Cytoskeleton disruption and apical redistribution of proximal tubule Na(+)-K(+)-ATPase during ischemia

Am J Physiol. 1992 Sep;263(3 Pt 2):F488-95. doi: 10.1152/ajprenal.1992.263.3.F488.


The polar distribution of Na(+)-K(+)-ATPase to the basolateral membrane of proximal tubule cells is essential for the efficient and vectorial reabsorption of Na+ and may be dependent on the formation of a metabolically stable, detergent-insoluble complex of Na(+)-K(+)-ATPase with the actin membrane cytoskeleton. The present studies utilized immunocytochemical techniques to demonstrate and quantify the apical redistribution of Na(+)-K(+)-ATPase during mild ischemia (15 min) that occurred in proximal (1.3 +/- 0.9 vs. 4.5 +/- 1.1 particles/100 microns surface membrane, P less than 0.01) but not distal tubule cells. Treatment of control apical membranes with 2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanoate (A2C), a fluidizing agent, markedly increased membrane fluidity without any effect on Na(+)-K(+)-ATPase activity. In brush-border membrane vesicles isolated after ischemia, however, A2C further increased an already elevated Na(+)-K(+)-ATPase activity. During ischemia, total cellular Na(+)-K(+)-ATPase activity remained unaltered, but the Triton X-100-soluble (noncytoskeleton associated) fraction of Na(+)-K(+)-ATPase increased significantly following 15 and 30 min. There was a corresponding decrease in the Triton X-100-insoluble fraction of Na(+)-K(+)-ATPase, with the ratio of detergent-soluble to -insoluble Na(+)-K(+)-ATPase increasing from 13 +/- 2 to 32 +/- 5% (P less than 0.01) during 30 min of ischemia. Western blot analysis of the Triton X-100-soluble fraction, following 30 min of ischemic injury, revealed the presence of Na(+)-K(+)-ATPase, actin, fodrin, and uvomorulin. However, in a fraction highly enriched for Na(+)-K(+)-ATPase, neither actin, fodrin, nor uvomorulin was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Fractionation
  • Cell Membrane / enzymology
  • Cytoskeleton / enzymology
  • Cytoskeleton / ultrastructure*
  • Detergents
  • Electrophoresis, Polyacrylamide Gel
  • Immunohistochemistry
  • Ischemia / enzymology*
  • Kidney Tubules, Proximal / enzymology*
  • Male
  • Octoxynol
  • Polyethylene Glycols
  • Rats
  • Rats, Sprague-Dawley
  • Renal Circulation*
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Solubility
  • Tissue Distribution


  • Detergents
  • Polyethylene Glycols
  • Octoxynol
  • Sodium-Potassium-Exchanging ATPase