Enhanced rectal potassium secretion in chronic renal insufficiency: evidence for large intestinal potassium adaptation in man

Clin Sci (Lond). 1986 Oct;71(4):393-401. doi: 10.1042/cs0710393.


The role of the large intestine in K+ excretion in chronic renal insufficiency was studied with a rectal dialysis technique in 14 normal subjects and eight normokalaemic, normotensive patients with chronic renal insufficiency. At initial intraluminal K+ concentrations of 10, 20, 30 and 45 mmol/l, net K+ secretion in patients with renal insufficiency was significantly greater than in normal subjects by approximately 1.8 mumol h-1 cm-2. The increase in net K+ secretion was more marked in those patients with creatinine clearances of less than 10 ml/min. In contrast, there were no significant differences in net Na+ and water transport, transmucosal potential difference and plasma aldosterone concentrations between the two groups. With an initial intraluminal K+ concentration of 30 mmol/l, the addition of amiloride (final concentration 1 mmol/l) to the rectal lumen decreased net Na+ absorption and transmucosal potential difference in normal subjects by 69% (P less than 0.005) and 31% (P less than 0.005) respectively, and in patients with renal insufficiency by 75% (P less than 0.05) and 36% (P less than 0.05) respectively, but there was no change in net K+ secretion in either group. These results indicate that the K+ secretory capacity of the rectal mucosa increases in chronic renal insufficiency, and the large intestine may therefore contribute to the maintenance of K+ homoeostasis as renal K+ excretion declines. Increased rectal K+ secretion in renal insufficiency occurs independently of changes in plasma K+ and aldosterone concentrations, net Na+ absorption and transmucosal potential difference, and may reflect stimulation of an active K+ secretory process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aldosterone / blood
  • Amiloride / pharmacology
  • Creatinine / blood
  • Dialysis
  • Female
  • Humans
  • Intestinal Absorption / drug effects
  • Intestinal Mucosa / metabolism
  • Kidney Failure, Chronic / metabolism*
  • Male
  • Membrane Potentials
  • Middle Aged
  • Potassium / metabolism*
  • Rectum / metabolism*
  • Sodium / metabolism


  • Aldosterone
  • Amiloride
  • Sodium
  • Creatinine
  • Potassium