| 11 th Annual Pediatric Critical Care Colloquium |
| Session/Time | Neurology/Fri, 10:00 - 12:00 PM |
| Title | Increase Expression of Na-K-2CI Cotransporter Expression Following Global Brain Ischemia |
| Author | MF Karadsheh, J Lu, R England, J Barwise, E Delpire |
| Affiliation | Departments of Pediatrics and Anesthesiology, Vanderbilt Medical Center, Nashville, Tennessee |
| Introduction | r-aminobutyric acid (GADA), the major inhibitory neurotransrnitter in the adult nervous system, acts through intrinsic Cl- channels. Regulation of intracellular Cl- by electroneutral cation-chloride cotransporters, i.e. Na-K-2CI cotransporter, in GABAergic neurons has profound implications in brain physiology and pathophysiology. Previous studies have suggested that Na-K-2Cl contransporter expression is developmentally regulated in postnatal rat brains. Na-K-2Cl contransporter expression correlates with the GABA effect: high in immature brain where GABA is excitatory and low in mature brain where GABA is inhibitory. Since injured neurons behave as immature neurons under GABA we examined the efffect of brain injury on the expression of the contransproter. |
| Method | Global ischemia was induced in 6 adult male Spra-ue-Dawley rats and the level of Na-K-2CI cotransporter expression was compared to the level of expression in 5 sham- operated animals. Ischemia was induced by exposing and occluding the 2 common carotids for 12 minutes. Electroencephalogram (EEG) was recorded during ischemia to confirm decrease in brain activity (flat EEG). Blood pressure was monitored durinc, the entire procedure. The rats were then sterilely sutured and sacrificed after 24 hours. 'The rats were perfused and fixed with 4% paraformaldehyde and the brains were cryoprotected with sucrose. Seven um sections were stained with anti-Na-K-2Cl cotransporter polvclonal'body and the expression measured by immunogluorescence in the hippocampus. |
| Result | Ischemic injury induced a significant increase in Na-K- 2CI cotransporter expression in the CAI recion but not CA3 nor dentate gyrus, as compared to controls |
| Conclusion | These results are consistent With Previous reports slio%vinc, that the CAI region is more sensitive to ischemic injury, and consistent with our hypothesis that the Na-K-2CI cotransporter is involved in depolarizing GABA responses.<3, |
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