PMID: 8613811Jan 1, 1996Paper

In vitro ischemia promotes calcium influx and intracellular calcium release in hippocampal astrocytes

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
S Duffy, B A MacVicar

Abstract

The intracellular calcium concentration ([Ca2+])i of astrocytes within rat hippocampal slices was measured during simultaneous hypoxia and hypoglycemia to examine the early intracellular signaling events induced by this in vitro model of ischemia. Hypoxia-hypoglycemia for 3.3-7.5 min evoked [Ca2+]i increases in astrocytes iontophoretically loaded with calcium orange (11/14 slices; 2.5 min to peak [Ca2+]i, 5 min to > 60 min duration). Calcium elevations also were observed in the absence of extracellular calcium ([Ca2+]o) (4/4 slices), indicative of Ca2+ release from internal stores. Hypoxia-hypoglycemia depolarized astrocytes (51 +/- 16 mV), suggesting additional contribution from voltage-gated Ca2+ influx. Depolarization of a similar magnitude (51 +/- 4 mV) by 50 mM extracellular potassium ([K+]o triggered [Ca2+]i increases (20/24 slices), which were blocked by removal of [Ca2+]o (8/8 slices) indicating that depolarization promoted Ca2+ influx. Voltage-gated Ca2+ influx and internal release were measured in accurately isolated astrocytes during in vitro ischemia to examine these processes in the absence of surrounding neurons. Hypoxia-hypoglycemia (7.5-34.0 min) induced only modest, slow increases in the basal [Ca2+]i of Fura-2...Continue Reading

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