Lönnerholm G, Ridderstråle Y
Kidney Int. 1980 Feb;17(2):162-74. doi: 10.1038/ki.1980.20.
The rat kidney was studied by light and electron microscope after it was histochemically stained for carbonic anhydrase activity. Glomeruli and Bowman's capsule were inactive. Convoluted proximal tubules showed intense activity at the brush border and the basolateral membranes. Cytoplasmic activity also was found. Straight proximal tubules had considerable enzyme activity at basolateral membranes but only low activity at the brush border and in the cytoplasm. In nephrons with long loops, the descending thin limb contained cytoplasmic enzyme activity, whereas the ascending thin limb was inactive. Thin limbs of short loops showed a varying enzyme pattern. In the thick limb of Henle's loop, most enzyme activity was found at the luminal cell border. Distal convoluted tubules showed enzyme activity only at basal infolded membranes. In the late distal tubule, intercalated cells appear among the "ordinary" distal cells, and they contained abundant cytoplasmic enzyme. Many highly active intercalated cells were found also in the cortical and outer medullary segments of the collecting duct. The chief cells in these segments also showed some cytoplasmic enzyme activity. In the inner medullary segment of the collecting duct, enzyme activity disappeared gradually, and the tip of the papilla lacked activity. Acetazolamide (10 microM) completely abolished visible staining, whereas Cl 13850 (10 microM), an inactive acetazolamide analogue, did not interfere with the staining.
对大鼠肾脏进行碳酸酐酶活性组织化学染色后，用光学显微镜和电子显微镜进行研究。肾小球和鲍曼囊无活性。曲部近端小管在刷状缘和基底外侧膜显示强烈活性。也发现了细胞质活性。直部近端小管在基底外侧膜有相当的酶活性，但在刷状缘和细胞质中只有低活性。在具有长襻的肾单位中，降支细段含有细胞质酶活性，而升支细段无活性。短襻的细段显示出不同的酶模式。在亨氏襻的粗段，大部分酶活性位于管腔细胞边界。远曲小管仅在基底褶膜处显示酶活性。在远曲小管后期，闰细胞出现在“普通”远曲小管细胞之间，它们含有丰富的细胞质酶。在集合管的皮质和外髓段也发现了许多高活性的闰细胞。这些段的主细胞也显示出一些细胞质酶活性。在集合管的内髓段，酶活性逐渐消失，乳头尖端无活性。乙酰唑胺（10微摩尔）完全消除了可见染色，而无活性的乙酰唑胺类似物Cl 13850（10微摩尔）不干扰染色。
