Holtzman D, Mulkern R, Tsuji M, Cook C, Meyers R
Department of Neurology, Children's Hospital, Boston, MA 02115, USA.
Dev Neurosci. 1996;18(5-6):535-41. doi: 10.1159/000111451.
Rates of adenosine triphosphate (ATP) metabolism are higher in cerebral gray matter than in white matter. Like other excitable tissues, brain contains a phosphocreatine (PCr)/creatine kinase (CK)/ATP system including cytosolic (B-CK) and mitochondrial (Mi-CK) isozymes. High B-CK activity is present in white and gray matter while Mi-CK is mostly in gray matter. An in situ localizing 31P-NMR technique, one-dimensional chemical shift imaging (1D-CSI), has been used to study the PCr/CK/ATP system in these regions. In the metabolically mature 4-week-old piglet, the PCr/nucleoside triphosphate (NTP) ratio measured by the 1D-CSI technique is at least 50% higher in white than gray matter. Total creatine (Cr), ATP, and total NTP concentrations are the same in rapidly frozen rat white and gray matter, suggesting that PCr/Cr ratio is much higher in white matter. The PCr increases more in gray than white matter between 4 days and 4 weeks of age in piglet brain. The CK catalyzed reaction rate constant, measured by combining the saturation transfer experiment with the 1D-CSI, is also much higher in white than gray matter at both ages. The postnatal maturational increase in the CK rate constant is greater in gray matter. In summary, these differences in PCr concentration and CK reaction rates and isozymes characterize two physiologically different PCr/CK/ATP systems in gray and white matter.
脑灰质中三磷酸腺苷（ATP）的代谢速率高于白质。与其他可兴奋组织一样，脑含有一个磷酸肌酸（PCr）/肌酸激酶（CK）/ATP系统，包括胞质（B-CK）和线粒体（Mi-CK）同工酶。白质和灰质中均存在高B-CK活性，而Mi-CK主要存在于灰质中。一种原位定位31P-NMR技术，即一维化学位移成像（1D-CSI），已被用于研究这些区域的PCr/CK/ATP系统。在代谢成熟的4周龄仔猪中，通过1D-CSI技术测得的PCr/核苷三磷酸（NTP）比值在白质中比灰质中至少高50%。快速冷冻的大鼠白质和灰质中总肌酸（Cr）、ATP和总NTP浓度相同，这表明白质中PCr/Cr比值更高。在仔猪脑4日龄至4周龄期间，灰质中PCr的增加比白质中更多。通过将饱和转移实验与1D-CSI相结合测得的CK催化反应速率常数，在两个年龄段的白质中也均比灰质中高得多。灰质中CK速率常数的出生后成熟增加更大。总之，PCr浓度、CK反应速率和同工酶的这些差异表征了灰质和白质中两个生理上不同的PCr/CK/ATP系统。
