TY - JOUR
T1 - Whole body and leg acetate kinetics at rest, during exercise and recovery in humans
AU - van Hall, G
AU - Sacchetti, M
AU - Rådegran, G
PY - 2002/7/1
Y1 - 2002/7/1
N2 - We have used a constant [1,2-(13)C]acetate infusion (0.12 micromol x min(-1) x kg( 1)) for 2 h at rest, followed by 2 h of one-legged knee-extensor exercise at 65% of leg maximal workload, and 3 h of recovery in six post-absorptive volunteers to quantify whole-body and leg acetate kinetics and determine whether the whole-body acetate correction factor can be used to correct leg substrate oxidation. The acetate whole-body rate of appearance (R(a)) was not significantly different at rest, during exercise or during recovery (365-415 micromol x min(-1)). The leg net acetate uptake was similar at rest and during recovery (approximately 10 micromol x min(-1)), but increased approximately 5-fold with exercise. At rest the leg acetate uptake (approximately 15 micromol x min(-1)) and release (approximately 5 micromol x min(-1)) accounted for 4 and 1.5 % of whole-body acetate disposal (R(d)) and R(a), respectively. When the leg acetate kinetics were extrapolated to the total body skeletal muscle mass, then skeletal muscle accounted for approximately 16 and approximately 6% of acetate R(d) and R(a). With exercise, leg acetate uptake increased approximately 6-fold, whereas leg acetate release increased 9-fold compared with rest. Whole-body acetate carbon recovery increased with time of infusion at rest and during recovery from 21% after 1.5 h of infusion to 45% in recovery after 7 h of infusion. Leg and whole-body acetate carbon recovery were similar under resting conditions, both before and after exercise. During exercise whole-body acetate carbon recovery was approximately 75%, however, acetate carbon recovery of the active leg was substantially higher (approximately 100%). It is concluded that inactive skeletal muscle plays a minor role in acetate turnover. However, active skeletal muscle enhances several-fold acetate uptake and subsequent oxidation, as well as release and its contribution to whole-body acetate turnover. Furthermore, under resting conditions the whole-body acetate correction factor can be used to correct for leg, skeletal muscle, substrate oxidation, but not during exercise.
AB - We have used a constant [1,2-(13)C]acetate infusion (0.12 micromol x min(-1) x kg( 1)) for 2 h at rest, followed by 2 h of one-legged knee-extensor exercise at 65% of leg maximal workload, and 3 h of recovery in six post-absorptive volunteers to quantify whole-body and leg acetate kinetics and determine whether the whole-body acetate correction factor can be used to correct leg substrate oxidation. The acetate whole-body rate of appearance (R(a)) was not significantly different at rest, during exercise or during recovery (365-415 micromol x min(-1)). The leg net acetate uptake was similar at rest and during recovery (approximately 10 micromol x min(-1)), but increased approximately 5-fold with exercise. At rest the leg acetate uptake (approximately 15 micromol x min(-1)) and release (approximately 5 micromol x min(-1)) accounted for 4 and 1.5 % of whole-body acetate disposal (R(d)) and R(a), respectively. When the leg acetate kinetics were extrapolated to the total body skeletal muscle mass, then skeletal muscle accounted for approximately 16 and approximately 6% of acetate R(d) and R(a). With exercise, leg acetate uptake increased approximately 6-fold, whereas leg acetate release increased 9-fold compared with rest. Whole-body acetate carbon recovery increased with time of infusion at rest and during recovery from 21% after 1.5 h of infusion to 45% in recovery after 7 h of infusion. Leg and whole-body acetate carbon recovery were similar under resting conditions, both before and after exercise. During exercise whole-body acetate carbon recovery was approximately 75%, however, acetate carbon recovery of the active leg was substantially higher (approximately 100%). It is concluded that inactive skeletal muscle plays a minor role in acetate turnover. However, active skeletal muscle enhances several-fold acetate uptake and subsequent oxidation, as well as release and its contribution to whole-body acetate turnover. Furthermore, under resting conditions the whole-body acetate correction factor can be used to correct for leg, skeletal muscle, substrate oxidation, but not during exercise.
KW - Acetates/blood
KW - Adult
KW - Algorithms
KW - Carbon Dioxide/metabolism
KW - Diet
KW - Energy Metabolism/physiology
KW - Exercise/physiology
KW - Gas Chromatography-Mass Spectrometry
KW - Humans
KW - Kinetics
KW - Leg/diagnostic imaging
KW - Male
KW - Muscle, Skeletal/diagnostic imaging
KW - Oxidation-Reduction
KW - Palmitates/metabolism
KW - Rest/physiology
KW - Ultrasonography
U2 - 10.1113/jphysiol.2001.014340
DO - 10.1113/jphysiol.2001.014340
M3 - Journal article
C2 - 12096068
SN - 0022-3751
VL - 542
SP - 263
EP - 272
JO - The Journal of physiology
JF - The Journal of physiology
IS - Pt 1
ER -