Luminal influences on potassium secretion: Chloride, sodium, and thiazide diuretics

Heino Velázquez, David Ellison, Fred S. Wright

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28 Scopus citations


In the presence of Cl-, K+ secretion by the distal tubule saturates with increasing luminal Na+ concentration. Apparent maximal K+ secretion is attained with luminal Na+ concentrations of 40 mM. The results of the present study show that lowering the Cl- concentration of luminal fluid can increase the level of Na+-stimulated K+ secretion beyond the maximal level attained in the presence of Cl-. The effect of lowering luminal Cl- concentration to + secretion is greater with higher Na+ concentration. Under these conditions, chlorothiazide decreases K+ secretion. When chlorothiazide is present, changing the Na+ concentration does not affect K+ secretion. Because in rats a thiazide effect is attributed primarily to the distal convoluted tubule (DCT), we postulate that it is primarily DCT cells that increase K+ secretion when Na+ concentration is raised in the presence of low luminal Cl- concentration. We propose that the rat DCT cells have both an absorptive Na+-Cl- cotransport mechanism and a secretory K+-Cl- cotransport mechanism in the luminal membrane that can mediate the apparent exchange of Na+ for K+.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Issue number6 31-6
Publication statusPublished - 1992
Externally publishedYes



  • Chlorothiazide
  • Distal convoluted tubule
  • Gluconate
  • Kidney
  • Potassium-chloride cotransport
  • Rat
  • Sodium-chloride cotransport
  • Transport

ASJC Scopus subject areas

  • Physiology

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