PITUITARY AND ADRENALS— HUME, EGDAHL and NELSON 173 



to exogenous ACTH is likewise markedly reduced, apparently as a direct effect of 

 lowered temperature on the adrenal cortical cells. 



2. Adrenal medullary secretion of e])inephrine and n()repinci)hrine is sharply 

 reduced in hypothermia. 



3. By contrast, cold exposure without the development of hypothermia does not 

 alter adrenal responsiveness to ACTH. 



4. The induction of hypothermia per se under anesthesia, hut in the ahsence of 

 trauma, did not act at any time as a stimulant to pituitary-adrenocortical secretion. 



REFERENCES 



1. Aronow, L. : To be published. 



2. Egdahl, R. H., NeLson, D. H., and Hume, D. M. : The effect of hypothermia on 17-hydroxy- 



corticosteroid secretion in adrenal venous blood in the dog, Science 121: 506, 1955. 



3. Egdahl, R. H., Nelson, D. H., and Hume, D. M. : Adrenal cortical function in hypothermia, 



Surg., Gynec. & Obst., 101: 15, 1955. 



4. Egdahl, R. H., and Richards, J. B. : The effect of extreme cold exposure an adrenocortical 



function in the unanesthetized dog, Am. J. Physiol., in press. 



5. Ganong, W. F., Bernhard, W. F., and McMurrey, J. D. : The effect of hypothermia on the 



output of 17-hydroxycorticoids from the adrenal vein in the dog. Surgery 38: 506, 1955. 



6. Hume, D. AL, and Nelson, D. H. : Adrenal cortical function in surgical shock. Surgical 



Forum, American College of Surgeons, 5: 568, 1954, W. B. Saunders & Co., Philadelphia, 

 1955. 



7. Hume, D. M. : To be published. 



8. Khalil, H. H. : Effect of hypothermia on the hvpothalamic-pituitary response to stress, Brit. 



M. J. 2: 72>2,, 1954. 



9. Nelson, D. H., and Samuels, L. T. : A method for the determination of 17-hydroxycorti- 



costeroids in blood : 17-hydroxycorticosterone in the peripheral circulation, J. Clin. Endo- 

 crinol. & Metab. 12: 519, 1952. 



10. Nelson, D. H., and Hume. D. M.: Corticosteroid secretion in the adrenal venous blood of 



the hypophysectomized dog as an assay for ACTH, Endocrinology 57: 184, 1955. 



11. Nelson, D. H., Egdahl, R. H., and Hume, D. M. : Corticosteroid secretion in the adrenal 



vein of the non-stressed dog exposed to cold. Endocrinology 58: 309, 1956. 



DISCUSSION 



Dr. A. D. Keller: We have made observations of dogs having graded hypo- 

 physectomies. These correlate well with Dr. Hume's observations. The hypophysec- 

 tomized dog, regardless of the magnitude of the hypophysial deficiencies, tolerates 

 cold without an adrenal insufficiency crisis being precipitated. The dog that is 

 almost totally hypophysectomized. so that there is practically no adrenal cortex left, 

 has such a reduced resistance to cold that on exposure a progressive hypothermia 

 develops. 



Dr. M. E. DeBakey: I wonder if Dr. Hume would tell us what was the body 

 temperature of the dogs who were exposed to —78° C. 



Dr. Hume: They remained normal. 



There are two other points which are perhaps worth noting. (;)ne is that when 

 you measure peripheral corticoid levels, you are measuring not only adrenal corti- 

 coid production but also peripheral destruction and excretion. Both of these factors 

 are reduced under hypothermia. Although corticoids are being produced in smaller 

 amounts than under normal circumstances, they are also 1)eing destroyed more 

 slowly, because the aliility of the liver to conjugate, and thus inactivate, them is 



