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MacLean DA, Sinoway LI, Leuenberger U. Systemic
hypoxia elevates skeletal muscle interstitial adenosine levels in humans. Circul. 1998;Nov10;98(19):1990-1992.
Section of Cardiology, The Milton S. Hershey Medical Center,
Pennsylvania State University, Hershey, PA.
BACKGROUND: Adenosine is a potent vasodilator that has been shown to
increase in cardiac tissue in response to hypoxia. However, peripheral
vasodilatation also occurs during hypoxia, and the vasoactive substance(s)
responsible for skeletal muscle vasodilation have not yet been completely
identified. Therefore, the purpose of this study was to measure and quantify
skeletal muscle interstitial adenosine during acute systemic hypoxia.
METHODS AND RESULTS: Skeletal muscle interstitial adenosine concentrations
were determined by the microdialysis technique, in which 4 semipermeable
microdialysis probes were inserted into the vastus lateralis muscle of
6 healthy male subjects and perfused at a rate of 5 microL/min with Ringer's
solution. Sixty minutes after the insertion of the microdialysis probes,
systemic hypoxia was induced for 30 minutes by having the subjects breathe
a mixture of 10.5% O2 in N2. Arterial oxygen saturation (fingertip oximeter)
was lowered (P<0.05) from 96+/-0.7% to 74.9+/-1.4%, and forearm blood
flow was increased 28%. During normoxia, the interstitial adenosine concentration
was 0. 44+/-0.08 micromol/L, and it was increased to 1.03+/-0.15 (P<0.05)
and 0.85+/-0.09 (P<0.05) after 15 and 30 minutes of hypoxia, respectively.
CONCLUSIONS: These data are consistent with the concept that during acute
systemic hypoxia, interstitial adenosine plays a key role in stimulating
peripheral vasodilation.
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Abstracts