Kriketos A D, Pan D A, Lillioja S, Cooney G J, Baur L A, Milner M R, Sutton J R, Jenkins A B, Bogardus C, Storlien L H
Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
Am J Physiol. 1996 Jun;270(6 Pt 2):R1332-9. doi: 10.1152/ajpregu.1996.270.6.R1332.
There is evidence that insulin resistance and obesity are associated with relative increases in the proportion of glycolytic type IIb muscle fibers and decreases in the proportion of oxidative type I fibers. Futhermore, insulin resistance and obesity are associated with the fatty acid (FA) profile of structural membrane lipids. The present study was undertaken to define interrelationships between muscle fiber type and oxidative capacity, muscle membrane FA composition, and insulin action and obesity. Muscle morphology, insulin action, and body fat content were measured in 48 male nondiabetic Pima Indians. Percent body fat (pFAT, determined by hydrodensitometry) correlated negatively with percentage of type I fibers (r = -0.44, P = 0.002) and positively with percentage of type IIb fibers (r = 0.40, P = 0.005). Consistent with this finding, pFAT was also significantly related to oxidative capacity of muscle, as assessed by NADH staining (r = -0.47, P = 0.0007) and citrate synthase (CS) activity (r = -0.43, P = 0.008). Insulin action was correlated with oxidative capacity (CS; r = 0.41, P = 0.01) and weakly correlated with percentage of type IIb fibers (r = -0.29, P = 0.05). In addition, relationships were shown between muscle fiber type and FA composition (e.g., percentage of type I fibers related to n-3 FA; r = 0.37, P = 0.01). Thus leaness and insulin sensitivity are associated with increased oxidative capacity and unsaturation of membranes in skeletal muscle. Present studies support the hypothesis that muscle oxidative capacity and fiber type may play a genetically determined or an environmentally modified role in development of obesity and insulin resistance.
有证据表明，胰岛素抵抗和肥胖与糖酵解型IIb肌纤维比例的相对增加以及氧化型I纤维比例的降低有关。此外，胰岛素抵抗和肥胖与结构膜脂质的脂肪酸（FA）谱有关。本研究旨在确定肌纤维类型与氧化能力、肌膜FA组成、胰岛素作用和肥胖之间的相互关系。对48名非糖尿病男性皮马印第安人测量了肌肉形态、胰岛素作用和体脂含量。体脂百分比（pFAT，通过水下密度测定法确定）与I型纤维百分比呈负相关（r = -0.44，P = 0.002），与IIb型纤维百分比呈正相关（r = 0.40，P = 0.005）。与这一发现一致，pFAT也与通过NADH染色评估的肌肉氧化能力显著相关（r = -0.47，P = 0.0007）和柠檬酸合酶（CS）活性（r = -0.43，P = 0.008）。胰岛素作用与氧化能力（CS；r = 0.41，P = 0.01）相关，与IIb型纤维百分比弱相关（r = -0.29，P = 0.05）。此外，还显示了肌纤维类型与FA组成之间的关系（例如，I型纤维百分比与n-3 FA相关；r = 0.37，P = 0.01）。因此，瘦和胰岛素敏感性与骨骼肌膜氧化能力的增加和不饱和性有关。目前的研究支持这样的假设，即肌肉氧化能力和纤维类型可能在肥胖和胰岛素抵抗的发展中发挥基因决定或环境修饰的作用。
