Traumatic spinal cord injury in rabbits decreases intracellular free magnesium concentration as measured by 31P MRS

Abstract

The mechanisms by which traumatic injury to the central nervous system cause irreversible tissue damage remain speculative. Recent reports suggest that a decrease in tissue total and free Mg 2+ concentration may be an important factor in the development of such injury after experimental brain trauma. Although total Mg changes have been reproted following spinal cord trauma, no studies have examined spinal cord-free Mg 2+. In the present study, we have used phosphorus magnetic resonance spectroscopy to determine intracellular free Mg 2+ concentration and atomic absorption spectrophotometry to measure total tissue Mg concentration in rabbit spinal cord prior to and following impact trauma. We report that intracellular free Mg 2+ concentration decreases from a pre-injury value of 0.80 ± 0.12m M (mean ±S.E.M.) to 0.31 ± 0.05m M at 2 h post-trauma. Following injury there was a associated decrease in total tissue Mg and K concentration, but no alterations in tissue Na or water content.