Human skeletal muscle PDH kinase activity and isoform expression during a 3-day high-fat/low-carbohydrate diet.
The increase in skeletal muscle pyruvate dehydrogenase kinase (PDK) activity was measured in skeletal muscle of six healthy males after a eucaloric high-fat/low-carbohydrate (HF/LC; 5% carbohydrate, 73% fat, and 22% protein of total energy intake) diet compared with a standardized prediet (50% carbohdyrate, 30% fat, and 21% protein). Biopsies were obtained from the vastus lateralis muscle after 3 days on the prediet (day 0) and after 1, 2, and 3 days of the HF/LC diet. Intact mitchondria were extracted from fresh muscle and analyzed for PDK activity and Western blotting of PDK2 and PDK4 protein. A second biopsy was taken at each time point and frozen for Northern blot analysis of PDK2 and PDK4 mRNAs. PDK activity increased in a linear fashion over the 3-day HF/LC diet and was significantly higher than control by 1 day. PDK activity was 0.09 +/- 0.03, 0.18 +/- 0.05, 0.30 +/- 0.07, and 0.37 +/- 0.09 min(-1) at 0, 1, 2, and 3 days, respectively. PDK4 protein and mRNA increased maximally by day 1, and PDK2 protein and mRNA were unaffected by the HF/LC diet. Resting respiratory exchange ratios decreased after 1 day of the HF/LC diet (from 0.79 +/- 0.02 to 0.72 +/- 0.02) and remained depressed throughout the 3-day dietary intervention (0.68 +/- 0.01). The immediate shift to fat utilization was accompanied by increased blood glycerol, beta-hydroxybutyrate, and plasma free fatty acid concentrations. These results suggest that the continuing increase in PDK activity over the 3-day HF/LC diet is not due to increasing PDK protein beyond 1 day. This could be due to the contribution of another isoform to the total PDK activity or to a continual increase in PDK4 or PDK2 specific activity.
Peters
S J
SJ
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada. speters@arnie.pec.brocku.ca
Harris
R A
RA
Wu
P
P
Pehleman
T L
TL
Heigenhauser
G J
GJ
Spriet
L L
LL
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005990:Glycerol / Q000097:blood; D006801:Humans; D006885:Hydroxybutyrates / Q000097:blood; D007328:Insulin / Q000097:blood; D007527:Isoenzymes / Q000096:biosynthesis; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000502:physiology; D018482:Muscle, Skeletal / Q000201:enzymology*; D011494:Protein Kinases / Q000096:biosynthesis*; D017346:Protein Serine-Threonine Kinases; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012333:RNA, Messenger / Q000096:biosynthesis
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D007328:Insulin; D007527:Isoenzymes; C000631430:PDK2 protein, human; C000631432:PDK4 protein, human; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012333:RNA, Messenger; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D005990:Glycerol