Significantly decreased extracellular magnesium in brains of gerbils subjected to cerebral ischemia

Abstract

Background: A method for determining extracellular magnesium (Mg) levels in gerbil brain dialysates was developed by microdialysis and graphite furnace atomic absorption spectroscopy (GFAAS). Methods: Two microdialysis probes were inserted into the right and left cortices of a gerbil subjected to a focal cerebral ischemia. Extracellular magnesium concentrations in diluted dialysates were 1.10 and 1.12 ppb in the ipsilateral and contralateral gerbil cortex, respectively. Results: During cerebral ischemia, these concentrations decreased significantly to approximately 60% of basal in the ipsilateral cortex, whereas no changes in the contralateral cortex were detected. Extracellular magnesium concentrations returned to baseline within 3 h of reperfusion. The linearity of magnesium concentrations ranged from 0.50 to 5.0 ppb with a detection limit of 0.03 ppb in the present assay. A complete analysis can be performed within 2 min. The intra- and interassay precision was <5%. Conclusion: To our knowledge, the present method is the first analytical assay measuring dynamic extracellular magnesium concentrations during cerebral ischemia by microdialysis and graphite furnace atomic absorption spectroscopy.