Odland L M, Heigenhauser G J, Spriet L L
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
J Appl Physiol (1985). 2000 Dec;89(6):2352-8. doi: 10.1152/jappl.2000.89.6.2352.
This study examined the effects of elevated free fatty acid (FFA) provision on the regulation of pyruvate dehydrogenase (PDH) activity and malonyl-CoA (M-CoA) content in human skeletal muscle during moderate-intensity exercise. Seven men rested for 30 min and cycled for 10 min at 40% and 10 min at 65% of maximal O(2) uptake while being infused with either Intralipid and heparin (Int) or saline (control). Muscle biopsies were taken at 0, 1 (rest-to-exercise transition), 10, and 20 min. Exercise plasma FFA were elevated (0.99 +/- 0.11 vs. 0.33 +/- 0.03 mM), and the respiratory exchange ratio was reduced during Int (0.87 +/- 0.02) vs. control (0.91 +/- 0.01). PDH activation was lower during Int at 1 min (1.33 +/- 0.19 vs. 2.07 +/- 0.14 mmol. min(-1). kg(-1) wet muscle) and throughout exercise. Muscle pyruvate was reduced during Int at rest [0.17 +/- 0.03 vs. 0.25 +/- 0.03 mmol/kg dry muscle (dm)] but increased above control during exercise. NADH was higher during Int vs. control at rest and 1 min of exercise (0.122 +/- 0.016 vs. 0.102 +/- 0.005 and 0.182 +/- 0.016 vs. 0.150 +/- 0.016 mmol/kg dm), but not at 10 and 20 min. M-CoA was lower during Int vs. control at rest and 20 min of exercise (1.12 +/- 0.22 vs. 1.43 +/- 0.17 and 1.33 +/- 0.16 vs. 1.84 +/- 0.17 micromol/kg dm). The reduced PDH activation with elevated FFA during the rest-to-exercise transition was related to higher mitochondrial NADH at rest and 1 min of exercise and lower muscle pyruvate at rest. The decreased M-CoA may have increased fat oxidation during exercise with elevated FFA by reducing carnitine palmitoyltransferase I inhibition and increasing mitochondrial FFA transport.
本研究探讨了在中等强度运动期间，提高游离脂肪酸（FFA）供应对人骨骼肌中丙酮酸脱氢酶（PDH）活性调节及丙二酰辅酶A（M-CoA）含量的影响。7名男性休息30分钟后，以最大摄氧量的40%骑行10分钟，再以65%的最大摄氧量骑行10分钟，期间分别输注英脱利匹特和肝素（Int）或生理盐水（对照组）。在0、1（从休息到运动转换时）、10和20分钟时采集肌肉活检样本。运动期间Int组血浆FFA升高（0.99±0.11 vs. 0.33±0.03 mM），呼吸交换率在Int组（0.87±0.02）低于对照组（0.91±0.01）。Int组在1分钟时（1.33±0.19 vs. 2.07±0.14 mmol·min⁻¹·kg⁻¹湿肌肉）及整个运动过程中PDH激活较低。休息时Int组肌肉丙酮酸降低[0.17±0.03 vs. 0.25±0.03 mmol/kg干肌肉（dm）]，但运动期间高于对照组。休息时及运动1分钟时Int组NADH高于对照组（0.122±0.016 vs. 0.102±0.005和0.182±0.016 vs. 0.150±0.016 mmol/kg dm），但在10和20分钟时无差异。休息时及运动20分钟时Int组M-CoA低于对照组（1.12±0.22 vs. 1.43±0.17和1.33±0.16 vs. 1.84±0.17 μmol/kg dm）。从休息到运动转换期间FFA升高导致的PDH激活降低与休息时及运动1分钟时较高的线粒体NADH以及休息时较低的肌肉丙酮酸有关。M-CoA降低可能通过减少肉碱棕榈酰转移酶I抑制并增加线粒体FFA转运，从而在FFA升高的运动期间增加脂肪氧化。
