Consequences of potassium recycling in the renal medulla. Effects of ion transport by the medullary thick ascending limb of Henle's loop

J Clin Invest. 1982 Aug;70(2):219-29. doi: 10.1172/jci110609.


The consequences of K recycling and accumulation in the renal medulla were examined by measuring the effect of elevated K concentration on ion transport by the medullary thick ascending limb of Henle's loop. Perfused and bathed in vitro, thick limbs from both mouse and rabbit displayed a graded, reversible reduction of transepithelial voltage after increasing K concentration from 5 to 10, 15, or 25 mM. The effect was reproducible whether osmolality was 328 or 445 mosmol/kg H2O, and whether K replaced Na or choline. Net chloride absorption and transepithelial voltage were reduced by almost 90% when ambient K concentration was 25 mM. When either lumen or bath K was increased to 25 mM, net Na absorption was reduced. There was spontaneous net K absorption when perfusate and bath K concentration was 5 mM. Analysis of transepithelial K transfer after imposition of chemical gradients demonstrated rectification in the absorptive direction. Absorption of K by this segment provides a means to maintain high medullary interstitial concentration. Accumulation of K in the outer medulla, by reducing NaCl absorption, would increase volume flow through the loop of Henle and increase Na and water delivery to the distal nephron. K recycling thus might provide optimum conditions for K secretion by the distal nephron.

Publication types

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

MeSH terms

  • Absorption
  • Animals
  • Female
  • Ion Channels / metabolism*
  • Kidney Medulla / metabolism*
  • Kidney Tubules / metabolism*
  • Loop of Henle / metabolism*
  • Mathematics
  • Mice
  • Potassium / metabolism*
  • Rabbits
  • Time Factors


  • Ion Channels
  • Potassium