Lönnerholm G, Wistrand P
Pediatr Res. 1982 Jun;16(6):407-11. doi: 10.1203/00006450-198206000-00002.
Lung tissue from human fetuses, with gestational ages ranging between 14-26 wk, was studied by histochemical and biochemical methods. The findings were similar in all tissues tested, without apparent correlation to gestational age. Staining that indicated carbonic anhydrase activity was found in the capillary endothelium and in the epithelium of some segments of the peripheral airways. The ciliated epithelium of the central airways was unstained. The distribution of the enzyme in the human fetal lung differed clearly from that in the adult human lung, where little or no enzyme has been found in the airway epithelium. The mean carbonic anhydrase activity in whole homogenates of fetal lung tissue was 24 enzyme units per g wet weight of tissue. Ninety % of this activity was recovered in the supernatant fraction. Assay of this fraction by a radioimmunosorbent technique showed the presence of the carbonic anhydrase isoenzyme HCA-C corresponding to 380 ng enzyme per mg tissue protein. Small amounts of HCA-B were also found but are thought to be attributable to contaminating erythrocytes; thus, the data suggest that both the capillary endothelium and the lung epithelium contain HCA-C, an isoenzyme of carbonic anhydrase known to be involved in electrolyte transport in many tissues.
采用组织化学和生物化学方法对妊娠14 - 26周人类胎儿的肺组织进行了研究。在所有检测的组织中结果相似，与胎龄无明显相关性。显示碳酸酐酶活性的染色见于毛细血管内皮和外周气道某些节段的上皮。中央气道的纤毛上皮未染色。该酶在人胎儿肺中的分布与成人肺明显不同，在成人肺的气道上皮中几乎未发现或未发现该酶。胎儿肺组织全匀浆中碳酸酐酶的平均活性为每克湿组织24个酶单位。90%的该活性在上清液部分中回收。通过放射免疫吸附技术对该部分进行检测，结果显示存在碳酸酐酶同工酶HCA - C，相当于每毫克组织蛋白含380纳克酶。还发现了少量的HCA - B，但认为这归因于污染的红细胞；因此，数据表明毛细血管内皮和肺上皮均含有HCA - C，这是一种已知参与许多组织中电解质转运的碳酸酐酶同工酶。
