title: Intra- and extraerythrocyte pH at 37 degrees C and during long term storage at 4 degrees C: 31P NMR measurements and an electrochemical model of the system.
abstract: A 31P NMR method based on pH dependent variation of the chemical-shift-difference between the resonances of orthophosphate and methylphosphonate was used to measure simultaneously intracellular pH (pHi) and extracellular pH (pHc) during long term storage of erythrocytes; pH was determined at both 4 degrees C and 37 degrees C. An equation describing the equilibrium distribution of membrane-permeant ions was derived by consideration of the electrochemical and osmotic constraints in the RBC suspension. Calculations using the model-equation and the measured pHi yielded the Donnan ratio and therefore pHo; the relationship between experimentally determined pHi and pHo values was accurately predicted by the model. Sensitivity analysis of the model-equation revealed that the observed increase in transmembrane pH gradient during storage is principally due to the alteration of the total net charge of intracellular (poly)-anions.
mesh_terms: D019794:2,3-Diphosphoglycerate; D000255:Adenosine Triphosphate / Q000378:metabolism; D001793:Blood Preservation; D004163:Diphosphoglyceric Acids / Q000378:metabolism; D004912:Erythrocytes / Q000032:analysis* / Q000166:cytology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008433:Mathematics; D010761:Phosphorus Radioisotopes; D013696:Temperature
chemical_list: D004163:Diphosphoglyceric Acids; D007773:Lactates; D010761:Phosphorus Radioisotopes; D019794:2,3-Diphosphoglycerate; D000255:Adenosine Triphosphate