Regulation of Na(+)-K(+)-ATPase expression in cultured renal cells by incubation in hypertonic medium.
To determine whether alterations in cell volume affect Na(+)-K(+)-adenosinetriphosphatase (ATPase) expression, a subclone of the Madin-Darby canine kidney (MDCK) cell line was incubated in anisotonic serum-free medium and alpha- and beta-subunit mRNA, Na(+)-K(+)-ATPase activity, and active K+ transport were measured. In medium adjusted to 500 mosmol/kgH2O by adding NaCl, the alpha-subunit mRNA concentration was 2.93 +/- 0.14 (SE) times control and beta-mRNA was 1.93 +/- 0.27 times control. When sucrose was added to increase osmolality, alpha-subunit mRNA increased to 1.85 +/- 0.18 times control. Na(+)-K(+)-ATPase activity of homogenates from cells incubated in 500 mosmol/kgH2O medium for 24 h increased to 2.62 +/- 0.52 times control when NaCl was added and 2.31 +/- 0.34 times control when sucrose was added. Active K+ transport increased between 60 and 90% after cells were incubated in 450 mosmol/kgH2O medium with either NaCl or sucrose added. Stimulation of Na(+)-K(+)-ATPase expression in renal cells facing hypertonic stress may represent a long-term mechanism that allows cells to maintain cation gradients in a hypertonic environment.
Bowen
J W
JW
Department of Pharmacology, University of Missouri-Columbia School of Medicine 65212.
D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D003470:Culture Media; D006982:Hypertonic Solutions / Q000494:pharmacology*; D007038:Hypotonic Solutions / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012413:Rubidium / Q000493:pharmacokinetics; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*
D003470:Culture Media; D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D012333:RNA, Messenger; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D011188:Potassium