Guo Z, Burguera B, Jensen M D
Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Appl Physiol (1985). 2000 Nov;89(5):2057-64. doi: 10.1152/jappl.2000.89.5.2057.
A pulse ([(14)C]palmitate)-chase ([(3)H]palmitate) approach was used to study intramuscular triglyceride (imTG) fatty acid and plasma free fatty acid (FFA) kinetics during exercise at approximately 45% peak O(2) consumption in 12 adults. Vastus lateralis muscle was biopsied before and after 90 min of bicycle exercise; (3)H(2)O production, breath (14)CO(2) excretion and lipid oxidation (indirect calorimetry) rates were measured during exercise.
during exercise, 8.2+/-1.2 and 8.4+/-0.7 micromol x kg(-1) x min(-1) of imTG fatty acids and plasma FFA, respectively, were oxidized according to isotopic measurements. The sum of these two values was not different (P = 0.6) from lipid oxidation by indirect calorimetry (15.4 +/-1.6 micromol x kg(-1) x min(-1)); the isotopic and indirect calorimetry values were correlated (r = 0.79, P<0.005). During exercise, imTG turnover rate was 0.32+/-0.07%/min (6.0+/-2.0 micromol of imTG x kg wet muscle(-1) x min(-1)) and plasma FFA were incorporated into imTG at a rate of 0.7+/-0.1 micromol x kg wet muscle(-1) x min(-1). The imTG pool size did not change during exercise. This pulse-chase, dual tracer appears to be a reasonable approach to measure oxidation and synthesis kinetics of imTG.
采用脉冲（[¹⁴C]棕榈酸）-追踪（[³H]棕榈酸）方法，研究了12名成年人在约45%峰值耗氧量运动期间的肌内甘油三酯（imTG）脂肪酸和血浆游离脂肪酸（FFA）动力学。在90分钟自行车运动前后对股外侧肌进行活检；运动期间测量了³H₂O生成、呼气¹⁴CO₂排泄和脂质氧化（间接量热法）速率。
运动期间，根据同位素测量，imTG脂肪酸和血浆FFA分别氧化8.2±1.2和8.4±0.7微摩尔·千克⁻¹·分钟⁻¹。这两个值的总和与间接量热法测得的脂质氧化值（15.4±1.6微摩尔·千克⁻¹·分钟⁻¹）无差异（P = 0.6）；同位素和间接量热法值相关（r = 0.79，P<0.005）。运动期间，imTG周转率为0.32±0.07%/分钟（6.0±2.0微摩尔imTG·千克湿肌肉⁻¹·分钟⁻¹），血浆FFA以0.7±0.1微摩尔·千克湿肌肉⁻¹·分钟⁻¹的速率掺入imTG。运动期间imTG池大小未改变。这种脉冲-追踪双示踪剂似乎是测量imTG氧化和合成动力学的合理方法。
