Aerobic metabolism of human quadriceps muscle: in vivo data parallel measurements on isolated mitochondria

TY - JOUR

T1 - Aerobic metabolism of human quadriceps muscle: in vivo data parallel measurements on isolated mitochondria

AU - Rasmussen, Ulla Fugmann

AU - Rasmussen, Hans N.

AU - Krustrup, Peter

AU - Quistorff, B.

AU - Saltin, Bengt

AU - Bangsbo, Jens

N1 - PUF 2001 5200 063

PY - 2001

Y1 - 2001

N2 - The aim of the present study was to examine whether parameters of isolated mitochondria could account for the in vivo maximum oxygen uptake (O2 max) of human skeletal muscle. O2 max and work performance of the quadriceps muscle of six volunteers were measured in the knee extensor model (range 10-18 mmol O2 · min1 · kg1 at work rates of 22-32 W/kg). Mitochondria were isolated from the same muscle at rest. Strong correlations were obtained between O2 max and a number of mitochondrial parameters (mitochondrial protein, cytochrome aa3, citrate synthase, and respiratory activities). The activities of citrate synthase, succinate dehydrogenase, and pyruvate dehydrogenase, measured in isolated mitochondria, corresponded to, respectively, 15, 3, and 1.1 times the rates calculated from O2 max. The respiratory chain activity also appeared sufficient. Fully coupled in vitro respiration, which is limited by the rate of ATP synthesis, could account for, at most, 60% of the O2 max. This might be due to systematic errors or to loose coupling of the mitochondrial respiration under intense exercise. skeletal muscles; maximal oxygen uptake; work rate; respiration; adenosine triphosphate synthesis

AB - The aim of the present study was to examine whether parameters of isolated mitochondria could account for the in vivo maximum oxygen uptake (O2 max) of human skeletal muscle. O2 max and work performance of the quadriceps muscle of six volunteers were measured in the knee extensor model (range 10-18 mmol O2 · min1 · kg1 at work rates of 22-32 W/kg). Mitochondria were isolated from the same muscle at rest. Strong correlations were obtained between O2 max and a number of mitochondrial parameters (mitochondrial protein, cytochrome aa3, citrate synthase, and respiratory activities). The activities of citrate synthase, succinate dehydrogenase, and pyruvate dehydrogenase, measured in isolated mitochondria, corresponded to, respectively, 15, 3, and 1.1 times the rates calculated from O2 max. The respiratory chain activity also appeared sufficient. Fully coupled in vitro respiration, which is limited by the rate of ATP synthesis, could account for, at most, 60% of the O2 max. This might be due to systematic errors or to loose coupling of the mitochondrial respiration under intense exercise. skeletal muscles; maximal oxygen uptake; work rate; respiration; adenosine triphosphate synthesis

M3 - Journal article

SN - 0193-1849

VL - 280

SP - E301-E307

JO - American Journal of Physiology - Endocrinology and Metabolism

JF - American Journal of Physiology - Endocrinology and Metabolism

IS - 2

ER -