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Gastrocnemius fatigue is increased and blood flow is reduced in adult skeletal myocyte‐specific VEGF‐deficient mice
Author(s) -
Goldberg Daniel B,
Tang Kechun,
Wagner Peter D.,
Breen Ellen C.
Publication year - 2010
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.24.1_supplement.774.20
Subject(s) - endocrinology , medicine , skeletal muscle , blood flow , contraction (grammar) , hemodynamics , gastrocnemius muscle , myocyte , chemistry , anatomy , muscle contraction , myogenic contraction , biology , smooth muscle
Adult skeletal muscle‐specific VEGF gene‐deleted mice demonstrate exercise limitation, but muscle capillarity is maintained. To determine if exercise impairment is due to reduced skeletal muscle blood flow, gastrocnemius flow at rest and during electrically stimulated (ES) muscle contraction was assessed with fluorescent microspheres. Myocyte‐specific VEGF gene deletion was tamoxifen‐induced (D0‐D4, i.p.) in 4 month old VEGFLoxP X HSA‐Cre‐ERT2(+) and (−) mice. On day 21 post‐tamoxifen gastrocnemius VEGF is reduced by 94%. At this time point the gastrocnemius complex of one leg was stimulated via the sciatic nerve (10 volts) and force monitored by a pressure transducer connected to the tendon. 15 μ microspheres (0.2 ml, 1 x 10 6 beads/ml) were delivered into the aorta via the left carotid artery during the first minute of contractions. VEGFLoxP X HSA‐Cre‐ERT2(+) mice had 76% less resting gastrocnemius flow than control (Cre −). Only control mice increased blood flow during ES (by 60%). Time to reach 50% of initial force was reduced in VEGF‐deficient mice [156+/−31 (sd) sec.] compared to controls [475+/−246 (sd) sec.]. These data suggest that reduced skeletal myocyte‐specific VEGF expression in adult mice attenuates both basal and contraction‐induced blood flow, and this vascular alteration may contribute to the greater muscle fatigue.