TY - JOUR
T1 - Effects of training and immobilization on V̇O2 and DO2 in dog gastrocnemius muscle in situ
AU - Bebout, D. E.
AU - Hogan, M. C.
AU - Hempleman, S. C.
AU - Wagner, P. D.
PY - 1993
Y1 - 1993
N2 - To investigate the effects of exercise training and immobilization on peak O2 uptake (V̇O2) and effective O2 diffusive conductance (DO2) in skeletal muscle, three groups of purpose-bred hounds [control (C), exercise trained (E), and immobilized (I)] were studied. Group E exercised on a treadmill 1 h/day, 5 days/wk for 8 wk, while groups C and I were cage confined for 8 wk, with group I undergoing left hindlimb immobilization for the last 3 wk. Thereafter, each dog's left gastrocnemius was surgically isolated, pump perfused, and electrically stimulated to elicit peak V̇O2 in situ at three levels of arterial oxygenation. O2 delivery [(arterial O2 concentration x muscle blood flow)/100 g muscle] was kept constant among the three groups at each level of arterial oxygenation. Compared with group C, peak V̇O2/100 g muscle was 38, 33, and 19% greater and DO2/100 g muscle was 71, 75, and 68% greater during normoxia, moderate hypoxia, and severe hypoxia, respectively, in group E (P < 0.02), whereas no differences from control were found in group I. We conclude that O2 delivery is not the unique determinant of peak V̇O2 and that exercise training improves the functional blood-tissue gas exchange properties of the muscle itself. Immobilization sufficient to reduce muscle weight by 31% and citrate synthase activity by 68% has no effect on peak V̇O2/100 g muscle or DO2/100 g muscle.
AB - To investigate the effects of exercise training and immobilization on peak O2 uptake (V̇O2) and effective O2 diffusive conductance (DO2) in skeletal muscle, three groups of purpose-bred hounds [control (C), exercise trained (E), and immobilized (I)] were studied. Group E exercised on a treadmill 1 h/day, 5 days/wk for 8 wk, while groups C and I were cage confined for 8 wk, with group I undergoing left hindlimb immobilization for the last 3 wk. Thereafter, each dog's left gastrocnemius was surgically isolated, pump perfused, and electrically stimulated to elicit peak V̇O2 in situ at three levels of arterial oxygenation. O2 delivery [(arterial O2 concentration x muscle blood flow)/100 g muscle] was kept constant among the three groups at each level of arterial oxygenation. Compared with group C, peak V̇O2/100 g muscle was 38, 33, and 19% greater and DO2/100 g muscle was 71, 75, and 68% greater during normoxia, moderate hypoxia, and severe hypoxia, respectively, in group E (P < 0.02), whereas no differences from control were found in group I. We conclude that O2 delivery is not the unique determinant of peak V̇O2 and that exercise training improves the functional blood-tissue gas exchange properties of the muscle itself. Immobilization sufficient to reduce muscle weight by 31% and citrate synthase activity by 68% has no effect on peak V̇O2/100 g muscle or DO2/100 g muscle.
KW - endurance training
KW - hypoxia
KW - muscle atrophy
KW - muscle diffusing capacity
KW - oxygen diffusing capacity
KW - oxygen diffusion
KW - oxygen extraction
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U2 - 10.1152/jappl.1993.74.4.1697
DO - 10.1152/jappl.1993.74.4.1697
M3 - Article
C2 - 8514685
AN - SCOPUS:0027266797
SN - 8750-7587
VL - 74
SP - 1697
EP - 1703
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 4
ER -