Studies on terminal differentiation of rat renal proximal tubular cells in culture: ouabain-sensitive K and Na transport.
We have studied the ontogeny of Na-K ATPase-mediated Na and K transport in rat renal proximal tubular cells using electron probe analysis. The cells were cultured from kidneys of 10-day-old, young (Y), and 40-day-old, adult (A) rats. Before an experiment cells were Na-loaded and K-depleted by incubation in K-free medium. The maximum rate of ouabain-sensitive Na and K transport was measured after reactivating the Na-K pump by transferring the cells from K-free medium to medium containing 5 mM K. In cells cultured for 2 days, ouabain-sensitive Na and K net initial transport rates were significantly higher in A than in Y cells. Between 2 and 4 days in culture there was a significant decrease in ouabain-sensitive Na and K transport rates in both Y and A cells. From 2 to 4 days of culture there was, in Y but not in A cells, a significant decrease in K/Na ratio. The decrease in K/Na ratio was due to a significant increase in Na content. After incubation in K-free medium, net intracellular solute accumulation was observed in A and Y cells cultured for 4 days but not in A and Y cells cultured for 2 days. In conclusion, maximal Na- and K-pump-mediated transport increases during terminal differentiation. This increase can be measured in cells cultured for 2 days. With longer time in culture, Na-K pump activity decreases and the difference between A and Y cells is not measurable.(ABSTRACT TRUNCATED AT 250 WORDS)
Larsson
S H
SH
Harvard Medical School, Boston, MA.
Aperia
A
A
Lechene
C
C
D000367:Age Factors; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D004577:Electron Probe Microanalysis; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium