[Increased plasma membrane permeability for Ca2+ in radiation-induced thymocyte apoptosis].
Parameters of the Ca2+ permeability (the 45Ca influx rate in the presence of orthovanadate blocking the Ca(2+)-ATPhase, and the initial rate of the 45Ca uptake) and the DNA fragmentation were determined in rat thymocytes after gamma-irradiation-induced (with a dose of 5 Gy) apoptosis. Within the first 30-90 min after irradiation, the 45Ca influx rate that is characteristic of the membrane passive permeability remained unchanged. The initial rate of the 45Ca uptake that is characteristic of the Ca2+ exchange almost doubled. In 90-180 min, the rate of the 45Ca influx in the irradiated cells increased 1.5 to 2.0 times. An increase in the DNA fragmentation was observed in 90-120 min after irradiation of thymocytes; in 3 h, it developed up to 50%. Thus, modification of the membrane Ca2+ permeability in the irradiated thymocytes precedes a stage of initiation of the DNA degradation. A degree of disturbance of the membrane passive permeability increases as the thymocyte apoptosis progresses. The obtained data suggest that disturbance of the passive Ca2+ permeability and the intracellular Ca2+ homeostasis are responsible for the apoptosis of lethally irradiated thymocytes.
Shevchenko
A S
AS
Gabaĭ
V L
VL
Kobialko
V O
VO
Makarova
Iu M
IuM
Shevchenko
T S
TS
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors / Q000528:radiation effects; D002122:Calcium Chloride / Q000493:pharmacokinetics / Q000528:radiation effects*; D002132:Calcium Radioisotopes; D002463:Cell Membrane Permeability / Q000528:radiation effects*; D002478:Cells, Cultured; D004247:DNA / Q000528:radiation effects; D053938:DNA Fragmentation / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005720:Gamma Rays; D051381:Rats; D013950:Thymus Gland / Q000166:cytology / Q000528:radiation effects*; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology
D002132:Calcium Radioisotopes; D004791:Enzyme Inhibitors; D014638:Vanadates; D004247:DNA; D017301:Ca(2+) Mg(2+)-ATPase; D002122:Calcium Chloride