What is responsible for the diurnal variation in potassium excretion?

A. Steele, H. deVeber, S. E. Quaggin, A. Scheich, J. Ethier, M. L. Halperin*

*Corresponding author for this work

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

Potassium excretion exhibits a diurnal pattern, with most excretion occurring close to noon in humans. Each component of the K+ excretion rate [urinary K+ concentration ([K+]) and flow rate] was measured and back- calculated to reflect events in the cortical collecting duct (CCD). Our purpose was to determine to what extent each component contributed to this diurnal variation in each 2-h portion of the day. In humans, K+ excretion rose threefold from nadir (0600 h) to peak (1200-1400 h), 18 h after the principal intake of K+. The variation in K+ excretion was due almost exclusively to changes in [K+] in the terminal CCD ([K+](CCD)) rather than via changes in flow rate. In rats, the bulk of K+ excretion occurred shortly after eating. Both components of K+ excretion rose after meals; the rise in the [K+](CCD) (3.3-fold) predominated at earlier times, and the rise in flow rate occurred later and was primarily a result of a higher rate of excretion of urea. The rise in [K+](CCD) did not correlate with aldosterone levels or administration. A very large rise in the [K+](CCD) only occurred in the presence of bicarbonaturia; the transtubular potassium concentration gradient was now close to 15 in the morning and evening.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume267
Issue number2 36-2
StatePublished - Aug 30 1994

Keywords

  • aldosterone
  • bicarbonate
  • circadian rhythm
  • transtubular potassium concentration gradient
  • urea

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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