[Effects of magnesium sulfate on brain damage by complete global brain ischemia]

The efficacy of magnesium sulfate in preventing ischemic brain damage was evaluated in 36 adult mongrel dogs subjected to an 18 min period of complete global brain ischemia. Twenty-four of 36 dogs were divided into two groups; no-therapy group (n = 12) and magnesium-treated group (n = 12). The infusion of magnesium sulfate 2.5 mmol.kg-1 was started immediately with reperfusion over 48h. In each group, acute study I and chronic study were done. In the acute study I, there were no differences between two groups in hemodynamic parameters and intracranial pressure, but delayed post-ischemic hypoperfusion was significantly improved in magnesium-treated group. In the chronic study, the neurologic outcome, which was evaluated up to 7 days after ischemia, was significantly better in magnesium-treated group than in no-therapy group. In acute study II, residual 12 dogs were divided into two groups; magnesium-administered without ischemia group (n = 6) and magnesium-administered after ischemia group (n = 6). In the acute study II, magnesium significantly crossed the blood-brain barrier into cerebrospinal fluid in magnesium-administered after ischemia group, but not in magnesium-administered without ischemia group. Magnesium might improve the neurologic outcome due to its broad and no-specific calcium entry blocking properties rather than the improvement of the delayed post-ischemic hypoperfusion. These results suggest that magnesium therapy is very useful for cerebral resuscitation after cardiac arrest.