Grisar T, Frere J M, Franck G
Brain Res. 1979 Apr 6;165(1):87-103. doi: 10.1016/0006-8993(79)90047-7.
Progress curves of the enzymatic reactions show that ATPases of bulk isolated glial cells, perikarya and synaptosomes exhibit hysteretic change. Initial velocities of enzyme activities were therefore obtained according to the equation valid for the hysteretic model. The (Na+, K+)-ATPase activities of the same brain fractions were measured before or after NaI treatment. Only glial and synaptosomal enzyme could be adequately extracted by using this procedure. Attempts to purify the (Na+, K+)-ATPase from brain perikarya by NaI extraction were unsuccessful. In order to determine the effect of the K+ ions on enzymic physiological efficiency (phys. eff.; i.e., the ratio Vmax/Kmapp) the variation of (Na+, K+)-ATPase activities from each brain fraction was measured as a function of Mg.ATP2- concentration in the presence of 5 and 20 mM K+ ions. High K+ ion concentrations (20 mM) increased the physiological efficiency of glial enzyme and decreased the same kinetic parameter in neuronal (perikaryal as well as synaptosomal) enzyme preparations. Results are discussed in relation to a possible distribution of distinct enzyme in different brain cell populations as well as a possible role of glial cells in an active regulation of K+ ion extracellular fluid in the CNS.
酶促反应的进程曲线表明，大量分离的胶质细胞、胞体和突触体中的ATP酶呈现滞后变化。因此，根据适用于滞后模型的方程获得酶活性的初始速度。在碘化钠处理之前或之后测量相同脑部分的（钠，钾）-ATP酶活性。使用该程序只能充分提取胶质和突触体酶。通过碘化钠提取从脑胞体中纯化（钠，钾）-ATP酶的尝试未成功。为了确定钾离子对酶生理效率（生理效率；即Vmax/Kmapp比值）的影响，在存在5和20 mM钾离子的情况下，测量每个脑部分的（钠，钾）-ATP酶活性随Mg.ATP2-浓度的变化。高钾离子浓度（20 mM）提高了胶质酶的生理效率，并降低了神经元（胞体以及突触体）酶制剂中的相同动力学参数。讨论了结果与不同脑细胞群体中不同酶的可能分布以及胶质细胞在中枢神经系统中主动调节细胞外液钾离子的可能作用的关系。
