Juel C, Honig A, Pilegaard H
August Krogh Institute, University of Copenhagen, Denmark.
Acta Physiol Scand. 1991 Dec;143(4):361-5. doi: 10.1111/j.1748-1716.1991.tb09246.x.
Lactate transport was studied in sarcolemmal giant vesicles obtained from rat or rabbit skeletal muscle. With this technique it is possible to obtain quantitative information on sarcolemmal transport characteristics. In equilibrium exchange experiments with 10, 30 and 60 mM lactate, vesicles from 'red' rat muscles had a 50% higher lactate transport capacity than vesicles from 'white' muscles. Giant vesicles made from rabbit red muscles had a 39% higher lactate transport capacity than vesicles from white muscles. These differences probably reflect a different number of lactate transporters, whereas the lactate affinity in red and white muscles are identical. Lactate transport capacity decreased with age. Sarcolemmal giant vesicles made from 22-month-old rats had a 28% lower transport capacity than vesicles from 2-month old rats. In absolute terms, the initial exchange flux with 30 mM lactate was 92 and 127 pmol cm-2 sec-1 for old and young rats, respectively. In supplementary studies in which microelectrode measurements were made in single mouse muscle fibers, it was shown that the cellular acidification rate due to lactate incubation, was 38% lower in fibres from 18-month old mice than in fibres from 2-month old mice.
对从大鼠或兔骨骼肌获取的肌膜大囊泡中的乳酸转运进行了研究。利用这项技术能够获取有关肌膜转运特性的定量信息。在使用10 mM、30 mM和60 mM乳酸进行的平衡交换实验中，来自大鼠“红色”肌肉的囊泡的乳酸转运能力比来自“白色”肌肉的囊泡高50%。由兔红色肌肉制成的大囊泡的乳酸转运能力比来自白色肌肉的囊泡高39%。这些差异可能反映了乳酸转运体数量的不同，而红色和白色肌肉中乳酸的亲和力是相同的。乳酸转运能力随年龄下降。由22月龄大鼠制成的肌膜大囊泡的转运能力比2月龄大鼠的囊泡低28%。就绝对值而言，使用30 mM乳酸时，老年和幼年大鼠的初始交换通量分别为92和127 pmol cm-2 sec-1。在补充研究中，对单根小鼠肌纤维进行了微电极测量，结果表明，与2月龄小鼠的纤维相比，18月龄小鼠的纤维因乳酸孵育导致的细胞酸化速率低38%。
