Comparative studies were made of immediate (within the first minutes) changes in intracellular ATP concentration after irradiation by different regimens. ATP concentration in cells at a stationary phase of growth increased immediately after irradiation with a dose of 5 Gy, reaching its maximum within 30-40 min. Irradiation with the same total dose, by the regimen of 0.1 + 4.9 Gy at a 3-minute interval between the doses, did not cause alterations in the ATP content in cells. It is concluded that the absence of the increase in the parameter under study (ATP) after irradiation by the latter regimen indicates that preirradiation at a dose of 0.1 Gy inhibits the adequate development of an early response to irradiation with a dose of 4.9 Gy.

Adenosine Triphosphate↗

PubMedDate not supplied

[The effect of He-Ne laser radiation on the survival of HeLa cells subjected to ionizing radiation].

A monolayer of HeLa cells, at the stationary phase of growth, exposed to He-Ne laser radiation (632.8 nm; 100 J/m2) either 5 min or 60 min prior to gamma irradiation (0.1-10 Gy; 6.75 Gy/min), or 5 min after irradiation has been investigated. With a 5-min interval between irradiation sessions (both sequences) the survival curves are virtually the same as those for gamma-irradiated cells only. With He-Ne laser radiation delivered 60 min before gamma irradiation with doses exceeding 5 Gy, a fraction of radioresistant cells is identified whose D0 is almost twice as high as D0 of basic cell mass (3.6 and 1.7 Gy respectively. The survival curve becomes a two-component one. A hypothesis is proposed that He-Ne laser radiation activates, in some cells, the processes that promote the repair of radiation damages.

Cell Survival↗

PubMedDate not supplied

[Problem of enhancing the biological action of ionizing radiations. 10. The radiosensitizing action of 5-nitrotryptamine].

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Animals↗