Kushmerick M J, Moerland T S, Wiseman R W
Department of Radiology, University of Washington, Seattle.
Adv Exp Med Biol. 1993;332:749-60; discussion 760-1. doi: 10.1007/978-1-4615-2872-2_66.
Phosphorus NMR spectroscopy and HPLC analyses were made on isolated rat and mouse muscles selected for different volume fractions of the major known fiber types. We tested the hypothesis that muscle cell types at rest have intrinsically different contents of PCr, ATP and Pi. The Pi content was low and the PCr and ATP contents were high in muscles with large contents of type 2b and 2a fibers, and vice versa in muscles with large volume fraction of types 1 and 2x fibers. From the profile of these metabolites we could distinguish only two classes of fibers in the murine muscles and predict well the composition of cat muscles. For the first class, types 2a and 2b fibers, the intracellular concentrations were: ATP 8 mM; total Cr 39 mM; PCr 32 mM; Pi 0.8 mM; ADP 8 microM. For the second class, type 1 and 2x fibers, these quantities are: ATP 5 mM; TCr 23 mM; PCr 16 mM; Pi 6 mM; ADP 11 microM. Thus our results establish a new and apparently general criterion upon which to distinguish skeletal muscle cells, one based on the resting content of bioenergetically important metabolites.
对从大鼠和小鼠中分离出的、具有不同已知主要纤维类型体积分数的肌肉进行了磷核磁共振光谱分析和高效液相色谱分析。我们检验了这样一个假设，即静息状态下的肌肉细胞类型在磷酸肌酸（PCr）、三磷酸腺苷（ATP）和无机磷酸盐（Pi）的含量上存在本质差异。在含有大量2b型和2a型纤维的肌肉中，Pi含量较低，PCr和ATP含量较高；反之，在含有大量1型和2x型纤维的肌肉中则相反。根据这些代谢物的分布情况，我们在小鼠肌肉中只能区分出两类纤维，并且能够很好地预测猫肌肉的组成。对于第一类，即2a型和2b型纤维，细胞内浓度分别为：ATP 8毫摩尔；总肌酸（TCr）39毫摩尔；PCr 32毫摩尔；Pi 0.8毫摩尔；二磷酸腺苷（ADP）8微摩尔。对于第二类，即1型和2x型纤维，这些量分别为：ATP 5毫摩尔；TCr 23毫摩尔；PCr 16毫摩尔；Pi 6毫摩尔；ADP 11微摩尔。因此，我们的结果建立了一种新的、显然具有普遍性的区分骨骼肌细胞的标准，该标准基于生物能量学重要代谢物的静息含量。
