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Increased ATP delivery to contracting skeletal muscle blunts sympathetic vasoconstriction in humans (1172.5)
Author(s) -
Hearon Christopher,
Racine Matthew,
Richards Jennifer,
Luckasen Gary,
Larson Dennis,
Dinenno Frank
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1172.5
Subject(s) - vasoconstriction , vasodilation , medicine , phenylephrine , cardiology , endocrinology , sodium nitroprusside , blood pressure , nitric oxide
Sympathetic stimulation of postjunctional α‐adrenergic receptors elicits vasoconstriction in resting skeletal muscle that is blunted during exercise in an intensity dependent manner. This ‘sympatholysis’ is hypothesized to occur due to increased circulating ATP. We tested the hypothesis that infusion of a non‐sympatholytic low dose of ATP during mild exercise will evoke sympatholysis in humans. In young adults ( n =8), we measured forearm blood flow (Doppler Ultrasound) and calculated vascular conductance (FVC) to local intra‐arterial infusion of phenylephrine (PE; α 1 ‐agonist) during: 1) control vasodilator infusion (low dose adenosine triphosphate, ATP; sodium nitroprusside, SNP), 2) mild (5% maximum voluntary contraction; MVC) or moderate (15% MVC) intensity handgrip exercise, and 3) combined ATP or SNP + 5% exercise. Vasoconstriction to PE during mild exercise (ΔFVC: ‐30±1%) was similar to that observed during ATP and SNP (ΔFVC: ‐30±3 and ‐35±3%; NS), however this was blunted during moderate exercise (ΔFVC: ‐17±3%; P<0.05). ATP + 5% exercise blunted PE mediated vasoconstriction similar to that seen during moderate intensity exercise (ΔFVC: ‐18±3%). In contrast, SNP + 5% exercise did not blunt PE mediated vasoconstriction (ΔFVC: ‐34±5%). These data suggest that increasing ATP delivery to contracting muscle during exercise can blunt sympathetic vasoconstriction in humans. Grant Funding Source : Supported by: H HL102720L