Endurance training, expression, and physiology of LDH, MCT1, and MCT4 in human skeletal muscle
Endurance training, expression, and physiology of LDH, MCT1, and MCT4 in human skeletal muscle
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DOI：
10.1152/ajpendo.2000.278.4.e571
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发表时间：
2000-04-01
影响因子：
5.1
通讯作者：
Brooks, GA
中科院分区：
文献类型：
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作者：
Dubouchaud, H;Butterfield, GE;Brooks, GA
为了评估耐力训练对人股外侧肌单羧酸转运体（MCT）表达的影响，我们比较了训练前后总肌肉制备物（MU）和肌膜富集（SL）和肌膜富集（MI）组分中MCT 1和MCT 4的含量。为了确定肌肉乳酸盐释放和氧化的变化是否与训练诱导的MCT表达变化相关，我们将蛋白质印迹中的条带密度与体内测定的乳酸盐动力学相关联。9周腿部循环耐力训练[75%峰值耗氧量（（V）over dot o（2 peak））]增加了肌肉柠檬酸合酶活性（+75%，P < 0.05）和I型肌球蛋白重链百分比（+50%，P < 0.05）; MU乳酸脱氢酶-5（M4）同工酶百分比下降（-12%，P < 0.05）。在SL和MI组分中检测到MCT 1，MCT 4定位于SL。肌肉MCT 1含量在训练前后受试者之间是一致的;相反，MCT 4含量表现出很大的个体间差异。训练后MU、SL和MI的MCT 1含量显著增加（分别为+90%、+60%和+78%），而SL的MCT 4含量在训练后增加（+47%，P < 0.05），但MU的MCT 4含量没有增加。线粒体MCT 1含量与静息时小腿净乳酸释放呈负相关（r =-0.85，P < 0.02）。肌膜MCT 1和MCT 4含量与65%（V）/dot o（2 peak）运动5 min时小腿净乳酸释放量呈显著正相关（r分别为0.76，P < 0.03和0.86，P < 0.01）。结果支持以下结论：1）耐力训练增加了肌肉中MCT 1的表达，因为MCT 1插入肌膜和线粒体膜，2）训练对肌膜MCT 4有不同的影响，3）MCT 1和MCT 4都参与细胞-细胞乳酸穿梭，而MCT 1促进细胞内乳酸穿梭的操作。
To evaluate the effects of endurance training on the expression of monocarboxylate transporters (MCT) in human vastus lateralis muscle, we compared the amounts of MCT1 and MCT4 in total muscle preparations (MU) and sarcolemma-enriched (SL) and mitochondria-enriched (MI) fractions before and after training. To determine if changes in muscle lactate release and oxidation were associated with training-induced changes in MCT expression, we correlated band densities in Western blots to lactate kinetics determined in vivo. Nine weeks of leg cycle endurance training [75% peak oxygen consumption ((V) over dot o(2peak))] increased muscle citrate synthase activity (+75%, P < 0.05) and percentage of type I myosin heavy chain (+50%, P < 0.05); percentage of MU lactate dehydrogenase-5 (M4) isozyme decreased (-12%, P < 0.05). MCT1 was detected in SL and MI fractions, and MCT4 was localized to the SL. Muscle MCT1 contents were consistent among subjects both before and after training; in contrast, MCT4 contents showed large interindividual variations. MCT1 amounts significantly increased in MU, SL, and MI after training (+90%, +60%, and +78%, respectively), whereas SL but not MU MCT4 content increased after training (+47%, P < 0.05). Mitochondrial MCT1 content was negatively correlated to net leg lactate release at rest (r = -0.85, P < 0.02). Sarcolemmal MCT1 and MCT4 contents correlated positively to net leg lactate release at 5 min of exercise at 65% (V) over dot o(2peak) (r = 0.76, P < 0.03 and r = 0.86, P < 0.01, respectively). Results support the conclusions that 1) endurance training increases expression of MCT1 in muscle because of insertion of MCT1 into both sarcolemmal and mitochondrial membranes, 2) training has variable effects on sarcolemmal MCT4, and 3) both MCT1 and MCT4 participate in the cell-cell lactate shuttle, whereas MCT1 facilitates operation of the intracellular lactate shuttle.