PHYSIOLOGY OF RADIATION INJURY 989 



picture of intoxication follows heavy exposure even though the kidney is 

 shielded (McQuarrie and Whipple, 1922). An exception to the lack of 

 abnormalities in the kidney with moderate amounts of radiation is the 

 acute necrosis of the developing tubules and glomeruli of baby chicks 

 (W. Bloom, 1948; Steamer et al., 1951). The severe renal damage is 

 thought to predispose to early deaths in these animals (Steamer et al., 

 1951). 



There is some evidence of inhibition of kidney respiration and of oxida- 

 tion of substrates requiring sulfhydryl enzymes (Barron, 1946) ; this has 

 not been verified, however (DuBois, unpublished observations, 1950; 

 LeMay, 1951). Although extensive studies of glomerular and tubular 

 function have not been made, there is reason to believe that kidney 

 function is not impaired, except possibly in the agonal period following 

 acute irradiation of the whole body (Prosser, Painter, Lisco, et al., 1947). 

 In the dog, urinary excretion of water and nitrogen is not altered appreci- 

 ably, and the specific gravity of urine remains relatively constant. 

 Polyuria is seen in rats and rabbits during the first few postirradiation 

 days. Excretion of sodium, potassium, and chloride is increased in the 

 former on the first and fifth days (Edelmann, 1949). Increased urine 

 output is not always associated with polydipsia and may be a result, at 

 least in the rat, of an antidiuretic substance from the pituitary (Edelmann 

 and Eversole, 1950). Several days before death, water intake is generally 

 reduced in all species; urinary output is diminished less than water intake 

 (Prosser, Painter, Lisco, et at., 1947). Although an increased clearance of 

 phenol red has been observed in a few dogs during the second week 

 following median lethal dosages of X rays, a late diminished renal func- 

 tion is suggested by the marked terminal increase in blood nonprotein 

 nitrogen and in urea nitrogen. This is probably not a result of direct 

 radiation injury to the kidneys, but rather of the terminal circulatory 

 impairment and renal hemorrhage. 



ENDOCRINES 



Adrenal. It is recognized universally that the adrenal glands consti- 

 tute a buffer against a variety of traumatic conditions. The nonspecific- 

 ity of the adrenal response to stress and its role in the general adaptation 

 syndrome have been ably presented by Selye (1946) and elaborated upon 

 by others (Sayers, 1950). Ionizing radiations, in common with other 

 noxious stimuli, induce changes that are presumed to reflect an increased 

 demand for the adrenal hormones. In the absence of these secretions 

 susceptibility to irradiation is augmented. The functional response of 

 the adrenals does not appear to be a direct result of their irradiation. 

 Rather, it is mediated by the pituitary and closely resembles that seen 

 following a host of injuries. These considerations along with the appar- 



