Increased Endogenous Respiration of Ascites Tumor Cells after Radiation Exposure

Abstract

In the study of effects of radiation on ascites tumor cells, the properties of this biological system offer several noteworthy inherent advantages. These mammalian cells have a much more homogeneous cell population than animal tissues, which contain a variety of cell types. The ascites tumor cells divide rapidly and can be -xposed to a dose of X-irradiation, 1250 r, which will inhibit mitosis but will not produce lethal effects or alter cell concentration (1). The ascites tumor is a free cell suspension and offers an opportunity to study a level of organization not easily obtainable with animal tissues. Furthermore, the ascites cells are readily grown, harvested, counted, washed, and isolated. Several effects of radiation on Ehrlich ascites tumor cells have been reported by Klein and Forssberg (1, 2). Their observations on mitotic inhibition, cell volume, cell nitrogen content, and DNA synthesis have been confirmed. In the course of studies on biochemical effects of radiation on Ehrlich ascites tumor cells, we have observed that X-irradiation, 1250 r, causes a marked elevation in the endogenous oxygen consumption of these cells. In this work, presented in this communication, the cells were grown in the peritoneal cavity of mice and irradiated in vivo. Although radiation-induced alterations in the oxygen consumption of ascites tumor cells are not necessarily related to effects of radiation on the respiration of other tissues, it is of interest to note several reported effects of whole-body X-irradiation on the endogenous oxygen consumption of various mammalian tissues. These reports, however, are not in agreement. Kunkel and Phillips (3) reported an elevation in the endogenous respiration of rat liver homogenates after 200 r of wholebody X-irradiation. In support of this, an increased respiration of liver slices from rats exposed to 450 r was observed by Hanel et al. (4). Kuznets (5), on the other hand, reported a radiation-induced decrease in the endogenous oxygen consumption of rat liver homogenates. Barron (6) observed some depression, after 800 r, in the