Lönnerholm G, Midtvedt T, Schenholm M, Wistrand P J
Department of Medical Pharmacology, University of Uppsala, Sweden.
Acta Physiol Scand. 1988 Feb;132(2):159-66. doi: 10.1111/j.1748-1716.1988.tb08313.x.
Histochemical and immunocytochemical methods were used to study the presence of carbonic anhydrase (CA) isoenzymes in the caecum and colon of normal and germ-free rats. Very high enzyme activity was demonstrated by histochemistry in the caecum and proximal colon of normal rats, while the activity decreased in the distal colon. Very strong immunostaining for the isoenzyme CA I was found in the cytoplasm of surface cells and upper gland cells in the caecum and colon of normal rats. In the distal colon the staining was less intense with a marked cell-to-cell variation. Ca II was found in the apical (luminal) cell region of the surface epithelium in all regions. Ca III was possibly present in small amounts, but this could not be judged with certainty. There was no difference in carbonic anhydrase between normal and germ-free rats (except for less staining of the mucosal capillaries in germ-free animals). Therefore, our data give no support to the hypothesis that CA I participates in the absorption of microbial fermentation products. The location of CA II in the apical cell region suggests a role for this isoenzyme in regulation of the microclimate close to the epithelial cells.
采用组织化学和免疫细胞化学方法研究正常大鼠和无菌大鼠盲肠及结肠中碳酸酐酶（CA）同工酶的存在情况。组织化学显示，正常大鼠盲肠和近端结肠中酶活性非常高，而远端结肠中活性降低。在正常大鼠盲肠和结肠的表面细胞及上层腺细胞胞质中发现了对同工酶CA I的非常强的免疫染色。在远端结肠中，染色强度较低，且细胞间差异明显。在所有区域的表面上皮顶端（管腔）细胞区域均发现了Ca II。Ca III可能少量存在，但无法确定。正常大鼠和无菌大鼠之间的碳酸酐酶没有差异（除了无菌动物的黏膜毛细血管染色较少）。因此，我们的数据不支持CA I参与微生物发酵产物吸收的假说。Ca II在顶端细胞区域的定位表明该同工酶在调节上皮细胞附近微环境中起作用。
