Thamer Claus, Machann Jürgen, Bachmann Oliver, Haap Michael, Dahl Dominik, Wietek Beate, Tschritter Otto, Niess Andreas, Brechtel Klaus, Fritsche Andreas, Claussen Claus, Jacob Stephan, Schick Fritz, Häring Hans-Ulrich, Stumvoll Michael
Department of Endocrinology and Metabolism, Eberhard-Karls-University, D-72076 Tübingen, Germany.
J Clin Endocrinol Metab. 2003 Apr;88(4):1785-91. doi: 10.1210/jc.2002-021674.
The existence of metabolically relevant intramyocellular lipids (IMCL) as assessed by the noninvasive (1)H-magnetic resonance spectroscopy (MRS) has been established. In the present studies, we analyzed the relationships between IMCL in two muscle types [the predominantly nonoxidative tibialis muscle (tib) and the predominantly oxidative soleus muscle (sol)] and anthropometric data, aerobic capacity (VO(2)max, bicycle ergometry, n = 77) and insulin sensitivity (hyperinsulinemic euglycemic clamp, n = 105) using regression analysis. In univariate regression, IMCL (tib) was weakly but significantly correlated with percentage of body fat (r = 0.28, P = 0.01), whereas IMCL (sol) was better correlated with waist-to-hip ratio (r = 0.41, P < 0.0001). No significant univariate correlation with age or maximal aerobic power was observed. After adjusting for adiposity, IMCL (tib) was positively correlated with measures of aerobic fitness. A significant interaction term between VO(2)max and percentage of body fat on IMCL (tib) (P = 0.04) existed (whole model r(2) = 0.26, P = 0.001). In contrast, aerobic fitness did not influence IMCL (sol). No correlation between insulin sensitivity as such and IMCL (tib) (r = -0.13, P = 0.2) or IMCL (sol) (r = 0.03, P = 0.72) was observed. Nethertheless, a significant interaction term between VO(2)max and IMCL on insulin sensitivity existed [P = 0.04 (tib) and P = 0.02 (sol)]; [whole model (sol) r(2) = 0.61, P < 0.0001, (tib) r(2) = 0.60, P < 0.0001]. In conclusion, obesity and aerobic fitness are important determinants of IMCL. IMCL and insulin sensitivity are negatively correlated in untrained subjects. The correlation between the two parameters is modified by the extent of aerobic fitness and cannot be found in endurance trained subjects. Thus, measurements of aerobic fitness and body fat are indispensable for the interpretation of IMCL and its relationship with insulin sensitivity.
通过无创氢磁共振波谱（MRS）评估的具有代谢相关性的肌内脂质（IMCL）的存在已得到证实。在本研究中，我们使用回归分析，分析了两种肌肉类型[主要为非氧化型的胫骨前肌（tib）和主要为氧化型的比目鱼肌（sol）]中的IMCL与人体测量数据、有氧能力（最大摄氧量VO₂max，自行车测力计，n = 77）和胰岛素敏感性（高胰岛素正常血糖钳夹，n = 105）之间的关系。在单变量回归中，IMCL（tib）与体脂百分比呈弱但显著的相关性（r = 0.28，P = 0.01），而IMCL（sol）与腰臀比的相关性更好（r = 0.41，P < 0.0001）。未观察到与年龄或最大有氧功率有显著的单变量相关性。在调整肥胖因素后，IMCL（tib）与有氧适能指标呈正相关。在IMCL（tib）上，最大摄氧量与体脂百分比之间存在显著的交互项（P = 0.04）（整个模型r² = 0.26，P = 0.001）。相比之下，有氧适能并未影响IMCL（sol）。未观察到胰岛素敏感性本身与IMCL（tib）（r = -0.13，P = 0.2）或IMCL（sol）（r = 0.03，P = 0.72）之间存在相关性。然而，在胰岛素敏感性上，最大摄氧量与IMCL之间存在显著的交互项[P = 0.04（tib）和P = 0.02（sol）]；[整个模型（sol）r² = 0.61，P < 0.0001，（tib）r² = 0.60，P < 0.0001]。总之，肥胖和有氧适能是IMCL的重要决定因素。在未经训练的受试者中，IMCL与胰岛素敏感性呈负相关。这两个参数之间的相关性会因有氧适能程度而改变，在耐力训练的受试者中未发现这种相关性。因此，有氧适能和体脂的测量对于解释IMCL及其与胰岛素敏感性的关系是必不可少的。
