University of Copenhagen, Universitetsparken 13, 2100 Denmark.
Pflugers Arch. 1998 Jul;436(4):560-4. doi: 10.1007/s004240050672.
Lactate/H+ transport kinetics were determined by means of the pH-sensitive probe BCECF in sarcolemmal giant vesicles, obtained from rat skeletal muscle, and related to variations in lactate/H+ transport capacity. Vesicle preparations were made from red and white muscles, mixed muscles, denervated muscles, muscles of old rats and rats that had been subjected to high-intensity training, endurance training, repeated exposure to hypoxia, and hypothyroid or hyperthyroid treatments. The lactate/H+ transport capacity of red muscles was greater than that of white muscles, and this difference was associated with a higher maximal transport rate (V max) in red muscles, whereas the K m was similar in the two muscle types. High-intensity training and hyperthyroidism increased the lactate/H+ transport capacity by enhancing V max without affecting K m. Similarly, a reduced transport capacity with old age and hypothyroidism was due to a decrease in V max. The denervation-induced decline in lactate/H+ transport capacity resulted from both an increased K m and a reduced V max. The present data show that muscle type differences and most changes in the lactate/H+ transport capacity are mediated by modifications in V max, which is expected to represent the number of membrane transporter molecules. K m is unaffected by most treatments and appears to be independent of fibre type.
通过 pH 敏感探针 BCECF 在大鼠骨骼肌衍生的肌浆网囊泡中测定了乳酸/ H+转运动力学，并与乳酸/ H+转运能力的变化相关联。囊泡制剂由红肌、白肌、混合肌、去神经肌肉、老年大鼠肌肉和接受高强度训练、耐力训练、反复缺氧暴露以及甲状腺功能减退或甲状腺功能亢进治疗的大鼠肌肉制成。红肌的乳酸/ H+转运能力大于白肌，这种差异与红肌中更高的最大转运速率（V max）有关，而两种肌肉类型的 K m 相似。高强度训练和甲状腺功能亢进通过增强 V max 而不影响 K m 来增加乳酸/ H+转运能力。同样，随着年龄的增长和甲状腺功能减退导致的转运能力降低是由于 V max 的降低所致。去神经诱导的乳酸/ H+转运能力下降是由于 K m 的增加和 V max 的降低所致。目前的数据表明，肌肉类型的差异和乳酸/ H+转运能力的大多数变化都是通过 V max 的改变来介导的，这预计代表膜转运体分子的数量。K m 不受大多数治疗的影响，并且似乎与纤维类型无关。
