CALCULATION OF INTRACELLULAR CEREBRAL [MG2-VIVO P-31 NMR(] DURING HYPOXIC ISCHEMIA BY IN)

SEVERAL algorithms for the calculation of ionized intracellular magnes ium concentration from the chemical shifts of MgATP were compared, usi ng in vivo P-31 NMR data obtained from swine brain during and followin g hypoxic ischemia plus i.v. MgSO4 infusion. This analysis reveals tha t both the absolute ionized intracellular magnesium and relative chang es in magnesium may vary widely between algorithms used. The calculate d intracellular pH, used in algorithms to determine ionized magnesium concentration was found to be a critical parameter that governs the ex tent of these differences.