Biomaterial Database

K-Cl cotransport, pH, and role of Mg in volume-clamped low-K sheep erythrocytes: three equilibrium states. 1994

P K Lauf, and A Erdmann, and N C Adragna

Department of Physiology and Biophysics, Wright State University, Dayton, Ohio 45435.

Ouabain-resistant K efflux and Rb influx in Cl and NO3 media were studied in volume-clamped low-K (LK) sheep red blood cells (SRBC) with normal and experimentally reduced cytoplasmic Mg (Mgi) levels as function of pH and at 37 degrees C. Sucrose was added to solutions with constant ionic strength and variable pH to maintain normal cell volume. Cl-dependent ouabain-resistant K(Rb) fluxes (K-Cl cotransport) at unity relative cell volume exhibited a maximum at pH approximately 7 in normal-Mgi LK cells consistent with the apparent acid pH activation reported for human erythrocytes. However, in LK SRBC with Mgi lowered by A-23187 and an external Mg chelator, K(Rb)-Cl cotransport was reversibly activated as the pH was raised from 6.5 to 9. The alkaline pH effect on Cl-dependent Rb influx in low-Mgi LK SRBC was due to a 10-fold rise in the maximum velocity values without a major change in the Km values. The pH dependence of the experimental flux reversal point, i.e., the extracellular Rb concentration at which no net K-Cl cotransport occurs, approximately paralleled that of the flux reversal point predicted from the ratio of the ion products, in both control and low-Mgi LK cells, albeit with a small displacement to higher extracellular Rb concentration at all pH values. The kinetic data can be explained by a general minimum three-state equilibrium in which deprotonation recruits transporters from a resting R state into the active A state modified by Mgi to an inactive I state.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D009566	Nitrates	Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.	Nitrate
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.
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D003470	Culture Media	Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.	Media, Culture
D004912	Erythrocytes	Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.	Blood Cells, Red,Blood Corpuscles, Red,Red Blood Cells,Red Blood Corpuscles,Blood Cell, Red,Blood Corpuscle, Red,Erythrocyte,Red Blood Cell,Red Blood Corpuscle
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000096922	K Cl- Cotransporters	A subclass of symporters that specifically transport POTASSIUM and CHLORIDE ions across cellular membranes. Potassium chloride cotransporters play roles in regulating cell volume and intracellular chloride concentration.	Electroneutral Potassium-Chloride Co-transporter 3,Electroneutral Potassium-Chloride Cotransporter 3,K Cl- Co-transporters,K(+), Cl(-)-Co-transporters,K(+), Cl(-)-Cotransporters,K-Cl Co-transporter,K-Cl Co-transporter 3,K-Cl Cotransporter,K-Cl Cotransporter 3,KCC2 Co-transporter,KCC2 Cotransporter,KCC3 Co-transporter,KCC3 Cotransporter,KCC4 Co-transporter,KCC4 Cotransporter,Potassium-Chloride Co-transporter 2,Potassium-Chloride Co-transporter 4,Potassium-Chloride Co-transporters,Potassium-Chloride Cotransporter 2,Potassium-Chloride Cotransporter 4,Potassium-Chloride Cotransporters,Potassium-Chloride Symporters,SLC12A5 Protein,SLC12A6 Protein,SLC12A7 Protein,Solute Carrier Family 12 Member 5,Solute Carrier Family 12 Member 6,Solute carrier family 12 member 7,Cl- Co-transporters, K,Co-transporter 2, Potassium-Chloride,Co-transporter 3, K-Cl,Co-transporter 4, Potassium-Chloride,Co-transporter, K-Cl,Co-transporter, KCC2,Co-transporter, KCC3,Co-transporter, KCC4,Co-transporters, K Cl-,Co-transporters, Potassium-Chloride,Cotransporter, K-Cl,Cotransporter, KCC2,Cotransporter, KCC3,Cotransporter, KCC4,Cotransporters, K Cl-,Cotransporters, Potassium-Chloride,Electroneutral Potassium Chloride Co transporter 3,Electroneutral Potassium Chloride Cotransporter 3,K Cl Co transporter,K Cl Co transporter 3,K Cl Co transporters,K Cl Cotransporter,K Cl Cotransporter 3,K Cl Cotransporters,KCC2 Co transporter,KCC3 Co transporter,KCC4 Co transporter,Potassium Chloride Co transporter 2,Potassium Chloride Co transporter 4,Potassium Chloride Co transporters,Potassium Chloride Cotransporter 2,Potassium Chloride Cotransporter 4,Potassium Chloride Cotransporters,Potassium Chloride Symporters,Protein, SLC12A5,Protein, SLC12A6,Protein, SLC12A7