title: Pyruvate dehydrogenase activity and acetyl group accumulation during exercise after different diets.
abstract: Pyruvate dehydrogenase activity (PDHa) and acetyl group accumulation were examined in human skeletal muscle at rest and during exercise after different diets. Five males cycled at 75% of maximal O2 uptake (VO2 max) to exhaustion after consuming a low-carbohydrate diet (LCD) for 3 days and again 1-2 wk later for the same duration after consuming a high-carbohydrate diet (HCD) for 3 days. Resting PDHa was lower after a LCD (0.20 +/- 0.04 vs. 0.69 +/- 0.05 mmol.min-1.kg wet wt-1; P < 0.05) and coincided with a greater intramuscular acetyl-CoA-to-CoASH ratio, acetyl-CoA content, and acetylcarnitine content. PDHa increased during exercise in both conditions but at a lower rate in the LCD condition compared with the HCD condition (1.46 +/- 0.25 vs. 2.65 +/- 0.23 mmol.min-1.kg wet wt-1 at 16 min and 1.88 +/- 0.20 vs. 3.11 +/- 0.14 at the end of exercise; P < 0.05). During exercise muscle acetyl-CoA and acetylcarnitine content and the acetyl-CoA-to-CoASH ratio decreased in the LCD condition but increased in the HCD condition. Under resting conditions PDHa was influenced by the availability of fat or carbohydrate fuels acting through changes in the acetyl-CoA-to-CoASH ratio. However, during exercise the activation of PDHa occurred independent of changes in the acetyl-CoA-to-CoASH ratio, suggesting that other factors are more important.
authors.affiliation: Department of Medicine, McMaster University Medical Centre, Hamilton, Ontario, Canada.
authors.forename: C T
authors.initials: CT
authors.lastname: Putman
authors.forename: L L
authors.initials: LL
authors.lastname: Spriet
authors.forename: E
authors.initials: E
authors.lastname: Hultman
authors.forename: M I
authors.initials: MI
authors.lastname: Lindinger
authors.forename: L C
authors.initials: LC
authors.lastname: Lands
authors.forename: R S
authors.initials: RS
authors.lastname: McKelvie
authors.forename: G
authors.initials: G
authors.lastname: Cederblad
authors.forename: N L
authors.initials: NL
authors.lastname: Jones
authors.forename: G J
authors.initials: GJ
authors.lastname: Heigenhauser
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000107:Acetylation; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003065:Coenzyme A / Q000378:metabolism; D004032:Diet; D004040:Dietary Carbohydrates; D015444:Exercise; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005990:Glycerol / Q000097:blood; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D009132:Muscles / Q000098:blood supply / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption; D005082:Physical Exertion; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D012039:Regional Blood Flow
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007773:Lactates; D011768:Pyruvate Dehydrogenase Complex; D000105:Acetyl Coenzyme A; D006003:Glycogen; D005990:Glycerol; D003065:Coenzyme A