Increased total concentration of Na-K pumps in vastus lateralis muscle of old trained human subjects.
The concentration of Na-K pumps was measured as the total capacity for [3H]ouabain binding in needle biopsies of the vastus lateralis muscle. Samples were obtained from young (28 +/- 0.2 yr) and old (68 +/- 0.6 yr) untrained control subjects and from groups of age-matched old trained subjects, who had been performing well-defined training programs at regular intervals for 12-17 yr. Measurements of maximum isometric force in knee extension showed that running and, especially, strength training produced a significant increase, whereas swim training was without effect. Both running and swim training increased endurance of knee extension, whereas strength training had a negative effect. When compared with untrained age-matched subjects, the swim-, running-, and strength-trained subjects demonstrated increased concentration of [3H]ouabain binding sites of 30% (P less than 0.01), 32% (P less than 0.05), and 40% (P less than 0.05), respectively. In the entire group of 28 individuals tested, maximum isometric strength and the concentration of [3H]ouabain binding sites showed correlation (r = 0.49, P less than 0.01). This upregulation of Na-K pump concentration might contribute to the reduction in exercise-induced hyperkalemia seen in trained subjects.
Klitgaard
H
H
Institute of Physiology, University of Aarhus, Copenhagen, Denmark.
Clausen
T
T
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism; D001707:Biopsy, Needle; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000032:analysis* / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism; D010806:Physical Education and Training; D011188:Potassium / Q000032:analysis* / Q000378:metabolism; D012964:Sodium / Q000032:analysis* / Q000378:metabolism
D010042:Ouabain; D012964:Sodium; D011188:Potassium