972 RADIATION BIOLOGY 



tissue is catabolized, for example, in starvation, water is made available, 

 and this may be a factor in the animal which is anorexic as a result of 

 irradiation. Changes in the irradiated animal, however, are not entirely 

 comparable to those observed in starvation; there is apparently little 

 change in extra- and intracellular muscle water in the irradiated rat, 

 whereas, in the starved rat, the extracellular phase is expanded and the 

 intracellular contracted. 



Water transfer is closely related to the exchange of its principal ionic 

 solutes and both solvent and solute must be considered in any evaluation 

 of hydration phenomena. Although there is evidence that heavy irradia- 

 tion may lead to cell swelling (Buchsbaum and Zirkle, 1949; Failla, 

 1940), simultaneous measurements of sodium, potassium, and chloride 

 indicate that intracellular fluid may actually be decreased at the expense 

 of the extracellular phase in the gastrointestinal tract of rats after mid- 

 lethal exposure of the whole body (Painter and Pullman, 1950). It is of 

 interest that there is a rather parallel loss of sodium and potassium from 

 radiosensitive tissues in the rat during the first day or two after X irradia- 

 tion (Bowers and Scott, 1951a, b). This is followed by a marked increase 

 in tissue sodium. There is also no evidence for an increase in intracellular 

 water in irradiated dogs (Soberman et al., 1951). 



These considerations indicate that there is probably little serious dis- 

 turbance in water balance after acute lethal irradiation. Changes appear 

 to be more severe in rats than in dogs, which may be a result of the greater 

 diarrhea in the former. Water intake is reduced more than water loss in 

 most mammals. Since plasma volume may be increased in the presence 

 of an increase in extracellular and total-body water, the extra water may 

 be derived from metabolism or from a reduction of the respiratory loss, 

 which may be as high as 35 per cent of the extrarenal loss under basal 

 conditions. 



Constituents of Plasma and Lymph. Plasma proteins are decreased in 

 concentration in guinea pigs and rats, but usually not in dogs, during the 

 first week after total-body X irradiation. The maximum decrease, 

 amounting to about 1 gram per cent, occurs around the fifth postirradia- 

 tion day in guinea pigs and rats (Kohn, 1950, 1951a; Hanschuldt and 

 Supplee, 1949). The plasma refractive index parallels early protein 

 change. After the initial decrease, protein concentration levels off or 

 may return toward the normal value. In the dog, plasma protein con- 

 centration remains unchanged or may decline slightly during the first 

 and second postexposure weeks (Prosser, Painter, Lisco, et al., 1947a; 

 Soberman et al., 1951). This may be followed by a rise above the control 

 level in nonsurvivors during the terminal period. Total protein of 

 lymph collected from the thoracic duct fluctuates during the first two 

 days after irradiation and then decreases slowly for several days (Brown 

 et al., 1950). Maintenance or increase of the plasma protein concentra- 



