title: Further studies on alterations in magnesium binding during cold storage of erythrocytes.
abstract: Free intracellular Mg2+ concentration ([Mg2+]i) was measured in cold-stored human erythrocytes by the method of null-point titration with ionophore A23187. [Mg2+]i was 311 +/- 41 microM (mean +/- S.D.) for cells stored 0-10 days, increasing to 458 +/- 64 microM for cells stored 22-48 days. The values for stored cells were higher than those previously determined by a 31P-NMR method (Bock et al. (1985) Blood 65, 1526-1530); however, the null-point method requires extensive washing of the cells, which we have found to increase NMR-measured [Mg2+]i. The null-point values still represent a small fraction of total cell Mg2+, and confirm that binding of Mg2+ to ligands other than ATP and 2,3-bisphosphoglycerate must increase during storage. As an initial test of whether this may imply suboptimal availability of Mg2+ for cell preservation, we used A23187 to prepare erythrocytes with altered Mg2+ content, then removed ionophore and stored the cells in plasma-free medium for up to 2 weeks. Higher Mg2+ content had a very significant positive correlation (P less than 0.0001) with higher cell ATP concentrations. Storage did not significantly affect basal or Na+-stimulated efflux of Mg2+ from Mg2+-loaded red cells.
mesh_terms: D019794:2,3-Diphosphoglycerate; D000255:Adenosine Triphosphate / Q000097:blood; D001793:Blood Preservation; D000001:Calcimycin; D003080:Cold Temperature; D004163:Diphosphoglyceric Acids / Q000097:blood; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000097:blood* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy
chemical_list: D004163:Diphosphoglyceric Acids; D019794:2,3-Diphosphoglycerate; D000001:Calcimycin; D000255:Adenosine Triphosphate; D008274:Magnesium