Enzymes in Irradiated Tissues 43 



amide (DuBois, Cotter and Petersen, 1955) or p-aminobenzoic 

 acid (Thomson and Mikuta, 1954) or to form hippuric acid 

 (Schrier, Altman and Hempelmann, 1954) was unimpaired. 

 It therefore appears that both coenzyme A and the enzymes 

 concerned with these acetylations function normally. The 

 level of coenzyme A and of nicotinic acid, which is some 

 measure of DPN and TPN, remained normal in the early 

 stages of X-ray cataract (van Heyningen, Pirie and Boag, 

 1954). The level of pyridoxin in the liver remains unaltered 

 (MacFarland et ah, 1950). Glutathione has not been found 

 to decrease in any tissue immediately after radiation (Bacq 

 and Alexander, 1955). 



The glycolytic activity of tissues has not been extensively 

 studied. One particular investigation will be described later 

 but here one can say that where individual enzymes concerned 

 in glycolysis have been examined no change has been found 

 immediately after radiation. Thus aldolase, glyceraldehyde 

 phosphate dehydrogenase and lactic acid dehydrogenase of 

 lens, liver, kidney and spleen are not early affected (van 

 Heyningen, Pirie and Boag, 1954; DuBois and Petersen 1954). 



Throughout, one has been expecting a fall in enzyme 

 activity; but results show that some enzyme processes are 

 immediately increased. Altman, Richmond and Solomon 

 (1951) showed that if the bone marrow was removed from 

 rabbits immediately after giving 800 r to the whole animal 

 and the synthesis of saturated and unsaturated fatty acids 

 from labelled acetate was measured in vitro the irradiated bone 

 marrow had 2-3 times the activity of the normal (Table II). 

 The oxygen uptake by the tissue was also greater. The actual 



Table II 



Effect of Radiation on the Synthesis of Fatty Acids and on 

 Respiration of the Bone Marrow of the Rabbit 



.o/ ^«%«^!^« , O^ uptake 



( % pre-radiation value) ^i Q^jg. wet wt. 



Saturated Unsaturated in 3 hours 

 No radiation 100 100 300 



hours 231 344 810 



48 hours 108 — 280 



