The role of K+ influx on glutamate induced astrocyte swelling: effect of temperature

Abstract

We studied factors involved in glutamate-stimulated astrocyte swelling and the role of temperature in this process. Glutamate-induced astrocyte swelling was reduced by 74% when temperature was lowered from 37 degrees C to 24 degrees C. Reduction in temperature to 24 degrees C also resulted in inhibition of glutamate-stimulated K+ uptake. When both extracellular and intracellular Ca2+ were removed with BAP-TA/AM (50 microM) and 0.1 mM EGTA and in the absence of extracellular Ca2+, glutamate was not able to stimulate the K+ uptake or swelling. Dantrolene (20 microM), MK-801 (0.5 mM) and ouabain (0.5 mM) inhibited glutamate-induced K+ uptake as well as the glutamate effects on swelling. These findings show the importance of Ca2+ in the mechanism of glutamate swelling and suggests that glutamate induces swelling through stimulation of K+ influx and that the diminished effect of glutamate swelling with decrease in temperature may be due to a decrease in K+ uptake.