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Effect of hypoxia on glucose metabolism in human skeletal muscle during exercise

1989; Wiley; Volume: 136; Issue: 3 Linguagem: Inglês

10.1111/j.1748-1716.1989.tb08678.x

1365-201X

Abram Katz, Kent Sahlin,

Cardiovascular and exercise physiology

The effect of respiratory hypoxia on muscle glucose metabolism during short‐term dynamic exercise has been investigated. Eight men cycled for 5 min at 120 ± 6 W (mean ± SE), which corresponded to 50% of maximal O 2 uptake during normoxia (N), breathing air (N) on one occasion and 11 % O 2 (hypoxia ‐ H) on the other. Biopsies were taken from the quadriceps femoris muscle before and after exercise. Oxygen uptake during exercise was not affected by H. The arterial blood glucose concentration during N exercise remained constant, but increased from 4.62 ± 0.11 mmol l ‐1 at rest to 5.22 ± 0.19 mmol l ‐1: at the end of H exercise (P < 0.05 vs N exercise). The intracellular glucose content at rest was low and did not change during N exercise, but was four times higher after exercise during H vs N (P < 0.01). Glucose 6‐P increased under both conditions but significantly more during H (P < 0.01), while glucose 1,6‐P 2 was not significantly different between treatments either at rest or after exercise. It is concluded that: (1) glucose uptake by skeletal muscle during short‐term exercise during H is not associated with a stoichiometric glucose utilization; (2) the inhibition of hexokinase during H (evidenced by increase in muscle glucose) is due primarily to the increase in glucose 6‐P; and (3) glucose 1,6‐P 2 is of minor importance for the regulation of contraction‐mediated flux through hexokinase in human skeletal muscle.