Biomaterial Database

Cellular pathways of potassium transport in renal inner medullary collecting duct. 1989

B C Kone, and D Kikeri, and M L Zeidel, and S R Gullans

Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston 02115.

The dominant K+ transport pathways in rabbit inner medullary collecting duct (IMCD) cells were identified using an extracellular K+ electrode and fluorometric estimates of membrane potential. Ba2+ (5 mM) caused an initial rate of net K+ influx (61 +/- 6 nmol K+.min-1. mg protein-1) equivalent to the net K+ efflux (59 +/- 5 nmol K+. min-1.mg protein-1) induced by ouabain (0.1 mM). Addition of ouabain to Ba2+ -treated cells caused no net K+ flux. Membrane potential experiments demonstrated a K+ conductance that was inhibited by Ba2+. Thus K+ transport in the IMCD occurs principally via Ba2+ -sensitive K+ conductive pathway(s) and Na+-K+-ATPase. In studies that examine the metabolic determinants of K+ transport in the IMCD, glucose (but not 3-O-methylglucose) augmented oxygen consumption (QO2; + 12%) and cell K+ content (+12%), whereas iodoacetic acid, an inhibitor of glycolysis, promoted a release of cell K+. However, inhibition of mitochondrial oxidative phosphorylation with rotenone demonstrated that glycolysis alone could not maintain cell K+ content. Thus glucose metabolism plays an important role in K+ transport in the IMCD, but both glycolysis and oxidative phosphorylation are required to maintain optimal cellular K+ gradients.

UI	MeSH Term	Description	Entries
D007461	Iodoacetates	Iodinated derivatives of acetic acid. Iodoacetates are commonly used as alkylating sulfhydryl reagents and enzyme inhibitors in biochemical research.	Iodoacetic Acids,Acids, Iodoacetic
D007684	Kidney Tubules	Long convoluted tubules in the nephrons. They collect filtrate from blood passing through the KIDNEY GLOMERULUS and process this filtrate into URINE. Each renal tubule consists of a BOWMAN CAPSULE; PROXIMAL KIDNEY TUBULE; LOOP OF HENLE; DISTAL KIDNEY TUBULE; and KIDNEY COLLECTING DUCT leading to the central cavity of the kidney (KIDNEY PELVIS) that connects to the URETER.	Kidney Tubule,Tubule, Kidney,Tubules, Kidney
D007685	Kidney Tubules, Collecting	Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla.	Kidney Collecting Ducts,Kidney Collecting Duct,Collecting Duct, Kidney,Collecting Ducts, Kidney
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008757	Methylglucosides		Methylglucopyranosides
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
D010085	Oxidative Phosphorylation	Electron transfer through the cytochrome system liberating free energy which is transformed into high-energy phosphate bonds.	Phosphorylation, Oxidative,Oxidative Phosphorylations,Phosphorylations, Oxidative
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.