Challenges to potassium metabolism: internal distribution and external balance.
A complex pump-leak system involving both active and passive transport mechanisms is responsible for the appropriate distribution of potassium (K) between the intra- and extracellular fluid compartments. In addition, the kidneys, and to a lesser extent the colon, safeguard maintenance of the narrow range of low K concentrations in the extracellular fluid. Early renal clearance studies showed that K is normally both reabsorbed and secreted by renal tubules, and that regulated secretion is the major source of K excretion. Net K secretion occurs mainly in principal cells while K absorption takes place in intercalated cells. Studies on single tubules and principal and intercalated cells have defined the determinants of K secretion and reabsorption including the electrochemical driving forces, specific carriers, ATPases, and K channels. Recent studies on the properties and molecular identity of renal K channels have also contributed significantly to understanding the renal mechanisms that transport and regulate K excretion.
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, USA. Gerhard.giebisch@yale.edu
Gerhard
G
Giebisch
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D011188:Potassium / Q000737:chemistry* / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000502:physiology*; D014018:Tissue Distribution
D015221:Potassium Channels; D011188:Potassium