On-line microdialysis-graphite furnace atomic absorption spectrometry in the determination of brain magnesium levels in gerbils subjected to cerebral ischemia/reperfusion.
OBJECTIVE
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 microL/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 microg/L; our detection limit was 0.03 microg/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.
Department of Medical Research, Taichung Veterans General Hospital, Taichung 40705, Taiwan.
Ming-Cheng
MC
Lin
Yeou-Lih
YL
Huang
Hong-Wen
HW
Liu
Dar-Yu
DY
Yang
Chien-Pin
CP
Lee
Lin-Lan
LL
Yang
Fu-Chou
FC
Cheng
D000818:Animals; D019540:Area Under Curve; D001923:Brain Chemistry / Q000502:physiology*; D002545:Brain Ischemia / Q000378:metabolism*; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism; D004195:Disease Models, Animal; D005849:Gerbillinae; D007700:Kinetics; D008274:Magnesium / Q000032:analysis / Q000378:metabolism*; D008297:Male; D017551:Microdialysis / Q000379:methods; D015424:Reperfusion; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic / Q000379:methods
D008274:Magnesium