Stanton B A, Biemesderfer D, Wade J B, Giebisch G
Kidney Int. 1981 Jan;19(1):36-48. doi: 10.1038/ki.1981.5.
To examine the relationship between tubular transport of potassium and cell structure in segments of the superficial distal nephron, we performed potassium transport and quantitative electron microscopic studies in rats after potassium adaptation and potassium depletion. In distal nephrons continuously microperfused in vivo, potassium adaptation stimulated potassium secretion by 200%. Microperfused distal convoluted tubules (earliest portion of accessible distal nephron) did not, however, secrete potassium in potassium adapted animals. Morphometric analysis of the distal convoluted tubule also revealed no detectable effect of potassium diet on the structure of the distal cell type. In contrast, examination of the connecting tubule and the initial collecting tubule of the distal nephron demonstrated a striking increase in basolateral membrane in potassium-adapted animals. This change was limited to the connecting tubule cell and the principal cell type. No structural change of the intercalated cell type in either segment was associated with altered potassium transport. We conclude that cells of the distal convoluted tubule do not secrete potassium. Functional and morphologic evidence suggests that potassium is secreted by the connecting tubule cell and the principal cell of the connecting tubule and the initial collecting tubule, respectively.
为了研究浅表远端肾单位各节段中钾的肾小管转运与细胞结构之间的关系，我们对钾适应和钾缺乏的大鼠进行了钾转运和定量电子显微镜研究。在体内持续微量灌注的远端肾单位中，钾适应使钾分泌增加了200%。然而，在钾适应的动物中，微量灌注的远端曲小管（可及远端肾单位的最早期部分）并不分泌钾。对远端曲小管的形态计量分析也显示，钾饮食对远端细胞类型的结构没有可检测到的影响。相比之下，对远端肾单位的连接小管和初始集合小管的检查表明，在钾适应的动物中，基底外侧膜有显著增加。这种变化仅限于连接小管细胞和主细胞类型。两个节段中闰细胞类型的结构变化均与钾转运改变无关。我们得出结论，远端曲小管细胞不分泌钾。功能和形态学证据表明，钾分别由连接小管细胞以及连接小管和初始集合小管的主细胞分泌。
