EFFECT OF LOW-TEMPERATURE ON GLUTAMATE-INDUCED INTRACELLULAR CALCIUM ACCUMULATION AND CELL-DEATH IN CULTURED HIPPOCAMPAL-NEURONS

To elucidate the precise mechanism of neuronal protection by brain hypothermia, we conducted an investigation as to what effect low temperature had on glutamate-induced intracellular free calcium ([Ca2+]i) accumulation and cell death in cultured hippocampal neurons. Fifteen minutes of exposure to either 100 mu M or 1 mM glutamate uniformly induced a marked increase in [Ca2+]i, with delayed recovery and massive neuronal death under the conditions of both 37 degrees C and 30 degrees C. The study indicated that brain hypothermia cannot save neurons once glutamate is released during ischemia, and that intraischemic hypothermia in vivo probably prevents the development of ischemic neuronal injury by suppressing extracellular glutamate release.