title: Ionic transport in individual renal epithelial cells from adult and young rats.
abstract: Renal epithelial cells were isolated from the outermost superficial cortex of adult and young rats. The cells, likely of proximal origin, were plated on silicon pieces, and cultured during 1-3 days. Intracellular content and concentrations of K, Na, Cl, and P, and the kinetics of change in intracellular content, after inhibition of Na-K ATPase by incubation with ouabain or in K-free medium, were measured in individual cells in small populations using electron probe analysis. In control medium, concentrations in mM were approximately: K, 130; Na, 15; Cl, 28; P, 140. After 6 h inhibition of Na-K ATPase, cells exchanged all K for Na, and the intracellular Na concentration increased to 139 mM in K-free medium. The Cl concentration increased at most to 46 mM. The sum of intracellular K + Na + Cl did not increase more than 25% after 24 h incubation in K-free medium. There were no differences in intracellular K, Na, and Cl for adult and young rat cells in similar conditions. The half-times of K efflux and Na influx after inhibition of Na-K ATPase measured in adult rat were approximately 16-20 min. In the absence of serum, in K-free medium, the half-times of K efflux and Na influx in young rat cells were approximately 30 min, significantly higher than the half-time in the presence of serum, and with ouabain, being approximately 13 min. Histograms of distributions of K and Na content showed that the cells behaved as a single functional population. Ouabain Ki was estimated to be 10(-4) M. After 24 h preincubation in K-free medium, when returned in 5 mM K-containing medium, adult rat cells recovered rapidly normal intracellular K and Na concentrations. Using this approach, expression of the kinetics ionic transport properties of renal epithelial cells during development, and the hormonal influences on terminal differentiation may be studied.
mesh_terms: D000367:Age Factors; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured; D004577:Electron Probe Microanalysis; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D007477:Ions / Q000032:analysis / Q000502:physiology*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000502:physiology*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007477:Ions; D010042:Ouabain