Stahl W L, Broderson S H
J Histochem Cytochem. 1976 Jun;24(6):731-9. doi: 10.1177/24.6.181489.
Potassium-stimulated p-nitrophenylphosphatase (K+-pNPPase) activity was investigated in rat somatosensory cortex where 64-88% of enzymatic activity survived 5-10 min of fixation with 3% formaldehyde in 0.1 M cacodylate buffer, pH 7.4. Potassium-stimulated activity was inhibited by 1-10 mM ouabain. Levamisole (1.7 mM) inhibited brain alkaline phosphatase activity, facilitating the detection of K+-pNPPase activity. Strontium (10-20 mM) inhibited enzymatic activity by 38-75%. In parallel histochemical studies reaction product was found in strata, with cortical layers 2, 3, 4 and the outer portion of 5 containing the heaviest deposits. Highly reactive, vertically oriented, large diameter fibers were seen as groups between the outer portion of layer 5 and the pail surface. These fibers apparently arborize in the superficial layers. Smaller fibers were also positive and were oriented in various planes. The highest density of smaller, positive fibers occurred in layers 2 through 5. All positive fibers appeared to be axons or dendrites. Reaction product was not heavily concentrated in neuron perikarya or in glial elements. Sections did not contain reaction product when incubated in media lacking K+ or containing ouabain. The convergence of data from parallel histochemical and biochemical approaches supports the conclusion that the reactivity localized in the cerebral cortex represented the site of K+-pNPPase, a known component of the Na+,K+-adenosine triphosphatase complex. Neuronal processes demonstrated the highest enzymatic activity and may be most important in the active transport of Na+ and K+ in somatosensory cortex.
在大鼠体感皮层中研究了钾刺激的对硝基苯磷酸酶（K⁺-pNPPase）活性，其中64 - 88%的酶活性在用0.1 M二甲胂酸盐缓冲液（pH 7.4）配制的3%甲醛固定5 - 10分钟后仍能保留。1 - 10 mM哇巴因抑制钾刺激的活性。左旋咪唑（1.7 mM）抑制脑碱性磷酸酶活性，有助于检测K⁺-pNPPase活性。锶（10 - 20 mM）使酶活性抑制38 - 75%。在平行的组织化学研究中，反应产物见于各层，皮层第2、3、4层以及第5层外部沉积最密集。在第5层外部与桶状表面之间可见高反应性、垂直排列、大直径的纤维束。这些纤维显然在表层形成分支。较小的纤维也呈阳性，且排列在不同平面。较小的阳性纤维密度最高的区域在第2至5层。所有阳性纤维似乎都是轴突或树突。反应产物在神经元胞体或神经胶质成分中没有大量聚集。当在缺乏K⁺或含有哇巴因的培养基中孵育时，切片不含反应产物。来自平行组织化学和生化方法的数据汇聚支持这样的结论，即定位在大脑皮层的反应性代表了K⁺-pNPPase的位点，K⁺-pNPPase是钠钾腺苷三磷酸酶复合物的一个已知成分。神经元突起表现出最高的酶活性，可能在体感皮层中钠和钾的主动转运中最为重要。
