Kaissling B
Klin Wochenschr. 1985 Sep 16;63(18):868-76. doi: 10.1007/BF01738139.
The distal segments beyond the macula densa--distal convoluted tubule, connecting tubule, cortical collecting duct--display cellular heterogeneity. The four different cell types, namely the DCT cell, CNT cell, the principal cell and intercalated cell differ mainly by the pattern of membrane amplification and they reveal also qualitative differences as to some cytoplasmic proteins. Each of the four cell types adapts to chronic changes in electrolyte metabolism with structural alteration, concerning essentially the membrane area over which the active transport step of the cell proceeds, in DCT-, CNT- and P-cells the basolateral cell membrane with the Na-K-ATPase, in intercalated cells the luminal cell membrane with a H+ ATPase. Since each cell type responds only to specific conditions with changes in membrane area and associated transcellular transport activity, morphological studies can help to determine the specific role of each cell type in the regulation of renal electrolyte excretion. Such investigations demonstrated that besides mineralocorticoid hormones the transport capacity of certain cells should depend on the solute composition of tubular fluid. Thus, changes in the transport pattern specifically induced in only one segment alters also the transport patterns of segments downstream. Cellular heterogeneity seems to guarantee the optimal regulation of renal electrolyte excretion.
致密斑远端的节段——远曲小管、连接小管、皮质集合管——表现出细胞异质性。四种不同的细胞类型，即远曲小管细胞、连接小管细胞、主细胞和闰细胞，主要在膜放大模式上存在差异，并且在一些细胞质蛋白方面也存在质的差异。四种细胞类型中的每一种都通过结构改变来适应电解质代谢的慢性变化，本质上涉及细胞进行主动转运步骤的膜面积，在远曲小管细胞、连接小管细胞和主细胞中是带有钠钾ATP酶的基底外侧细胞膜，在闰细胞中是带有氢离子ATP酶的管腔细胞膜。由于每种细胞类型仅通过膜面积变化和相关的跨细胞转运活性对特定条件作出反应，形态学研究有助于确定每种细胞类型在肾电解质排泄调节中的特定作用。此类研究表明，除了盐皮质激素外，某些细胞的转运能力应取决于肾小管液的溶质组成。因此，仅在一个节段中特异性诱导的转运模式变化也会改变下游节段的转运模式。细胞异质性似乎保证了肾电解质排泄的最佳调节。
