Biomaterial Database

Chloride/bicarbonate exchange in human erythrocytes. 1978

A Lambert, and A G Lowe

1. The exchange of chloride and bicarbonate across the human erythrocyte membrane has been followed by measuring the changes in extracellular pH which occur when chloride-rich erythrocytes are added to chloride-free media containing varying concentrations of bicarbonate and carbonic anhydrase. 2. The dependence of the rate of chloride/bicarbonate exchange on the extracellular concentration of bicarbonate was consistent with the existence of a saturable membrane anion transporter exhibiting Michaelis--Menten kinetics. In a medium containing sodium gluconate buffered to pH 7.0 with imidazole--malate the Km for bicarbonate activation of transport was 0.39 (+/- 0.03) mM and the Vmax was 2033 (+/- 80 m-mole anions exchanged/3 X 10(13) cells. min, at 10 degrees C. 3. Chloride/bicarbonate exchange was temperature-dependent with an Arrhenius activation energy of 19.4 kcal/mole in the temperature range 2--10 degrees C. 4. Exchange of intracellular chloride for extracellular bicarbonate was inhibited by the presence of extracellular halides. Inhibition by chloride, bromide and fluoride was competitive and the affinity of the transport system decreased in the order HCO-3 greater than Cl- greater than Br- greater than F-. The kinetics of inhibition by iodide were complex, but inhibitory effects of low concentrations of iodide were less than those of chloride and bromide.

UI	MeSH Term	Description	Entries
D007454	Iodides	Inorganic binary compounds of iodine or the I- ion.	Iodide
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D001965	Bromides	Salts of hydrobromic acid, HBr, with the bromine atom in the 1- oxidation state. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Bromide
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D004910	Erythrocyte Membrane	The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.	Erythrocyte Ghost,Red Cell Cytoskeleton,Red Cell Ghost,Erythrocyte Cytoskeleton,Cytoskeleton, Erythrocyte,Cytoskeleton, Red Cell,Erythrocyte Cytoskeletons,Erythrocyte Ghosts,Erythrocyte Membranes,Ghost, Erythrocyte,Ghost, Red Cell,Membrane, Erythrocyte,Red Cell Cytoskeletons,Red Cell Ghosts
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
D005459	Fluorides	Inorganic salts of hydrofluoric acid, HF, in which the fluorine atom is in the -1 oxidation state. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Sodium and stannous salts are commonly used in dentifrices.	Fluoride
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001639	Bicarbonates	Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the pH of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity.	Bicarbonate,Bicarbonate Ions,Hydrogen Carbonates,Bicarbonate Ion,Carbonic Acid Ions,Hydrogen Carbonate,Carbonate, Hydrogen,Carbonates, Hydrogen,Ion, Bicarbonate,Ions, Bicarbonate,Ions, Carbonic Acid
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill