McCullagh K J, Poole R C, Halestrap A P, Tipton K F, O'Brien M, Bonen A
Department of Anatomy, Trinity College Dublin, Ireland.
Am J Physiol. 1997 Aug;273(2 Pt 1):E239-46. doi: 10.1152/ajpendo.1997.273.2.E239.
We examined whether chronic stimulation of red and white rat muscles increased the concentrations of the monocarboxylate transporter MCT1. Red and white tibialis anterior (RTA and WTA, respectively) and extensor digitorum longus (EDL) muscles were chronically stimulated via the peroneal nerve for 7 days. Stimulated and contralateral control muscles were examined for MCT1 content, L-lactate uptake, lactate dehydrogenase (LDH) isoforms, and muscle fiber composition. MCT1 was 1.5 times greater in stimulated RTA, 3 times greater in stimulated WTA, and 1.9 times greater in stimulated EDL compared with respective control muscles (P < 0.05). L-Lactate uptake increased in all stimulated muscles (P < 0.05), and this was highly correlated with the increase in MCT1 (r = 0.96). The heart-type LDH (H-LDH) subunits also increased in all stimulated muscles (P < 0.05). The H-LDH subunits correlated highly with MCT1 in the muscles (r = 0.83). There was no change in muscle-type LDH subunits (P > 0.05). There were negligible alterations in muscle fiber composition in the stimulated muscles, suggesting that the increase in MCT1 was independent of changes in muscle fiber composition. These studies are the first to demonstrate that chronic muscle contraction increases MCT1 concentrations in both red and white skeletal muscles.
我们研究了对大鼠红肌和白肌的慢性刺激是否会增加单羧酸转运蛋白MCT1的浓度。通过腓总神经对红、白胫前肌（分别为RTA和WTA）以及趾长伸肌（EDL）进行为期7天的慢性刺激。检测受刺激肌肉和对侧对照肌肉的MCT1含量、L-乳酸摄取、乳酸脱氢酶（LDH）同工型以及肌纤维组成。与各自的对照肌肉相比，受刺激的RTA中MCT1含量高1.5倍，受刺激的WTA中高3倍，受刺激的EDL中高1.9倍（P<0.05）。所有受刺激肌肉的L-乳酸摄取均增加（P<0.05），且这与MCT1的增加高度相关（r = 0.96）。所有受刺激肌肉中心型LDH（H-LDH）亚基也增加（P<0.05）。肌肉中的H-LDH亚基与MCT1高度相关（r = 0.83）。肌肉型LDH亚基无变化（P>0.05）。受刺激肌肉的肌纤维组成变化可忽略不计，这表明MCT1的增加与肌纤维组成的变化无关。这些研究首次证明慢性肌肉收缩会增加红肌和白肌中MCT1的浓度。
