Chloride-dependent potassium secretion in early and late renal distal tubules.

摘要: Potassium transport by subsegments of the rat surface distal tubule was studied using a modified in vivo microperfusion method. The nephron segments between 14 and 38% 62 83% total length distance macula densa region confluence with another) were perfused separately. first these two is composed primarily convoluted (DCT) cells; more segment made up initial collecting (ICT) epithelium. Experiments performed to measure potassium secretion via pathways: diffusion mechanism driven favorable electrochemical gradient for potassium, cotransport activated when lumen chloride concentration low. In series experiments, both DCT ICT secreted an artificial control solution resembling fluid normally present at beginning tubule. Absolute rates higher than DCT. Decreasing Cl stimulated second which ion concentrations raised levels found interstitial fluid. Under circumstances, lower segments. resulted those seen low chloride; as high series.(ABSTRACT TRUNCATED AT 250 WORDS)