title: Studies on the mechanism of decreased NMR-measured free magnesium in stored erythrocytes.
abstract: 31P-NMR spectra have been recorded on erythrocytes stored at 4 degrees C in various preservation media. Storage was always associated with an upfield shift of the inorganic phosphate (Pi) resonance and a pronounced upfield shift of the ATP beta resonance, indicating decreased intracellular pH (pHi) and decreased intracellular free magnesium ([Mg2+]i). The decreased [Mg2+]i occurred in preservation media not containing citrate and even in media supplemented with Mg2+. It could not be attributed to the changes in pHi, Na+, K+, lactate, Pi or 2,3-diphosphoglycerate, that occur with storage. The decrease in [Mg2+]i was largely reversed when stored cells were incubated for 1 h at 37 degrees C in fresh plasma. Stored cells were found to contain significant amounts of inorganic pyrophosphate, up to about 200 mumol per liter cell water. Being a tight binder of Mg2+, pyrophosphate could account for some of the observed decrease in [Mg2+]i. Additional mechanisms may involve precipitation of some other Mg2+ complex during cold storage or enhancement of Mg2+ binding to membrane components.
mesh_terms: D001793:Blood Preservation / Q000379:methods*; D011756:Diphosphates / Q000097:blood; D004912:Erythrocytes / Q000032:analysis*; D006801:Humans; D008274:Magnesium / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy; D013997:Time Factors
chemical_list: D011756:Diphosphates; D008274:Magnesium