218 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



RAT c? 225g 



A/cUalL 



lllllllllllllllllllllllllll 



2rnl Glucose 90% i.v. 



Fig. 5. — Osmotic diuresis in a rat maintained at 21-22° C. of body temperature after the same 

 hypertonic load as in the experiment illustrated liy figure 4. 



of ADH, and showing a continuous maximal sodium retention at normal body 

 temperature, failed to retain sodium when cooled to below 23° C. The urinary 

 concentration of Na-^ rose to plasma levels (fig. 6). 



These results, which are in accordance with the data obtained by Bickford and 

 Winton ( 1937 ) on the isolated kidney, speak in favor of a direct inhibitory effect 

 of hypothermia on the reabsorption activity of the renal tubules. In a range of 

 tempei"atures between 18 and 23° C, sodium reabsorption is completely inhibited, 

 while glomerular filtration and urinary flow are still present. Such a reversilile dis- 

 sociation of the kidney functioii suggests the use of the hypothermic animal as a 

 special experimental preparation for the renal physiologist. 



REFERENCES 



1. Andjus, R. K., and Morel, F. : L'excretion hydrominerale au cours de I'hypothermie 



etudiee chez le rat a I'aide du radio-sodium Na'^, C. R. Soc. Biol. 146: 1477, 1952. 



2. Bickford, R. G., and Winton, F. R. : The influence of temperature on the isolated kidney of 



the dog, J. Physiol. 89: 198, 1937. 



DISCUSSION 



Capt. Philip A. Riley, MC: At the Walter Reed Army Institute of Research 

 we have studied urine production and composition during hypothermia to 20° C. 

 in dogs, and noted several interesting changes. 



The minute vohime of urine excreted increased progressively as the animals 

 were cooled, despite a marked reduction in filtration rate. This increase in m"ine 

 flow was unaltered by antidiuretic hormone. 



The urine composition was also affected by the decrease in temperatinx-. 11ie 

 urine became j^rogressivelv more alkaline as cooling progressed mitil it approached 



