Originally published in Nature 132, 952 (1938) 



47. FATE OF THE SULPHATE RADICAL IN THE 



ANIMAL BODY 



A. H. M. Atens jun. and G. Hevesy 



From the Institute of Theoretical Physics Univei-sity 



of Copenhagen 



Phosphorus enters as phosphate in the numerous compounds in which 

 it is to be found in the animal l)ody ; in connexion with the investi- 

 gations carried out in recent years concerning the fate of ingested phos- 

 phorus atoms in the organism, it seemed to be of interest to determine 

 whether or not, in the course of the numerous metabohc processes in 

 which phosphorus is involved, the phosphate radical exchanges its 

 oxygen content with other oxygen atoms present in the body. This 

 question could be answered by injecting into an animal sodium phosphate 

 which contained heavy oxygen (^^O) as an indicator and then deter- 

 mining if the phosphate recovered in the urine, for example, contained 

 more than the normal amount of ^^O. 



As, however, it was recently found^ that "heavy-oxygen phosphate" 

 can be obtained by dissolving sodium phosphate in "heavy-oxygen 

 water" and vice versa, it is apparent that the oxygen atoms present 

 in phosphate radicals exchange their places freely in water and there 

 can be scarcely any doubt that the probability is extremely small of 

 a phosphate radical leaving the body coupled to the same oxygen atoms 

 with which it entered. Sulphate ions, on the other hand, have been 

 found^ to exchange oxygen atoms either not at all or at a very slow 

 rate with neutral water, even at 100° C, and it seemed of interest, 

 therefore, to investigate whether sulphate ions during their circulation 

 in the body participate in chemical reactions which loosen the oxygen 

 bonds sufficiently to make an oxygen exchange possible. 



In the experiments we wish to report here, sodium sulphate containing 

 heavy oxygen was prepared from heavy-oxygen water, kindly presented 

 to us by Prof. Urey^ having a density 740 parts in a million greater 

 than that of normal water. The reaction used for the preparation of the 

 "heavy sulphate" was that which takes place between SO2CI2 and heavy- 

 oxygen water in the presence of traces of iodine as a catalyst. 1 gm. of 

 the dry material, converted into 50 cc. of solution, was injected into a 

 rabbit. The urine of the rabbit was then collected for 24 hours, its 

 sulphate content recovered as barium sulphate, the oxygen content 



30 Hevesy 



