Magnesium protects against neurological deficit after brain injury.

The biochemical factors that mediate secondary or delayed damage to the central nervous system (CNS) remain speculative. We have recently demonstrated that brain injury in rats causes a rapid decline in brain intracellular free magnesium (Mg2+) and total magnesium concentrations that is significantly correlated with the severity of injury. In order to further investigate the relationship between Mg2+ and brain injury, we examined the effect of Mg2+ treatment on posttraumatic neurological outcome following fluid-percussion brain injury (2.0 atm) in rats. Since administration of ATP-MgCl2 has been shown to be beneficial in a variety of models of organ ischemia, we also examined the efficacy of ATP-MgCl2 or ATP alone in the treatment of experimental brain injury. Animals treated with low (12.5 mumol) or high (125 mumol) dose MgCl2 at 30 min postinjury showed a significant dose-dependent improvement in neurological function when compared to saline-treated controls. Treatment with ATP-MgCl2 (12.5 mumol) or ATP alone (12.5 mumol) caused no significant improvement in chronic neurological outcome. MgCl2-treated animals showed no change in postinjury mean arterial blood pressure (MAP), whereas animals treated with either ATP-MgCl2 or ATP alone showed a transient but significant fall in MAP (P less than 0.01) during the drug-infusion period. Our results suggest that postinjury treatment with MgCl2 is effective in limiting the extent of neurological dysfunction following experimental traumatic brain injury in the rat.