Hypermagnesemia does not increase brain intracellular magnesium in newbornswine

Phosphorus-31 magnetic resonance spectroscopy was used in 2-day (n = 4) and 40-day (n = 4) miniswine to determine whether plasma hypermagnesemia alter s brain intracellular magnesium concentration and if the plasma-brain intra cellular magnesium relationship changes with age. At control, brain intrace llular magnesium concentration was similar in the 2-day (0.24 +/- 0.04 mM) and 40-day groups (0.21 +/- 0.01 mM). Intravenous infusions of magnesium su lfate (MgSO4, 60 minute) raised plasma magnesium concentration to 4-6 mM in both groups. During and for 3 hours after MgSO4 infusions, there were no c hanges in brain intracellular magnesium concentration in either group and n o correlation between plasma and brain intracellular magnesium (r = 0.11 an d 0.08 for 2- and 40-day groups, respectively). Brain intracellular magnesi um concentration appears to be tightly regulated. (C) 2001 by Elsevier Scie nce Inc. All rights reserved.