Oxidative Phosphorylation in Irradiated Cells 83 



cells are inspected, the detection of cytological change is much 

 more sensitive than the estimation of oxidative phosphory- 

 lation which has to be carried out on the pooled mitochondria 

 from all the cells in a tissue. When, on the other hand, the total 

 number of damaged nuclei is compared with the overall 

 change of phosphorylation it may be stated that the develop- 

 ment of nuclear and mitochondrial damage runs roughly 

 parallel. In recent experiments results were obtained which 



•/• 



100--O-0 



50 



V4V2 



T 

 2 



r 

 4 



IT 

 5 3 



T 

 4 



T 

 5 



T 

 5 



n 



Fig. 1. Oxidative phosphorylation of rat spleen mito- 

 chondria at various periods after total body irradiation 

 (700 r). Substrate: succinate. Abscissae: hours after 

 irradiation. Ordinates: percentage of corresponding 

 control values. Wliite circles: oxygen uptake. Black 

 circles: phosphate uptake, n: number of experiments. 



suggest that a biochemical defect in spleen mitochondria is 

 present as early as 30 minutes after total body irradiation, 

 when the only demonstrable cytological effect is the inhibition 

 of mitosis. These experiments will be described in one of the 

 following sections. 



Tissue specificity of the effect 



A rough survey has been made of the occurrence of the 

 disturbance of oxidative phosphorylation after total body 



