Santini M T, Cametti C, Straface E, Indovina P L
Laboratorio di Ultrastrutture, Istituto Superiore di Sanità, Rome, Italy.
Int J Radiat Biol. 1993 Jan;63(1):21-6. doi: 10.1080/09553009314550041.
We have recently demonstrated by dielectric relaxation studies in the radiofrequency range that the sharp drop in the conductivity and permittivity of the membranes of chick embryo myoblasts in vitro, representative of fusion, is either delayed or completely blocked by sublethal doses of ionizing radiation (Santini et al. 1990a). The lowest of the doses investigated (3.25 Gy) caused a 10 h delay in myoblast membrane fusion when the cells were exposed at 24 h of culture, indicating that radiation-induced membrane injury had occurred. The purpose of this study was to determine if the myoblast system under investigation shows the same radiosensitive characteristics if irradiated with 3.25 Gy at various stages of differentiation. Consequently, the myoblasts were exposed to this dose at two different stages of differentiation (12 h or 48 h of culture). We show here that the time at which the myogenic cells are irradiated (state of differentiation) does not seem to affect the magnitude of the fusion delay (which was used as a measure of radiosensitivity of the myoblasts). In fact, the sharp drop in both membrane conductivity and membrane permittivity occurs with the same 10 h delay independent of the time of exposure. The role played by the plasma membrane in determining myoblast response to radiation damage is discussed.
我们最近通过对射频范围内的介电弛豫研究表明，体外培养的鸡胚成肌细胞发生融合时，其膜的电导率和电容率急剧下降，而亚致死剂量的电离辐射会延迟或完全阻断这种下降（桑蒂尼等人，1990a）。当细胞在培养24小时时受到照射，所研究的最低剂量（3.25戈瑞）会使成肌细胞膜融合延迟10小时，这表明已经发生了辐射诱导的膜损伤。本研究的目的是确定所研究的成肌细胞系统在不同分化阶段受到3.25戈瑞照射时是否表现出相同的放射敏感性特征。因此，在两个不同的分化阶段（培养12小时或48小时）对成肌细胞进行了该剂量的照射。我们在此表明，成肌细胞受到照射的时间（分化状态）似乎并不影响融合延迟的程度（将其用作成肌细胞放射敏感性的指标）。事实上，膜电导率和膜电容率的急剧下降均延迟10小时出现，与照射时间无关。本文讨论了质膜在决定成肌细胞对辐射损伤反应中所起的作用。
