No acetyl group deficit is evident at the onset of exercise at 90% of maximal oxygen uptake in humans

作者：Marwood Simon^*; Constantin Teodosiu Dumitru; Casey Edel; Whyte Martin; Boobis Leslie; Bowtell Jo

来源：Journal of Sports Sciences, 2010, 28(3): 267-279.

DOI：10.1080/02640410903440884

• Acetyl group deficit
• dichloroacetate
• exercise
• near infrared spectroscopy
• muscle deoxygenation kinetics
• oxygen uptake kinetics

The existence of an acetyl group deficit at or above 90% of maximal oxygen uptake ((V) over dotO(2max)) has proved controversial, with contradictory results likely relating to limitations in previous research. The purpose of the present study was to determine whether the "acetyl group deficit'' occurs at the start of exercise at 90% (V) over dotO(2max) in a well-controlled study. Eight male participants (age: 33.6 +/- 2.0 years; (V) over dotO(2max): 3.60 +/- 0.21 litres.min(-1)) completed two exercise bouts at 90% (V) over dotO(2max) for 3 min following either 30 min of saline (control) or dichloroacetate (50 mg.kg(-1) body mass) infusion, ending 15 min before exercise. Muscle biopsies were obtained immediately before and after exercise while continuous non-invasive measures of pulmonary oxygen uptake and muscle deoxygenation were made. Muscle pyruvate dehydrogenase activity was significantly higher before exercise following dichloroacetate infusion (control: 2.67 +/- 0.98 vs. dichloroacetate: 17.9 +/- 1.1 mmol acetyl-CoA.min(-1).mg(-1) protein, P=0.01) and resulted in higher pre- and post-exercise muscle acetylcarnitine (pre-exercise control: 3.3 +/- 0.95 vs. pre-exercise dichloroacetate: 8.0 +/- 0.88 vs. post-exercise control: 11.9 +/- 1.1 vs. post-exercise dichloroacetate: 17.2 +/- 1.1 mmol.kg(-1) dry muscle, P<0.05). However, substrate-level phosphorylation (control: 125 +/- 20 vs. dichloroacetate: 113 +/- 13 mmol adenosine triphosphate.kg(-1) dry muscle) and (V) over dotO(2) kinetics (control: 19.2 +/- 2.2 vs. dichloroacetate: 22.8 +/- 2.5 s), were unaltered. Furthermore, dichloroacetate infusion blunted the slow component of (V) over dotO(2) and muscle deoxygenation and slowed muscle deoxygenation kinetics, possibly by enhancing oxygen delivery during exercise. These data support the hypothesis that the "acetyl group deficit'' does not occur at or above 90% (V) over dotO(2max).

• 出版日期2010