PHYSIOLOGY OF RADIATION INJURY 971 



flow in man is likewise unchanged by moderate amounts of local irradia- 

 tion and may actually decrease with larger dosages (Ane and Burch, 

 1941). However, an increased spread of intradermally injected Evans 

 blue dye, presumably indicative of an enhanced lymph flow, has been 

 seen in the rabbit within a few hours after irradiation (Painter et al., 1947). 

 Lymph output has not been measured in the later periods after exposure, 

 although there is some indication of an increased flow from the thoracic 

 duct in irradiated dogs (Bigelow et al., 1951). Reference has already 

 been made to extravasation of red cells into the lymph (Furth, Andrews, 

 et al., 1951). 



Edema, especially of the face, neck, and extremities, may be observed 

 during the acute terminal period. While edema of the viscera, particu- 

 larly of the gastrointestinal tract, may also be noted in some animals, 

 edema is more often microscopic rather than macroscopic. Consistent 

 changes in water content have not been observed in muscle, adrenal, 

 kidney, and gastrointestinal tract (France, 1946; Beutel and Winter, 

 1935; Patt et al, 1947; Painter, 1948; Bowers and Scott, 1951b). In 

 chronically irradiated rats, muscle and bone water increase slightly after 

 the accumulation of nearly 1500 r over a period of 105 days (Brues et al., 

 1946). Total-body water in mice is increased by about 8 per cent on the 

 fifth day after acute X irradiation (France, 1946), but there is little 

 change in the total water content of dogs following a nearly completely 

 lethal dosage of X rays (Soberman et al., 1951). 



Extracellular fluid in rats, estimated from the thiocyanate space, has 

 been shown to increase by about 2 cc per 100 grams of body weight during 

 the first two weeks after whole-body X irradiation with 400 or 700 r. An 

 increase over the range of the control animals has also been noted eight 

 months after a single exposure to 750 r, and similar changes occur after 

 chronic irradiation with X rays or a rays from plutonium (France, 1946). 

 Although an early increase in the extracellular compartment has been 

 reported in a few irradiated dogs (Prosser, Painter, Lisco, et al, 1947), 

 consistent changes are not evident from other experiments in the same 

 dosage range (Soberman et al., 1951). 



Sodium retention has been described in the rat during the first few days 

 following irradiation (Painter, 1948; Bennett et al., 1949), but similar 

 increases in sodium space do not occur in the dog after lethal irradiation 

 (Soberman et al., 1951). The lack of agreement may be related to differ- 

 ences in water intake between the two species, since the rat generally 

 manifests a marked polydipsia during the first post irradiation day while 

 water intake is reduced in the dog (Prosser, Painter, Lisco, et al., 1947). 

 On the other hand, there is reason to think that inanition, and not 

 polydipsia, is responsible for the increased sodium space in the rat since 

 similar changes have been seen in the gastrointestinal tracts of starved 

 and both starved and irradiated rats (Painter, 19-18). Whenever body 



