Punyadeera Chamindie, Zorenc Antoine H G, Koopman René, McAinch Andrew J, Smit Egbert, Manders Ralph, Keizer Hans A, Cameron-Smith David, van Loon Luc J C
Department of Pathology, Research Institute GROW, Maastricht University, Maastricht, The Netherlands.
Eur J Endocrinol. 2005 Mar;152(3):427-36. doi: 10.1530/eje.1.01872.
It has been suggested that adiponectin regulates plasma free fatty acid (FFA) clearance by stimulating FFA uptake and/or oxidation in muscle. We aimed to determine changes in plasma adiponectin concentration and adiponectin receptor 1 and 2 mRNA expression in skeletal muscle during and after prolonged exercise under normal, fasting conditions (high FFA trial; HFA) and following pharmacological inhibition of adipose tissue lipolysis (low FFA trial; LFA). Furthermore, we aimed to detect and locate adiponectin in skeletal muscle tissue.
Ten subjects performed two exercise trials (120 min at 50% VO(2max)). Indirect calorimetry was used to determine total fat oxidation rate. Plasma samples were collected at rest, during exercise and during post-exercise recovery to determine adiponectin, FFA and glycerol concentrations. Muscle biopsies were taken to determine adiponectin protein and adiponectin receptor 1 and 2 mRNA expression and to localise intramyocellular adiponectin.
Basal plasma adiponectin concentrations averaged 6.57+/-0.7 and 6.63+/-0.8 mg/l in the HFA and LFA trials respectively, and did not change significantly during or after exercise. In the LFA trial, plasma FFA concentrations and total fat oxidation rates were substantially reduced. However, plasma adiponectin and muscle adiponectin receptor 1 and 2 mRNA expression did not differ between trials. Immunohistochemical staining of muscle cross-sections showed the presence of adiponectin in the sarcolemma of individual muscle fibres and within the interfibrillar arterioles.
Plasma adiponectin concentrations and adiponectin receptor 1 and 2 mRNA expression in muscle are not acutely regulated by changes in adipose tissue lipolysis and/or plasma FFA concentrations. Adiponectin is abundantly expressed in muscle, and, for the first time, it has been shown to be present in/on the sarcolemma of individual muscle fibres.
有人提出脂联素通过刺激肌肉摄取和/或氧化游离脂肪酸（FFA）来调节血浆游离脂肪酸清除率。我们旨在确定在正常禁食条件下长时间运动期间及之后（高游离脂肪酸试验；HFA）以及在药物抑制脂肪组织脂解后（低游离脂肪酸试验；LFA），血浆脂联素浓度以及骨骼肌中脂联素受体1和2 mRNA表达的变化。此外，我们旨在检测并定位骨骼肌组织中的脂联素。
10名受试者进行了两项运动试验（以50%最大摄氧量进行120分钟运动）。采用间接测热法测定总脂肪氧化率。在静息、运动期间和运动后恢复期间采集血浆样本，以测定脂联素、游离脂肪酸和甘油浓度。采集肌肉活检样本以测定脂联素蛋白以及脂联素受体1和2 mRNA表达，并对细胞内脂联素进行定位。
在HFA和LFA试验中，基础血浆脂联素浓度分别平均为6.57±0.7和6.63±0.8 mg/l，在运动期间及之后均未发生显著变化。在LFA试验中，血浆游离脂肪酸浓度和总脂肪氧化率大幅降低。然而，试验之间血浆脂联素以及肌肉脂联素受体1和2 mRNA表达并无差异。肌肉横断面的免疫组织化学染色显示，在单个肌纤维的肌膜以及肌原纤维间小动脉内存在脂联素。
血浆脂联素浓度以及肌肉中脂联素受体1和2 mRNA表达不受脂肪组织脂解和/或血浆游离脂肪酸浓度变化的急性调节。脂联素在肌肉中大量表达，并且首次被证明存在于单个肌纤维的肌膜上。
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