Shevchenko A S
National Research Institute of Agricultural Radiology and Agroecology, Russian Academy of Agricultural Sciences, Obninsk, Russia.
Izv Akad Nauk Ser Biol. 1998 Mar-Apr(2):213-9.
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.
通过5 Gy的γ射线体外诱导大鼠胸腺细胞凋亡后，测定了Ca(2+)通透性参数（在存在Ca(2+)-ATP酶阻滞剂钒酸盐的情况下Ca2+内流速率和Ca2+摄取的初始速率）。照射后30至909分钟内Ca(2+)内流速率没有变化，表明是被动膜通透性，而表征Ca(2+)交换的Ca(2+)摄取初始速率在受照射细胞中大约增加了一倍。此后，完整和受照射胸腺细胞中Ca(2+)摄取的初始速率变得相等，而受照射细胞中Ca(2+)内流速率在90至180分钟内可靠地增加了1.5至2倍。受照射胸腺细胞中Ca2+膜通透性的改变先于DNA降解的启动，并且随着凋亡的进展被动通透性受到越来越大的干扰。这些数据表明，Ca2+被动通透性和细胞内Ca2+稳态的紊乱是致死性照射胸腺细胞中的凋亡触发因素。
