Potassium transport--an update.

Potassium homeostasis depends on the coordinated interaction between tightly regulated potassium transfer in and out of the extracellular fluid compartment, and renal excretion or retention of potassium. Potassium transport along the nephron involves extensive proximal tubule reabsorption of potassium. Potassium is also reabsorbed along the thick ascending limb of Henle's loop. Regulated potassium secretion, or potassium reabsorption in exchange for hydrogen ions along the connecting tubule and collecting tubule, is responsible for potassium excretion. Renal potassium transport is modulated by potassium intake, several hormones, acid-base factors and distal nephron sodium delivery. WNK family kinases have also emerged as factors regulating sodium and potassium transport in the distal nephron.