Watt Matthew J, Heigenhauser George J F, Spriet Lawrence L
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
J Physiol. 2003 Feb 15;547(Pt 1):301-8. doi: 10.1113/jphysiol.2002.034595. Epub 2002 Dec 20.
It has been proposed that hormone-sensitive lipase (HSL) regulates intramuscular triacylglycerol hydrolysis in skeletal muscle. The primary purpose of this study was to examine the early activation of HSL and the changes in the putative intramuscular and hormonal regulators of HSL activity at various aerobic exercise intensities. Eight male subjects cycled for 10 min at power outputs corresponding to 30, 60 and 90 % peak oxygen uptake (VO(2,peak)). Muscle samples were obtained at rest and following 1 and 10 min of exercise. Intramuscular triacylglycerol (mean +/- S.E.M.: 24.3 +/- 2.3 mmol (kg dry mass (DM))(-1)), long-chain fatty acyl CoA (13.9 +/- 1.4 micromol (kg DM)(-1)) and HSL activity (1.87 +/- 0.07 mmol min(-1) (kg DM)(-1))) were not different between trials at rest. HSL activity increased at 1 min of exercise at 30 and 60 % VO(2,peak), and to a greater extent at 90 % VO(2,peak). HSL activity remained elevated after 10 min of exercise at 30 and 60 % VO(2,peak), and decreased at 90 % VO(2,peak) from the rates observed at 1 min (1 min: 3.41 +/- 0.3 mmol min(-1) (kg DM)-1; 10 min: 2.92 +/- 0.26 mmol min(-1) (kg DM)(-1)), P < 0.05). There were no effects of exercise power output or time on long-chain fatty acyl CoA content. At 90 % VO(2,peak), skeletal muscle contents of ATP and phosphocreatine were decreased (P < 0.05), and free ADP and free AMP were increased (P < 0.05) during exercise. No changes in these metabolites occurred at 30 % VO(2,peak) and only modest changes were observed at 60 % VO(2,peak). Plasma adrenaline increased (P < 0.05) during exercise at 90 % VO(2,peak) only. These data suggest that a factor related to the onset of exercise (e.g. Ca2+) activates HSL early in exercise. Given the activation of HSL early in exercise, at a time when intramuscular triacylglycerol hydrolysis and fat oxidation are considered to be negligible, we propose that the control of intramuscular triacylglycerol hydrolysis is not solely related to the level of HSL activation, but must also be regulated by postactivational factors.
有人提出，激素敏感性脂肪酶（HSL）可调节骨骼肌内的三酰甘油水解。本研究的主要目的是检测HSL的早期激活情况，以及在不同有氧运动强度下，HSL活性的假定肌肉内调节因子和激素调节因子的变化。八名男性受试者以相当于峰值摄氧量（VO₂峰值）30%、60%和90%的功率输出进行10分钟的骑行。在静息状态以及运动1分钟和10分钟后采集肌肉样本。静息状态下，各试验组之间的肌肉内三酰甘油（平均值±标准误：24.3±2.3 mmol·(kg干质量（DM）)⁻¹）、长链脂肪酰辅酶A（13.9±1.4 μmol·(kg DM)⁻¹）和HSL活性（1.87±0.07 mmol·min⁻¹·(kg DM)⁻¹）无差异。在VO₂峰值30%和60%的运动1分钟时，HSL活性增加，在VO₂峰值90%时增加幅度更大。在VO₂峰值30%和60%的运动10分钟后，HSL活性仍保持升高，而在VO₂峰值90%时，HSL活性从1分钟时的水平下降（1分钟：3.41±0.3 mmol·min⁻¹·(kg DM)⁻¹；10分钟：2.92±0.26 mmol·min⁻¹·(kg DM)⁻¹），P<0.05）。运动功率输出或时间对长链脂肪酰辅酶A含量无影响。在VO₂峰值90%时，运动期间骨骼肌中的ATP和磷酸肌酸含量降低（P<0.05），游离ADP和游离AMP含量增加（P<0.05）。在VO₂峰值30%时，这些代谢物无变化，在VO₂峰值60%时仅观察到适度变化。仅在VO₂峰值90%的运动期间，血浆肾上腺素增加（P<0.05）。这些数据表明，与运动开始相关的一个因素（如Ca²⁺）在运动早期激活HSL。鉴于在运动早期HSL被激活，而此时肌肉内三酰甘油水解和脂肪氧化被认为可忽略不计，我们提出肌肉内三酰甘油水解的控制不仅与HSL激活水平有关，还必须受激活后因素的调节。
