title: Exercise-induced pyruvate dehydrogenase activation is not affected by 7 days of bed rest.
abstract: 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-E1α 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-E1α on Ser²⁹³, Ser²⁹⁵ and Ser³⁰⁰, 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.
authors.affiliation: August Krogh Bldg., Dept. of Biology, Universitetsparken 13, 2100 Copenhagen, Denmark. kkiilerich@gmail.com
authors.forename: Kristian
authors.initials: K
authors.lastname: Kiilerich
authors.forename: Stine
authors.initials: S
authors.lastname: Ringholm
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Biensø
authors.forename: James P
authors.initials: JP
authors.lastname: Fisher
authors.forename: Ninna
authors.initials: N
authors.lastname: Iversen
authors.forename: Gerrit
authors.initials: G
authors.lastname: van Hall
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
authors.forename: Bengt
authors.initials: B
authors.lastname: Saltin
authors.forename: Carsten
authors.initials: C
authors.lastname: Lundby
authors.forename: Jose A L
authors.initials: JA
authors.lastname: Calbet
authors.forename: Henriette
authors.initials: H
authors.lastname: Pilegaard
mesh_terms: D000328:Adult; D001510:Bed Rest; D001706:Biopsy; D001786:Blood Glucose / Q000378:metabolism; D004789:Enzyme Activation; D015444:Exercise; D005080:Exercise Test; D015971:Gene Expression Regulation, Enzymologic; D018149:Glucose Intolerance / Q000097:blood / Q000378:metabolism; D005951:Glucose Tolerance Test; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009119:Muscle Contraction; D010101:Oxygen Consumption; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000378:metabolism*; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase / Q000235:genetics / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D052097:Quadriceps Muscle / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D012694:Serine; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012333:RNA, Messenger; D019344:Lactic Acid; D012694:Serine; D006003:Glycogen; D030481:Pyruvate Dehydrogenase (Lipoamide); C065640:pyruvate dehydrogenase E1alpha subunit; D017346:Protein Serine-Threonine Kinases; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase