Renal potassium transport: morphological and functional adaptations

Am J Physiol. 1989 Nov;257(5 Pt 2):R989-97. doi: 10.1152/ajpregu.1989.257.5.R989.

Abstract

Maintenance of K+ homeostasis in mammals and amphibians depends primarily on the kidneys which excrete 95% of K+ ingested in the diet. The amount of K+ in the urine is determined by the rate of K+ secretion or absorption by the distal tubule and the collecting duct. When K+ intake is increased, K+ secretion rises. The mechanisms of K+ secretion by the distal tubule and collecting duct are so efficient that K+ intake can increase 20-fold with little or no increase in body K+ content or in plasma K+ concentration. Elevated K+ secretion by the distal tubule and collecting duct occurs in part because of an increase in the quantity of Na+-K+-adenosinetriphosphatase (Na+-K+-ATPase) and amplification of the basolateral membrane of principal cells. When dietary K+ intake is reduced, urinary K+ excretion falls, because K+ secretory mechanisms are suppressed and K+ absorptive mechanisms, residing in the distal tubule and collecting duct, are activated. Because a low-K+ diet is associated with hypertrophy of intercalated cells, it has been suggested that this cell type absorbs K+, possibly by an H+-K+-ATPase. In this review, I discuss the functional and morphological evidence that supports the view that principal cells secrete K+ and that intercalated cells absorb K+. In addition, some of the hormones and factors that are responsible for these changes in cell structure and function are discussed.

Publication types

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

MeSH terms

  • Adaptation, Physiological*
  • Animals
  • Biological Transport
  • Biomechanical Phenomena
  • Diet
  • Kidney / metabolism*
  • Kidney / physiology
  • Kidney / ultrastructure
  • Kidney Tubules, Collecting / ultrastructure
  • Kidney Tubules, Distal / ultrastructure
  • Potassium / metabolism*
  • Potassium / pharmacology
  • Potassium / urine

Substances

  • Potassium