 2013
Publication Date
May 1, 2000
Publication Information
Publication: Hypertension
Volume: 35
Issue: 5
ISSN: 0194-911X
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: RR-00095
CONTRACT_GRANT: HL-56693
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Program Biomedical Research and Countermeasures
NASA Discipline Regulatory Physiology

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