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Rapid astrocyte death induced by transient hypoxia, acidosis, and extracellular ion shifts
Author(s) -
Bondarenko Alexander,
Chesler Mitchell
Publication year - 2001
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.1048
Subject(s) - acidosis , hypoxia (environmental) , extracellular , intracellular ph , propidium iodide , astrocyte , programmed cell death , biology , intracellular , endocrinology , calcium , medicine , chemistry , biochemistry , apoptosis , oxygen , central nervous system , organic chemistry
Death of astrocytes requires hours to days in injury models that use hypoxia, acidosis, or calcium paradox protocols. These methods do not incorporate the shifts in extracellular K + , Na + , Cl − , and Ca 2+ that accompany acute brain insults. We studied astrocyte survival after exposure to hypoxic, acidic, ion‐shifted Ringer (HAIR), with respective [Ca 2+ ], [K + ], [Na + ], [Cl − ], and [HCO − 3 ] of 0.13, 65, 51, 75, and 13 mM (15% CO 2 /85% N 2 , pH 6.6). Intracellular pH (pH i ) was monitored with the fluorescent dye BCECF. Cell death was indicated by a steep fall in the pH‐insensitive, 440‐nm‐induced fluorescence (F440) and was confirmed by propidium iodide staining. After 15–40‐min HAIR exposure, reperfusion with standard Ringer caused death of most cultured (and acutely dissociated) astrocytes within 20 min. Cell death was not prevented if low Ca 2+ was maintained during reperfusion. Survival fell with increased HAIR duration, elevated temperature, or absence of external glucose. Comparable durations of hypoxia, acidosis, or ion shifts alone did not lead to acute cell death, while modest loss was noted when acidosis was paired with either hypoxia or ion shifts. Severe cell loss required the triad of hypoxia, acidosis, and ion shifts. Intracellular pH was significantly higher in HAIR media, compared with solutions of low pH alone or with low pH plus hypoxia. These results indicate that astrocytes can be killed rapidly by changes in the extracellular microenvironment that occur in settings of traumatic and ischemic brain injury. GLIA 34:134–142, 2001. © 2001 Wiley‐Liss, Inc.