Utsumi H, Elkind M M
Radiat Res. 1983 Nov;96(2):348-58.
A clone of V79 Chinese hamster cells (V79-AL162/S-10) with unique properties has been isolated after a challenge of parental cells (V79-AL162) with 1 mM ouabain. Compared with parental cells, or with other clones isolated after the ouabain challenge, these cells form smaller colonies, are more sensitive to both X rays and fission-spectrum neutrons, and respond atypically to a postirradiation treatment with caffeine. Their enhanced response to X rays results mainly from a large reduction in the shoulder of their survival curve, probably because in late S phase, the most resistant phase in the cell cycle, the survival curve of these cells has a reduced shoulder width. Caffeine, and to a lesser extent theophylline, added to the colony-forming medium immediately after exposure appreciably increases the width of the shoulder of these sensitive cells, whereas caffeine has the opposite effect on the response of normal V79 cells. Because dibutyryl-cAMP added immediately after exposure actually further sensitizes these sensitive cells, it would appear that the enhanced survival due to methylxanthines, which inhibit cAMP phosphodiesterase, does not result from increases in intracellular levels of cAMP. Thus the unique response of the V79-AL162/S-10 cells to a radiation posttreatment with caffeine (increased survival) results from a net increase in their ability to repair damage that is otherwise lethal; caffeine treatment ordinarily prevents normal V79 cells from repairing damage that is only potentially lethal.
在用1 mM哇巴因处理亲代细胞（V79-AL162）后，分离出了具有独特特性的V79中国仓鼠细胞克隆（V79-AL162/S-10）。与亲代细胞或哇巴因处理后分离出的其他克隆相比，这些细胞形成的集落较小，对X射线和裂变谱中子均更敏感，并且对咖啡因的照射后处理反应异常。它们对X射线的增强反应主要源于其存活曲线肩部的大幅减小，这可能是因为在细胞周期中最抗辐射的S期后期，这些细胞的存活曲线肩部宽度减小。在照射后立即添加到集落形成培养基中的咖啡因，以及程度较轻的茶碱，会明显增加这些敏感细胞存活曲线肩部的宽度，而咖啡因对正常V79细胞的反应则有相反的作用。由于在照射后立即添加的二丁酰-cAMP实际上会使这些敏感细胞进一步敏感化，因此看来抑制cAMP磷酸二酯酶的甲基黄嘌呤所导致的存活增强并非源于细胞内cAMP水平的升高。因此，V79-AL162/S-10细胞对咖啡因照射后处理的独特反应（存活增加）是由于其修复原本致命损伤的能力净增加；咖啡因处理通常会阻止正常V79细胞修复仅具有潜在致死性的损伤。
