[Increase in Ca(2+)-permeability of the plasma membrane during radiation-induced apoptosis of thymocytes].
The parameters of Ca(2+)-permeability (rate of Ca2+ influx in the presence of Ca(2+)-ATPase blocker vanadate and initial rate of Ca2+ uptake) were determined in the rat thymocytes after induction of apoptosis in vitro by gamma (gamma-irradiation at 5 Gy. There were no changes in the rate of Ca(2+)-influx within 30 to 909 min after irradiation, thus suggesting passive membrane permeability, while the initial rate of Ca(2+)-uptake, which characterizes Ca(2+)-exchange, approximately doubled in the irradiated cells. Thereafter, the initial rate of Ca(2+)-uptake in the intact and irradiated thymocytes became equal, while the rate of Ca(2+)-influx in the irradiated cells increased reliably 1.5-2 times within 90-180 min. Modification of membrane permeability for Ca2+ in the irradiated thymocytes precedes initiation of DNA degradation, and passive permeability is increasingly disturbed as apoptosis progresses. These data suggest that disturbances in Ca2+ passive permeability and intracellular Ca2+ homeostasis are an apoptosis trigger in lethally irradiated thymocytes.
Shevchenko
A S
AS
National Research Institute of Agricultural Radiology and Agroecology, Russian Academy of Agricultural Sciences, Obninsk, Russia.
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D001692:Biological Transport / Q000528:radiation effects; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002463:Cell Membrane Permeability / Q000528:radiation effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005720:Gamma Rays; D006706:Homeostasis; D066298:In Vitro Techniques; D007700:Kinetics; D008214:Lymphocytes / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D051381:Rats; D013950:Thymus Gland / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D014638:Vanadates / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014638:Vanadates; D000252:Calcium-Transporting ATPases; D002118:Calcium
Uvelichenie pronitsaemosti plazmaticheskoĭ membrany dlia Ca(2+) pri radiatsionno-indutsirovannom apoptoze timotsitov.