Novel regulation of cell [Na(+)] in macula densa cells: apical Na(+) recycling by H-K-ATPase.

Academic Article

Abstract

  • Na-K-ATPase is the nearly ubiquitous enzyme that maintains low-Na(+), high-K(+) concentrations in cells by actively extruding Na(+) in exchange for K(+). The prevailing paradigm in polarized absorbing epithelial cells, including renal nephron segments and intestine, has been that Na-K-ATPase is restricted to the basolateral membrane domain, where it plays a prominent role in Na(+) absorption. We have found, however, that macula densa (MD) cells lack functionally and immunologically detectable amounts of Na-K-ATPase protein. In fact, these cells appear to regulate their cytosolic [Na(+)] via another member of the P-type ATPase family, the colonic form of H-K-ATPase, which is located at the apical membrane in these cells. We now report that this constitutively expressed apical MD colonic H-K-ATPase can function as a Na(H)-K-ATPase and regulate cytosolic [Na(+)] in a novel manner. This apical Na(+)-recycling mechanism may be important as part of the sensor function of MD cells and represents a new paradigm in cell [Na(+)] regulation.
  • Published In

    Keywords

  • Animals, Benzofurans, Colon, Enzyme Inhibitors, Ethers, Cyclic, Fluorescent Antibody Technique, Fluorescent Dyes, H(+)-K(+)-Exchanging ATPase, Hydrogen-Ion Concentration, Imidazoles, Kidney Glomerulus, Membrane Potentials, Ouabain, Rabbits, Sodium, Sodium-Potassium-Exchanging ATPase
  • Digital Object Identifier (doi)

    Pubmed Id

  • 17525821
  • Authorlist

  • Peti-Peterdi J; Bebok Z; Lapointe J-Y; Bell PD
  • Start Page

  • F324
  • End Page

  • F329
  • Volume

  • 282
  • Issue

  • 2