PHYSIOLOGY OF RADIATION INJURY 909 



Lartigue, 1950b). On the other hand, when beets are added to the basic 

 ration, the number of hemorrhages is increased and the LD 50 is decreased 

 from 350 to 150 r. This may be attributed possibly to a relative defi- 

 ciency of vitamin C. Ascorbic acid does not alter the hemorrhagic state 

 or the survival of irradiated dogs although it may act synergistically with 

 flavonoids (Field and Rekers, 1949b). Flavonoids have been shown to 

 improve the survival of X-rayed guinea pigs and rats, but this has not 

 been verified by others, and the value of these substances requires further 

 elucidation (Kohn, Robinett, and Cupp, 1948; Clark et al., 1948; Sokoloff 

 et al, 1950; Cronkite et al, 1949). 



It is of interest that rutin does not protect the dog against dosages 

 greater than the LD 50 (Field and Rekers, 1949a). This suggests perhaps 

 that the hemorrhagic tendency in the dog is a minor factor in mortality 

 resulting from higher dosages of radiation. While hemorrhage may be 

 extensive at the LDioo, its control with toluidine blue or protamine does 

 not permit survival (Allen et al., 1948). Life may, however, be pro- 

 longed for a week or two, suggesting perhaps that the control of hemor- 

 rhage in less severely irradiated animals may contribute to recovery. It 

 is well known that many animals, including the dog, succumb with only 

 minor evidence of hemorrhage, again emphasizing the importance of 

 multiple factors. 



BODY FLUIDS 



Some disturbance in water and electrolyte metabolism may be antici- 

 pated following exposure of large areas of the body to ionizing radiation as 

 a result of the vomiting, diarrhea, altered food and water intake, tissue 

 breakdown, and bleeding, which are prominent features of the radiation 

 syndrome. The degree of redistribution of body fluids will depend, in 

 large measure, on the capacity of the homeostatic mechanisms, which may 

 also be affected by radiation, to maintain the delicate balance of the 

 internal environment. It is clear, therefore, that the body fluids reflect a 

 number of influences that may vary not only with dosage and from animal 

 to animal but also from time to time after irradiation in the same animal. 

 While it appears that early death after massive irradiation is accom- 

 panied by hemoconcentration and dehydration, disturbances of water 

 and electrolyte balance after median lethal dosages are, in general, com- 

 paratively mild and probably do not constitute an important cause of 

 death. 



Blood and Plasma Volume. The blood volume remains relatively con- 

 stant or is only slightly diminished after irradiation of the whole body 

 with dosages that approximate the median lethal. This obtains in the 

 face of a greatly reduced erythrocyte volume because of the compensatory 

 increase in the volume of plasma (Prosser, Painter, Lisco, et. al., 1947; 

 Storey et al., 1950; Soberman et al., 1951). The decrease in red blood 



