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Contribution of muscle afferent activation to the anterior cerebral artery blood velocity response to calf exercise in humans
Author(s) -
Vianna Lauro C,
Fisher James P
Publication year - 2009
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.23.1_supplement.787.10
Subject(s) - medicine , contraction (grammar) , cerebral blood flow , skeletal muscle , blood flow , cardiology , muscle contraction , anatomy , endocrinology , chemistry
It has been proposed that the activation of mechanically sensitive muscle afferents (muscle mechanoreflex) is important for exercise‐induced increases in regional cerebral blood flow. To examine this possibility, and to assess how regional cerebral blood flow is influenced by activation of metabolically sensitive muscle afferents (muscle metaboreflex) and central signals arising from higher centers (central command), 12 subjects performed voluntary (Vol Ex) and electrically stimulated (Stim Ex) rhythmic calf exercise at 35% of maximum voluntary contraction, followed by post exercise muscle ischemia (PEMI). Anterior cerebral artery blood velocity (ACA V mean ), mean arterial pressure (MAP), and end‐tidal PCO 2 were measured throughout. Exercise induced increases in MAP were similar during Vol Ex (Δ6±2 mmHg) and Stim Ex (Δ7±2 mmHg; P>0.05). ACA V mean was increased from rest during Vol Ex (Δ15±1%; P<0.05), but remained unchanged during Stim Ex (P>0.05). MAP remained elevated during PEMI following both Vol Ex and Stim Ex (P<0.05 vs. rest), while ACA V mean was not different from rest (P>0.05). End‐tidal PCO 2 was unchanged from rest throughout. These data suggest that selective activation of skeletal muscle afferents (i.e. Stim Ex or PEMI) does not increase ACA V mean , and that increases in ACA V mean during volitional contraction of an exercising calf muscle are dependent upon the presence of central command.