KINETICS OF PRIMARY REACTIONS AND CHEMICAL PROTECTION 321 



level (5 to 10 per cent) is sufficient to increase a slow reaction. Appar- 

 ently the same applies to irradiated biolipids. 



We have established for instance (Tarusov, 1957; Polivoda, 1960; 

 Zhnravlev, 1960) that lipid extracts from the livers of irradiated mice 

 are less able to decrease chemolnminescence, observed in oleic acid 

 during its oxidation in the atmosphere, than extracts from control 



25n 



3 5 7 



Days after irradiation 



Fig. 6. 



* 2 



10 



animals. With the use of highly sensitive methods for the detection of 

 weak radiation we could establish that homogenates of the liver of 

 mice were producing slight radiation of the type observed in the oxida- 

 tion of fats, (about 4,000 to 5,000 r). In irradiated animals it is more 

 intensive. Cysteine and other protective substances stop this lumin- 

 escence. 



The second important feature is that with an increase of the density 

 of ionization the main kinetic indicators of the radiochemical oxidizing 

 reaction are weakened and even disappear ; the oxygen effect is lacking, 

 and anti-oxidizing substances do not give protection. In the literature 

 there are very few data on the absolute value of chemical protection, 

 i.e. the elimination dose. Therefore we undertook corresponding quanti- 

 tative investigations on yeast and mice and evaluated the data in the 

 literature. Each agent was tested in a series of experiments under 

 optimal conditions for the manifestation of i3rotective action (y-radia- 

 tion). It has been established that under optimal conditions chemical 

 protection neutralized less than 50 ])er cent of the dose. Maximum 

 protection came from the oxygen effect, both at an increase and a de- 

 crease of oxygen pressure (for yeast). That has been earlier noted by 

 some authors. 



The data show that besides primary oxidizing reactions there exist 



