RYANODINE-INDUCED INTRACELLULAR CALCIUM MOBILIZATION IN CULTURED ASTROCYTES

Changes in intracellular Ca2+ concentration were monitored in cultured cortical astrocytes challenged with ryanodine and ATP. Ryanodine elic ited a modest, in comparison to ATP, increase in cytosolic Ca2+ concen tration in approximately 60% of the cell fields examined. This effect was evident and, in fact, was augmented when incubations were performe d in Ca2+-free bathing medium. In addition, ryanodine-evoked changes i n intracellular Ca2+ concentration were dose dependent, desensitised r apidly, and could not be mimicked by caffeine. Exposure to ryanodine w as without effect on eicosanoid release from these cells nor did it in fluence Ca2+ mobilisation and eicosanoid release in response to ATP. I n contrast, caffeine attenuated part of the ATP-evoked increase in int racellular Ca2+ concentration in the majority of cells tested and abol ished its effect on eicosanoid release. (C) 1994 Wiley-Liss, Inc.