Calcium Dynamics in Astrocytes During Cell Injury

The changes in intracellular calcium concentration ([Ca(2+)]) following laser-induced cell injury in nearby cells were studied in primary mouse astrocytes selectively expressing the Ca(2+) sensitive GFAP-Cre Salsa6f fluorescent tandem protein, in an Ast1 astrocyte cell line, and in primary mouse astrocytes loaded with Fluo4. Astrocytes in these three systems exhibit distinct changes in [Ca(2+)] following induced death of nearby cells. Changes in [Ca(2+)] appear to result from release of Ca(2+) from intracellular organelles, as opposed to influx from the external medium. Salsa6f expressing astrocytes displayed dynamic Ca(2+) changes throughout the phagocytic response, including lamellae protrusion, cytosolic signaling during vesicle formation, vesicle maturation, and vesicle tract formation. Our results demonstrate local changes in [Ca(2+)] are involved in the process of phagocytosis in astrocytes responding to cell corpses and/or debris.