title: Buffering and activity coefficient of intracellular free magnesium concentration in human erythrocytes.
abstract: Human erythrocytes either untreated or Mg2+(-)loaded by means of A23187 in the presence of 3 or 12 mM MgCl2 were haemolysed by freezing and thawing. In the haemolysates the concentration of total Mg2+ (by atomic absorption spectrophotometry), free Mg2+ (by a Mg2+(-)sensitive electrode) and ATP were determined. The increase in the free Mg2+ concentration was also measured when titrating the haemolysates with MgCl2. The experiments yielded a total Mg2+ buffer capacity of 4.85mM with a Ka of 0.9 mM-1, indicating that 2,3 bisphosphoglycerate was the main Mg2+ buffer in haemolysates of erythrocytes which had been ATP-depleted during preparation. The activity coefficient of free Mg2+ in erythrocytes was the same as in the chloride-based calibration solutions.
authors.affiliation: Institute of Molecular Biology and Biochemistry, Free University of Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Günther
authors.forename: J
authors.initials: J
authors.lastname: Vormann
authors.forename: J A
authors.initials: JA
authors.lastname: McGuigan
mesh_terms: D002021:Buffers; D000001:Calcimycin / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D016014:Linear Models; D008274:Magnesium / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy; D010758:Phosphorus
chemical_list: D002021:Buffers; D010758:Phosphorus; D000001:Calcimycin; D008274:Magnesium