Magnesium sulphate reduces cell volume in physiological conditions but not in the cytotoxic oedema during global brain ischemia

Abstract

Primary objective: To establish the effect of MgSO4on brain cellular volume during physiological and global ischemia using impedanciometric method.Research design: Impedanciometric measure in the brain before and during global brain ischemia, with or without intravenous infusion of MgSO4.Methods and procedures: Male Sprague-Dawley rats were anaesthetized (thiobarbital, 60 mg kg−1 i.p.). Ringer solution (n = 9) or MgSO4(n = 8; 1 mmol Kg−1) where i.v. isovolumetrically administered. Sub-cortical impedance was recorded before and after the infusion of ringer or MgSO4and during global cerebral ischemia induced by a cardiopulmonary arrest.Main outcomes and results: In non-ischemic conditions, MgSO4infusion induced higher voltage values than those of ringer infusion (Wilcoxon, Z = 2.49; p = 0.01). During global cerebral ischemia, the MgSO4infused animals showed a fast drop of voltages (82%) in the first 5 minutes, 4-fold the values of ringer infused animals (p < 0.0001). In the following 15 minutes no differences were found between ringer and MgSO4infused animals.Conclusions: The results suggest that MgSO4significantly reduced brain cell volume in physiological conditions but not in global brain ischemia