552 ADVENTURES IN RADIOISOTOPE RESEARCH 



Comments on paper 55 



The balance of phosphorus intake and excretion has been investigated in nume- 

 rous cases. A vast literatiiie on this subject is available in which the route of 

 secretion is often considered, i. e. the ratio of urinary to faecal phosphorus of the 

 human subject or the animal investigated. To what percentage the phosphorus 

 excreted in the faeces is due to unabsorbed material and to phosphorus originat- 

 ing from the body proper were, however, not known before the application of 

 radioactive indicators. This application of ^-P is reported in paper 55. The suppo- 

 sition that the specific activity of urinary phosphorus parallels that of digestive 

 secretion, an assumption on which the method applied is based, was tested later 

 by KjERULF — Jensen (1941). He was able to support the above supposition. 

 Among others, he compared the specific activity of the total phosphorus in samples 

 of bile-pancreatic juice with the specific activity of urinary phosphorus, and 

 found that 1 week after administration of labelled phosphorus the specific activ- 

 ity of the total phosphorus in bile -pancreatic juice samples was already very near 

 the value of urinary phosphorus. When interpreting the figures obtained for 

 endogenous and exogenous phosphorus content in faeces, we must envisage the 

 possibility that some phosphate interchange takes place thiough the intestine 

 wall and that, correspondingly, the endogenous phosphorus present in the faeces 

 may be partly secreted and partly interchanged phosphorus. The method outlined 

 in paper 55, can be used to determine what percentage of almost any element 

 present in the faeces is of endogenous origin. 



Reference 



K. Kjerulf- Jensen (1941) Acta Physiol. Scand. 3, 1. 



