Ca2+ and endonuclease activation in radiation-induced lymphoid cell death.
Exposure of lymphoid cells to X-irradiation caused an increase in cytosolic Ca2+ ([Ca2+]i) in rat thymocytes but not in rat splenocytes. The Ca2+ elevation in rat thymocytes was transitory and by 2 h postirradiation, when the chromatin degradation began to be appreciable, the [Ca2+]i had returned to control level. Inhibitors of RNA and protein syntheses prevented the radiation-induced [Ca2+]i rise in thymocytes. Pretreatment of both cell types with Ca2+ chelators also prevented DNA fragmentation, chromatin condensation, and cell death caused by X-irradiation. These data suggest that Ca2+ plays an important role in the perpetuation of apoptosis in both thymocytes and splenocytes although a Ca2+ elevation, which may serve as a signal in thymocytes, does not appear to be required to initiate radiation-induced DNA fragmentation in splenocytes.
Department of Toxicology, Karolinska Institutet, Stockholm, Sweden.
B
B
Zhivotovsky
P
P
Nicotera
G
G
Bellomo
K
K
Hanson
S
S
Orrenius
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism*; D004789:Enzyme Activation / Q000528:radiation effects; D008214:Lymphocytes / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism
C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D003609:Dactinomycin; D004533:Egtazic Acid; D003513:Cycloheximide; D004720:Endonucleases; D002118:Calcium