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A method for estimating free Ca within human red blood cells, with an application to the study of their Ca-dependent K permeability. 1982

T J Simons

Murphy, Coll, Rich and Williamson (J. Biol. Chem. 255:6600--6608, 1980) described a null-point method for estimating intracellular free Ca in liver cells. They used digitonin to lyse the cells in solutions of varying Ca concentration. This method has been adapted for use with human red cells. The values found are about 0.4 micron or micrometer Ca in fresh cells, and from 0.4 to 0.7 micron or micrometer Ca in blood-bank cells, at pH 7.2 and 37 degrees C. These are likely to be overestimates, and the errors and limitations of the method are discussed. Red cells may be loaded with Ca by metabolic depletion in Ca-containing solutions. Such cells have an elevated K permeability, and the relationships between free Ca, total Ca and K permeability were investigated, using 86Rb as a tracer for K. 86Rb flux studies show that the affinity of the K channel for Ca is the same in cells as in resealed ghosts where intracellular Ca can be controlled with Ca buffers, but the rate of tracer equilibration is 3-6 times faster in ghosts than in cells.

UI MeSH Term Description Entries
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.
D008722 Methods A series of steps taken in order to conduct research. Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
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.
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002463 Cell Membrane Permeability A quality of cell membranes which permits the passage of solvents and solutes into and out of cells. Permeability, Cell Membrane
D004905 Erythrocyte Aging The senescence of RED BLOOD CELLS. Lacking the organelles that make protein synthesis possible, the mature erythrocyte is incapable of self-repair, reproduction, and carrying out certain functions performed by other cells. This limits the average life span of an erythrocyte to 120 days. Erythrocyte Survival,Aging, Erythrocyte,Survival, Erythrocyte
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
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
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

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