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. + + + + + + + + +
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Peti-Peterdi J; Bebok Z; Lapointe JY; Darwin Bell P
  • Volume

  • 282
  • Issue

  • 2 51-2