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|87||Exercise-induced pyruvate dehydrogenase activation is not affected by 7 days of bed rest.|
Kiilerich K; Ringholm S; Bienso RS; Fisher JP; Iversen N; van Hall G; Wojtaszewski JF; Saltin B; Lundby C; Calbet JA; Pilegaard H
J Appl Physiol 2011; 111(3): 751-7
PubMed ID: 21680880
To test the hypothesis that physical inactivity impairs the exercise-induced modulation of pyruvate dehydrogenase (PDH), six healthy normally physically active male subjects completed 7 days of bed rest. Before and immediately after the bed rest, the subjects completed an oral glucose tolerance test (OGTT) and a one-legged knee extensor exercise bout [45 min at 60% maximal load (W(max))] with muscle biopsies obtained from vastus lateralis before, immediately after exercise, and at 3 h of recovery. Blood samples were taken from the femoral vein and artery before and after 40 min of exercise. Glucose intake elicited a larger (P = 0.05) insulin response after bed rest than before, indicating glucose intolerance. There were no differences in lactate release/uptake across the exercising muscle before and after bed rest, but glucose uptake after 40 min of exercise was larger (P = 0.05) before bed rest than after. Muscle glycogen content tended to be higher (0.05< P = 0.10) after bed rest than before, but muscle glycogen breakdown in response to exercise was similar before and after bed rest. PDH-E1alpha protein content did not change in response to bed rest or in response to the exercise intervention. Exercise increased (P = 0.05) the activity of PDH in the active form (PDHa) and induced (P = 0.05) dephosphorylation of PDH-E1alpha on Ser(2)(3), Ser(2) and Ser(3), with no difference before and after bed rest. In conclusion, although 7 days of bed rest induced whole body glucose intolerance, exercise-induced PDH regulation in skeletal muscle was not changed. This suggests that exercise-induced PDH regulation in skeletal muscle is maintained in glucose-intolerant (e.g., insulin resistant) individuals.