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The effects of X-radiation on lactate metabolism of mammalian cells

1965; Elsevier BV; Volume: 37; Issue: 3 Linguagem: Inglês

10.1016/0014-4827(65)90212-0

1090-2422

J. F. Whitfield, H. Brohée, T. Youdale,

DNA Repair Mechanisms

There were two distinct phases of lactate production in suspension cultures of irradiated (1500 r) rat thymocytes. Lactate was produced during the first hour after irradiation. Production then stopped only to resume after 3 hr. Unirradiated cells did not produce lactate after an initial production during the isolation procedure. The first phase of lactate production in irradiated cultures was probably a combined result of the isolation trauma and exaggeration of this trauma by radiation. The second phase followed the disappearance of the characteristic reticulo-granular chromatin structures of the nucleus and the disappearance of stainable DNA-associated histone. These cytological symptoms accompany cell death. In a medium without phosphate, the postirradiation development of cytological damage was inhibited and the cells consumed the lactate produced during isolation instead of making more. In the presence of phosphate, there was a strong stimulation of lactate production and development of cytological damage by irradiation. Exposure of cells to spermidine (0.10 M) or a high Na+ concentration (260 mEq/l) immediately after irradiation strongly retarded the development of cytological damage, but they did not retard lactate production. These agents strongly stimulated lactate production in unirradiated thymocyte cultures. Exposure of thymocytes to 0.10 M nicotinamide from 0 to 3 hr after irradiation prevented further development of cytological damage and further production of lactate. Irradiation (1500 and 1700 r) of suspension cultures of the more radio-resistant L mouse cells which rapidly consume lactate during the later phases of growth resulted in a transient inability to consume lactate. The cells fully regained their ability to consume lactate 8 to 16 hours after irradiation. Possible mechanisms underlying these initial metabolic effects of irradiation are outlined and discussed.