TY - JOUR

T1 - Lactate/H+ transport kinetics in rat skeletal muscle related to fibre type and changes in transport capacity

AU - Juel, null

AU - Pilegaard, null

PY - 1998

Y1 - 1998

N2 - Lactate/H+ transport kinetics were determined by means of the pH-sensitive probe BCECF in sarcolemmal giant vesicles, obtained from rat skeletal muscle, and related to variations in lactate/H+ transport capacity. Vesicle preparations were made from red and white muscles, mixed muscles, denervated muscles, muscles of old rats and rats that had been subjected to high-intensity training, endurance training, repeated exposure to hypoxia, and hypothyroid or hyperthyroid treatments. The lactate/H+ transport capacity of red muscles was greater than that of white muscles, and this difference was associated with a higher maximal transport rate (Vmax) in red muscles, whereas the Km was similar in the two muscle types. High-intensity training and hyperthyroidism increased the lactate/H+ transport capacity by enhancing Vmax without affecting Km. Similarly, a reduced transport capacity with old age and hypothyroidism was due to a decrease in Vmax. The denervation-induced decline in lactate/H+ transport capacity resulted from both an increased Km and a reduced Vmax. The present data show that muscle type differences and most changes in the lactate/H+ transport capacity are mediated by modifications in Vmax, which is expected to represent the number of membrane transporter molecules. Km is unaffected by most treatments and appears to be independent of fibre type.

AB - Lactate/H+ transport kinetics were determined by means of the pH-sensitive probe BCECF in sarcolemmal giant vesicles, obtained from rat skeletal muscle, and related to variations in lactate/H+ transport capacity. Vesicle preparations were made from red and white muscles, mixed muscles, denervated muscles, muscles of old rats and rats that had been subjected to high-intensity training, endurance training, repeated exposure to hypoxia, and hypothyroid or hyperthyroid treatments. The lactate/H+ transport capacity of red muscles was greater than that of white muscles, and this difference was associated with a higher maximal transport rate (Vmax) in red muscles, whereas the Km was similar in the two muscle types. High-intensity training and hyperthyroidism increased the lactate/H+ transport capacity by enhancing Vmax without affecting Km. Similarly, a reduced transport capacity with old age and hypothyroidism was due to a decrease in Vmax. The denervation-induced decline in lactate/H+ transport capacity resulted from both an increased Km and a reduced Vmax. The present data show that muscle type differences and most changes in the lactate/H+ transport capacity are mediated by modifications in Vmax, which is expected to represent the number of membrane transporter molecules. Km is unaffected by most treatments and appears to be independent of fibre type.

M3 - Journal article

C2 - 9683729

VL - 436

SP - 560

EP - 564

JO - Pflügers Archiv - European Journal of Physiology

JF - Pflügers Archiv - European Journal of Physiology

SN - 0031-6768

IS - 4

ER -