HYPOTHERMIA AND KIDNFA^— ANDJUS 



21; 



The first type of experiment consisted of recording the urinary sodium con- 

 centration after an intravenous injection of 50 per cent glucose solution to rats 

 kept at different levels of hypothermia. Osmotic diuresis resulted, provided the 

 body temperature did not fall below 18-20° C. This was characteristically followed 

 by a marked sodium retention at body temperatures above 23° C. (fig. 4). At lower 

 temperatures, the osmotic diuresis was not followed by the disappearance of sodium 

 from urine, indicating possible failure of the sodium reabsorption mechanism 

 (fig. 5). Similar results were obtained by eliciting glucosuria and osmotic diuresis 

 with phloridzin. 



The second type of experiment consisted of studying sodium excretion in hypo- 

 thermic rats deprived of the antidiuretic hormone. It was first found that it is 

 impossible by injecting water to obtain a typical water diuresis accompanied by the 

 disappearance of sodium from urine in hypothermic animals below 30° C. of body 

 temperature. Moreover, when a typical diuresis following water injection is ob- 

 tained at normal body temperatures, it ceases promptly when such an animal is 

 subjected to cooling. The urinary concentration of sodium rises to that of plasma 

 levels by the time the body temperature falls below 25° C. Failure to induce sodium 

 retention by a water load in hypothermic animals and the interruption of this 

 retention by cooling could have been the consequence of a release of ADH elicited 

 by the cooling procedure, or of some other effect of low temperature on the hor- 

 monal mechanism regulating the function of renal tubules. In order to see, how- 

 ever, whether hypothermia has a direct effect on the reabsorption capacity of the 

 tubules, further experiments were performed on rats with permanent diabetes 

 insipidus provoked by hypothalamic lesions. These animals, deprived permanently 



RAT d 2659 



1/c Hall 



Fk;. 4. — Osmotic diuresis in a rat maintained at 26-29° C. of body temperature after an 

 intravenous injection of 2 ml. of 50 per cent glucose solution. Marking as before (Andjus 

 and Morel, 1952). 



