NA+/K+ ATPase

(noun)

An ATPase pump that consumes ATP to facilitate the active transport of ions in filtrate of the nephron.

Related Terms

Examples of NA+/K+ ATPase in the following topics:

  • Body Fluid Composition

    • The reason for these specific sodium and potassium ion concentrations are Na+/K ATPase pumps, which facilitate the active transport of these ions.
    • The cations include: sodium (Na+ = 136-145 mEq/L), potassium (K+ = 3.5-5.5 mEq/L) and calcium (Ca2+ = 8.4-10.5 mEq/L).
    • Plasma is mostly water (93% by volume) and contains dissolved proteins (major proteins are fibrinogens, globulins and albumins), glucose, clotting factors, mineral ions (Na+, Ca++, Mg++, HCO3- Cl- etc.), hormones and carbon dioxide (plasma being the main medium for excretory product transportation).

  • Tubular Reabsorption

    • Active transport—membrane-bound ATPase pumps (such as NA+/K+ ATPase pumps) with carrier proteins that carry substances across the plasma membranes of the kidney epithelial cells by consuming ATP.

  • Regulation of Water Output

    • It acts on mineralcorticoid receptors in the epithelial cells of the distal convoluted tubule and collecting duct, which increases their expression of Na+/K+ ATPase pumps and activates those pumps.

  • Nephron, Parts, and Histology

    • Water reabsorption in the proximal convoluted tubule occurs due to both passive diffusion across the basolateral membrane, and active transport from Na+/K+/ATPase pumps that actively transports sodium across the basolateral membrane.

  • Tubular Secretion

    • Active transport—the movement of molecules via ATPase pumps that transport the substance through the renal epithelial cell into the lumen of the nephron.
    • The movement of these ions also helps to conserve sodium bicarbonate (NaHCO3).

  • Potassium Balance Regulation

    • Cell K+ concentration is about 150 mmol/l but varies in different organs.
    • It is present as an organic salt while sodium is added as NaCl.
    • Processing of foods replaces K+ with NaCl.
    • While the body can excrete a large K+ load it is unable to conserve K+.
    • On a zero K+ intake or in a person with K+ depletion there will still be a loss of K+ of 30-50 mmol/d in the urine and feces.

  • Sodium Balance Regulation

    • The body has potent sodium retaining mechanisms and even if a person is on five mmol Na+/day they can maintain sodium balance.
    • A high plasma potassium also increases aldosterone secretion because besides retaining Na+ high plasma aldosterone causes K+ loss by the kidney.
    • Plasma Na+ levels have little effect on aldosterone secretion.
    • This immediately causes release of ADH which causes water to be retained, thus retaining Na+ and H2O in the right proportion to restore plasma volume.
    • Elevated blood pressure will also tend to cause Na+ loss and a low blood pressure usually leads to sodium retention.

  • Resting Membrane Potentials

    • R is the universal gas constant, equal to 8.314 joules·K−1·mol−1.
    • T is the absolute temperature measured in kelvins (= K = degrees Celsius + 273.15).
    • The three ions that appear in this equation are potassium (K+), sodium (Na+), and chloride (Cl−).
    • Goldman equation: R is the universal gas constant, equal to 8.314 joules·K−1·mol−1 T is the absolute temperature, measured in kelvins (= K = degrees Celsius + 273.15) F is the Faraday constant, equal to 96,485 coulombs·mol−1 or J·V−1·mol−1

  • Ionotropic and Metabotropic Receptors

    • Ionotropic receptors are a group of transmembrane ion channels that open or close in response to the binding of a chemical messenger (ligand) such as a neurotransmitter.The binding site of endogenous ligands on LGICs protein complexes are normally located on a different portion of the protein (an allosteric binding site) than the location of the ion conduction pore.The ion channel is regulated by a ligand and is usually very selective to one or more ions such as Na+, K+, Ca2+, or Cl-.
    • This pore allows Na+ ions to flow down their electrochemical gradient into the cell.
    • With a sufficient number of channels opening at once, the inward flow of positive charges carried by Na+ ions depolarizes the postsynaptic membrane enough to initiate an action potential.

  • Principles of Electricity

    • Many ions have a concentration gradient across the membrane, including potassium (K+), which is at a high inside and a low concentration outside the membrane.
    • Sodium (Na+) and chloride (Cl–) ions are at high concentrations in the extracellular region and low concentrations in the intracellular regions.