Control of astrocyte volume by intracellular and extracellular Ca2+.
Astrocytes from primary culture were exposed to conditions that affect intracellular and extracellular Ca2+ concentrations. Astrocyte cell volume was increased approximately 16% after a 30 min exposure to isoosmotic phosphate-buffered saline (PBS) containing the Ca2+ buffer EDTA. Cell volume returned to control values within 30 min of resuspension in normal PBS. Cellular calcium content was not affected by these treatments; however, the recovery of normal cell volume following EDTA exposure was inhibited by 0.1-1.0 mM quinine HCl in a dose-dependent fashion suggesting that a potassium channel controlled by the intracellular Ca2+ concentration is important in this volume response. Intracellular accumulation of an exogenous Ca2+ buffer, BAPTA, also produced cell swelling that persisted following resuspension in normal PBS. Lowering the extracellular Ca2+ concentration with EDTA enhanced the swelling of BAPTA-loaded cells. These data suggest that conditions leading to a decrease in free intracellular Ca2+ concentration may influence astrocyte volume by a mechanism similar to that described in other cell types.
Olson
J E
JE
Department of Emergency Medicine, Wright State University School of Medicine, Dayton, Ohio 45401.
Fleischhacker
D
D
Murray
W B
WB
Holtzman
D
D
D000818:Animals; D001253:Astrocytes / Q000166:cytology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000378:metabolism / Q000494:pharmacology / Q000031:analogs & derivatives; D005110:Extracellular Space / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism*; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains
D000001:Calcimycin; D004533:Egtazic Acid; D004492:Edetic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium