On-Line Microdialysis-Graphite Furnace Atomic Absorption Spectrometry in the Determination of Brain Magnesium Levels in Gerbils Subjected to Cerebral Ischemia/Reperfusion

Abstract

Objectives: Description of use of equipment for on-line microdialysis (MD) coupled with graphite furnace atomic absorption spectrometry (GFAAS) system, for dynamic monitoring of extracellular Mg in gerbils subjected to transient focal cerebral ischemia.

Methods: Gerbils’ right middle cerebral artery (MCA) and common carotid artery (CCA) were occluded for 60 minutes, and then reperfused for 60 minutes with Ringer’s solution, after which extracellular fluid samples were collected via a microdialysis probe inserted into the right cortex before, during and after inducing ischemia. Reperfusion was at a rate of 2 μL/min through the microdialysis probe, on-line diluted with measured water injected onto the GFAAS via an autosampler for Mg analysis.

Results: The detection limit of the Mg concentrations has ranged from 0.50 to 3.00 μg/L; our detection limit was 0.03 μg/L. We applied this on-line system to monitor extracellular Mg levels in the cortex during focal cerebral ischemia. Mg concentrations significantly decreased to 41% of baseline during cerebral ischemia and gradually returned to 67% of baseline after 60 minutes of reperfusion.

Conclusions: We presume that derangement of Mg homeostasis could be important in brain cell injury and is closely associated with cerebral ischemia event. The described analytic system permits autosampling in the brain and allows for continuous determination of Mg and trace minerals in minute sample volumes in a living system.

• cerebral ischemia
• gerbil
• magnesium
• microdialysis
• graphite furnace atomic absorption spectrometry

This study was supported by grants from Taichung Veterans General Hospital (TCVGH-917306C & 917311D) and the National Science Council (NSC-91-2113M-075A-002), Taiwan, Republic of China.