Characterization of aldosterone-induced potassium secretion in rat distal colon

J Clin Invest. 1989 Mar;83(3):844-51. doi: 10.1172/JCI113967.


The role of apical and basolateral membranes in aldosterone-induced active potassium (K) secretion in rat distal colon was investigated by measuring mucosal-to-serosal (Jms) and serosal-to-mucosal (Jsm) 42K fluxes ( across isolated stripped mucosa under short-circuit conditions in normal and secondary-hyperaldosterone animals. In normal colons mucosal tetraethylammonium (TEA; 30 mM) or barium (Ba; 5 mM), but not cesium (Cs; 15 mM), reduced Jsm without affecting Jms. In aldosterone animals (a) net K secretion (-0.54 +/- 0.11) was converted to net K absorption (0.63 +/- 0.15) by mucosal TEA, which produced a marked reduction in Jsm (0.82 +/- 0.07) and an increase in Jms (0.35 +/- 0.07). In contrast mucosal Ba resulted in a relatively smaller reduction in JK(sm) without altering JK(ms), whereas mucosal Cs was ineffective; (b) serosal bumetanide or the removal of serosal Na or Cl markedly inhibited JK(sm and abolished net K secretion; and (c) serosal ouabain (1 mM) produced qualitatively similar effects to those of serosal bumetanide. These results demonstrate that (a) normal rat distal colon contains apical TEA- and Ba-sensitive K channels; (b) aldosterone induces TEA-sensitive and Ba-sensitive apical K channels; (c) aldosterone-induced K secretion requires both the Na,K-pump and Na-K-2Cl cotransport for K uptake across the basolateral membrane; and (d) alteration of any of these processes results in inhibition of aldosterone-induced active K secretion simultaneously with stimulation of K absorption.

Publication types

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

MeSH terms

  • Aldosterone / pharmacology*
  • Animals
  • Barium / pharmacology
  • Bumetanide / pharmacology
  • Cell Membrane / physiology
  • Cesium / pharmacology
  • Chlorides / pharmacology
  • Colon / drug effects
  • Colon / metabolism*
  • Intestinal Absorption
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / metabolism
  • Male
  • Ouabain / pharmacology
  • Potassium / metabolism*
  • Potassium Channels / drug effects
  • Potassium Channels / physiology
  • Rats
  • Rats, Inbred Strains
  • Sodium / metabolism
  • Sodium / pharmacology
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology


  • Chlorides
  • Potassium Channels
  • Tetraethylammonium Compounds
  • Bumetanide
  • Cesium
  • Barium
  • Aldosterone
  • Ouabain
  • Tetraethylammonium
  • Sodium
  • Potassium