Terjung R L, Koerner J E
Am J Physiol. 1976 May;230(5):1194-7. doi: 10.1152/ajplegacy.1976.230.5.1194.
The cytochrome c concentrations of the different types of skeletal muscle of trained and nontrained normal and thyroidectomized rats were measured. Animals were trained by treadmill running 1 mph, at a 15% incline, 1 h/day, 5 days/wk for at least 12 wk. This training program induced an expected 50% increase in cytochrome c in the high-oxidative fast-twitch red (FTR) and slow-twitch red (STR) fibers and only a 25% increase in the low-oxidative fast-twitch white (FTW) fibers of the normal rats. This same training program caused a greater increase (100%) in the FTR and STR fibers of the thyroidectomized runners and a dramatic 243% increase in the FTW fiber. Even though the thyroidectomy procedure caused a reduction in oxidative capacity of all types of skeletal muscle fibers to about one-half normal, the absolute increase in cytochrome c in the muscles of the trained thyroidectomized animals was essentially the same or greater than that of the normal trained animals. These results indicate that the adaptive response to training of an increased oxidative capacity in skeletal muscle occurs in the absence of normal thyroid function. They also suggest that the exercise bouts of the thyroidectomized animals were performed with a relatively greater involvement of the FTW muscle fibers.
对训练和未训练的正常大鼠以及甲状腺切除大鼠不同类型骨骼肌中的细胞色素c浓度进行了测量。动物通过在跑步机上以1英里/小时的速度、15%的坡度、每天1小时、每周5天的方式进行训练，持续至少12周。该训练方案使正常大鼠的高氧化型快肌红纤维（FTR）和慢肌红纤维（STR）中的细胞色素c增加了预期的50%，而低氧化型快肌白纤维（FTW）仅增加了25%。相同的训练方案使甲状腺切除的跑步大鼠的FTR和STR纤维有更大的增加（100%），FTW纤维则急剧增加了243%。尽管甲状腺切除手术使所有类型骨骼肌纤维的氧化能力降低至正常水平的约二分之一，但训练后的甲状腺切除动物肌肉中细胞色素c的绝对增加量与正常训练动物基本相同或更大。这些结果表明，在缺乏正常甲状腺功能的情况下，骨骼肌对训练产生的氧化能力增加的适应性反应依然会发生。它们还表明，甲状腺切除动物的运动回合中FTW肌纤维的参与程度相对更高。
