Regulation of Astroglial Volume by Ketamine in Glutamate Induced Cellular Volume Changes

Kim, Myung Hee; Hahm, Tae Soo; Ahn, Hyun Joo

Abstract

BACKGROUND
Relative changes of astroglial volume constitute the major part of brain edema, which is related to delayed neuronal damage. Several factors including glutamate may contribute to astroglial swelling. Intravenous anesthetic, ketamine was known to restore neuronal damage by inhibiting NMDA receptor activity. Therefore, we decided to investigate the effect of ketamine on the astrocyte swelling by glutamate in the present study.
METHODS
To analyze cell swelling in vitro, glial cell line, U1242MG was used. The effects of glutamate (1, 2, 3 mM), and glutamate with ketamine (1 mM) on the regulation of astrocyte volume were achieved by flow cytometry system. To eliminate the dead cells from experimental cell suspension and to assess cell viability, fluorescent dye propidium iodide was used.
RESULTS
Glutamate addition (1, 2, 3mM) caused astroglial swelling both in calcium present and calcium absent buffer. The difference of cellular swelling dependent on glutamate concentration was only seen in calcium free buffer (p<0.05). Ketamine per se did not affect astroglial volume. However, when it was added to glutamate perfusion, 1 mM ketamine diminished cellular swelling by glutamate during first 10 minutes (p<0.05), and cellular shrinkage by glutamate after 1 hour incubation (p<0.05).
CONCLUSIONS
Ketamine (1 mM) is effective in the regulation of astroglial volume alterations induced by glutamate in both short time and long time perfusion.