Selective vulnerability of cultured cortical glia to injury by extracellular acidosis

Reduction of extracellular pH from 7.4 to 6.5 attenuated glutamate neurotoxicity in murine cortical neuronal and glial cultures, but if maintained for 24 h, resulted in morphological evidence of selective glial injury. Acid-induced gliotoxicity was examined quantitatively in cortical astrocyte cultures, using lactate dehydrogenase efflux as an index of cell damage. An exposure time of 9 h to pH 6.4 was sufficient to destroy about one third of the glia, whether or not 25 mM lactate was present. Furthermore, such acidosis increased the vulnerability of glia to injury by combined oxygen and glucose deprivation. These observations support the suggestion that the acidosis which accompanies ischemia in vivo may contribute to glial injury.