Peters S J, Harris R A, Wu P, Pehleman T L, Heigenhauser G J, Spriet L L
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Am J Physiol Endocrinol Metab. 2001 Dec;281(6):E1151-8. doi: 10.1152/ajpendo.2001.281.6.E1151.
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.
在6名健康男性摄入等热量的高脂肪/低碳水化合物（HF/LC；碳水化合物占总能量摄入的5%，脂肪占73%，蛋白质占22%）饮食后，测量其骨骼肌丙酮酸脱氢酶激酶（PDK）活性的增加情况，并与标准化的饮食前（碳水化合物占50%，脂肪占30%，蛋白质占21%）进行比较。在饮食前3天（第0天）以及HF/LC饮食1天、2天和3天后，从股外侧肌获取活检样本。从新鲜肌肉中提取完整的线粒体，分析其PDK活性以及PDK2和PDK4蛋白的蛋白质印迹。在每个时间点进行第二次活检并冷冻，用于PDK2和PDK4 mRNA的Northern印迹分析。在为期3天的HF/LC饮食期间，PDK活性呈线性增加，且在第1天时显著高于对照组。在第0天、1天、2天和3天时，PDK活性分别为0.09±0.03、0.18±0.05、0.30±0.07和0.37±0.09 min⁻¹。PDK4蛋白和mRNA在第1天时最大程度增加，而PDK2蛋白和mRNA不受HF/LC饮食影响。HF/LC饮食1天后静息呼吸交换率降低（从0.79±0.02降至0.72±0.02），并且在为期3天的饮食干预期间一直保持较低水平（0.68±0.01）。向脂肪利用的即刻转变伴随着血液甘油、β-羟基丁酸和血浆游离脂肪酸浓度的增加。这些结果表明，在为期3天的HF/LC饮食期间PDK活性的持续增加并非由于1天后PDK蛋白的增加。这可能是由于另一种同工型对总PDK活性的贡献，或者是由于PDK4或PDK2比活性的持续增加。
