Neuroprotective effects of MgSO4 and MgCl2 in closed head injury: a comparative phosphorus NMR study.

Previous studies have shown that free magnesium levels decline after traumatic brain injury and that magnesium salt administration improves posttraumatic outcome. These earlier studies, however, have been limited to models of injury that do not produce a significant degree of diffuse axonal injury and have used either MgSO4 or MgCl2 as the magnesium salt. The present study compares the neuroprotective efficacy of MgSO4 and MgCl2 in a severe model of diffuse axonal injury in rats using phosphorus nuclear magnetic resonance spectroscopy and the rotarod test to monitor effects on metabolism and neurologic outcome, respectively. Both MgSO4 and MgCl2 given as a bolus of 100 micromoles/kg at 30 min after severe, closed head injury significantly improved brain intracellular free magnesium concentration and neurologic outcome. These findings suggest that both salts penetrate the blood-brain barrier after brain trauma, enter injured tissue, and subsequently improve neurologic outcome.