Distal tubular segments of the rabbit kidney after adaptation to altered Na- and K-intake. I. Structural changes.
The baso-lateral cell-membrane area in kidney tubules appears to be associated with the capacity for electrolyte transport; in the rabbit, it decreases from the distal convoluted tubule (DCT-cells) over the connecting tubule (CNT-cells) to the cortical collecting duct (principal cells). Adaptation to low Na-, high K-intake changes this pattern: CNT-cells at the beginning of the connecting tubule have the highest membrane area, which decreases along the segment, but remains two-fold higher than in controls. Principal cells have a four-fold higher membrane area than in controls. Simultaneous treatment with the antimineralocorticoid canrenoate-K inhibits the structural changes in CNT-cells only in end-portions of the connecting tubule and in principal cells. After prolonged high Na-, low K-intake DCT-cells display a two-fold higher membrane area than controls, while CNT-cells and principal cells are not affected. Simultaneous treatment with DOCA does not affect the DCT-cells but provokes a moderate increase in membrane area in CNT-cells, and a 5.5-fold increase in principal cells. The data provide evidence that DCT-, CNT- and principal cells are functionally different cell types. The baso-lateral cell-membrane area, associated with electrolyte-transport capacity, appears to be influenced in DCT-cells mainly by Na-intake, in CNT-cells mainly by K-intake and in part also by mineralocorticoids, and in principal cells mainly by mineralocorticoids.
D000222:Adaptation, Physiological; D000450:Aldosterone / Q000097:blood; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D003900:Desoxycorticosterone / Q000494:pharmacology; D004032:Diet; D004039:Diet, Sodium-Restricted; D005260:Female; D007684:Kidney Tubules / Q000648:ultrastructure*; D007685:Kidney Tubules, Collecting / Q000648:ultrastructure; D007686:Kidney Tubules, Distal / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D011188:Potassium / Q000008:administration & dosage* / Q000652:urine; D011817:Rabbits; D012964:Sodium / Q000008:administration & dosage* / Q000652:urine
D003900:Desoxycorticosterone; D000450:Aldosterone; D012964:Sodium; D011188:Potassium