Na,K-ATPase expression and cell volume during hypertonic stress in human renal cells.
Primary cultures of human renal cortex cells were incubated in hypertonic medium and low K+ medium to determine the effect on Na,K-ATPase alpha and beta subunit expression, cell water, and intracellular ions. Cells exhibited functional characteristics of proximal tubules based on PTH stimulation of cAMP and the presence of Na(+)-dependent phosphate transport. When either NaCl or sucrose was added to increase medium osmolality to 500 mOsm/kg, beta subunit mRNA increased relative to control between 2.4 and 3.2-fold by six hours, and was still near twofold higher after 24 hours, while alpha subunit mRNA increased to about 1.5 times control by six hours. In low K+ medium, only beta mRNA increased. Hypertonic incubation increased Na,K-ATPase activity by 39% to 66% after 24 hours. Cell water was 70% of control at one hour, but increased to 90% of control by 24 hours. Only about 40% of the volume regulatory increase depended on accumulation of Na+ and K+. These results demonstrate that primary cultures of human proximal tubule cells can respond to hypertonic stress by induction of Na,K-ATPase.
Department of Pharmacology, University of Missouri School of Medicine, Columbia.
M R
MR
Yordy
J W
JW
Bowen
D048429:Cell Size; D002478:Cells, Cultured; D015342:DNA Probes; D015870:Gene Expression; D006801:Humans; D006982:Hypertonic Solutions; D007424:Intracellular Fluid / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis* / Q000235:genetics
D015342:DNA Probes; D006982:Hypertonic Solutions; D012333:RNA, Messenger; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium