Indirect effect of x-radiation on the respiratory metabolism of Ehrlich ascites tumour cells and mitochondria.

M H Silk,A O Hawtrey,I J C Macintosh,F Gilowey,A D A Cooke

doi:10.1038/bjc.1959.85

Abstract

Various proteinaceous and nonprotsiuaceous physiological media were incubated 3 hours at 37 deg C with mouse antero-latsral abdondnal wall tissue without radiation and with 1000 roentgen x radiation of the medium plus tissue prior to incubation. The respiratory and glycolytic metabolism of Ehrlich ascites cells and mitochondria was then compared in corresponding batches of media prepared with and without radiation. In some experiments oxidizable substrates were added to the media, while in others substrates liberated from the mouse abdominal wall tissue served to maintain respiration of the added ascites cells or mitochondria. With bicarborate buffering, intact ascites cells showed lower aerobic glycolysis and markedly elevated oxygen uptake in the x-irradiated medium. With phosphate buffering the opposite effect was observed. Both intact ascitte cells and mitochondria showed lower oxygen uptake in the x-irradiated msdium. Mitochondria showed lower P/O ratios in the x-irradiated msdium than in the corresponding non-irradiated control. Since neither the cells nor the mitochondria were directly radiated, the results demonstrate an indirect effect of x radiation on respiratory metabolism. The effect operates via the environmental medium irradiated in contact with a tissue selected to represent the normal tumor-bed and stroma of the Ehrlich tumor. The indirect effect does notmore » seem due to radiolysis of the environmental medium itself, nor do organic hydroperoxides appear to be responsible. It is suggested that metabolic products from the irradiated tissue are liberated into the medium, and that these influence the respiration rate of added Ehrlich ascites cells and mitochondria.« less

Highlights

(1) Aerobic glycolysis of Ehrlich ascites cells in ascites plasma incubated with mouse antero-lateral abdominal wall The aerobic glycolysis of Ehrlich ascites cells was compared in 6 corresponding b)atches of ascites plasma incubated with abdominal wall tissue from healthy mice (a) non-irradiated and (b) 1000 roentgen X-irradiated before incubation
(11) P/O ratio of Ehrlich Ascites cell mitochondria in phosphate buffered medium incubated with mouse antero-lateral abdominal wall As part of the experiments to measure 02 uptake of Ehrlich ascites cell mitochondria, the P/O ratios of these particulates were determined in 7 corresponding batches of phosphate buffered medium incubated with healthy mouse tissue (a) without radiation and (b) with 1000 roentgen X-irradiation before incubation
The repiratory and glycolytic metabolism of Ehrlich ascites cells and mitochondria was compared in corresponding batches of media prepared with and without radiation

Summary

MATERIALS AND METHODS

Mouse antero-lateral abdominal wall Mice were killed by cervical fracture. A median incision was made in the ventral aspect of the abdomen. For use as a medium in which to determine both the glycolysis and respiration of intact Ehrlich ascites cells, the plasma was fortified with 0.25 per cent w/v glucose before incubation with mouse tissue. This amount of succinate was adequate to serve as substrate for the mouse antero-lateral abdominal wall tissue during incubation, and for respiration of the Ehrlich cells allowed to metabolise in the medium after incubation. Final concentrations in each flask were as follows: potassium phosphate buffer (pH 7.4), 0.045 M; KF, 0.015 M; MgC12, 0-008 M; ADP, 0.0025 M; AMP, 0.001 M; EDTA, 0.002 M; glucose, 0-034 M; KC1, 0.01 M; sucrose 0-062 M; DPN, 2.4 x 10-4 M; cytochrome-c, 9.8 x 10-6 M; hexokinase, 1-2 mg. All other substrates and chemicals were of Analytical Reagent grade, and where necessary were neutralised to pH 7.4 with potassium hydroxide before use

RESULTS

Findings

DISCUSSION

SUMMARY