46 



Antoinette Pirie 



Table III 



Inhibition of Steroid Synthesis in Perfused Adrenal Gland by 



Gamma- RADIATION 



Dose 2,000-3,000 r 



Substrate 



Substance S 



DOC 



Progesterone 



21-Desoxy- 

 cortisone 



A^-Androstene- 

 3p-OH-17-one 



Transformation 

 product 



Hydrocortisone 



Corticosterone 



Hydrocortisone 



Cortisone 



lip-OH- 

 A*-androstene- 

 3 : 17-dione 



Decreased 



conversion 



per cent 



75, 34, 54 

 35, 55 



37 (+7) 



22, 19 



48, 21 



Specific 



reaction 



inhibited 



1 1 P -hydroxy lation 



1 1 [i-hydroxylation 



11(3, 17a + 



21 -hydroxylation 



2 1 -hydroxylation 



A5-3P-OH- 

 A*-3-ketone 



the ACTH-stimulation studies. Radiation therefore appears 

 to inhibit many of the steroid-synthesizing enzymes and to 

 have httle specificity. The inhibition is apparent immediately 

 radiation ceases though it is true that the time of radiation is 

 considerable as is also the dose. However, other systems in 

 vitro are far more resistant to radiation than this. A point of 

 interest is that the enzyme which catalyses lip-hydroxyl- 

 ations is active in mitochondrial preparations (Brownie and 

 Grant, 1956) and the effect of radiation can be tested therefore 

 on this isolated enzyme that seems to be radiosensitive in the 

 tissue. 



A further point is to try to relate the changes in the gland 

 in vitro with changes in vivo after radiation. Radiation of the 

 rat with 800 r causes loss of ascorbic acid and of cholesterol 

 from the adrenal within 1 hour (Bacq and Alexander, 1955). 

 Hochman, Bloch and Frankenthal (1953) found that 25-50 r 

 caused decrease in adrenal ascorbic acid tested 1 hour after 

 irradiation. The decrease, however, was not found to be dose 

 dependent; large doses still caused only about 26 per cent 

 decrease of adrenal ascorbic acid. Prof. Pincus tells me that 

 the ascorbic acid content of the adrenal glands used in his 

 perfusion work was extremely low and therefore no studies of 

 change during irradiation were made as it was felt these would 



