NOTE OX THE IXORGANIC PHOSPHATE OF BLOOD PLASMA 



461 



In some cases, the amount of the total acid-solublo P present and its activity 

 were determined as well. In these experiments, the acid-solublo extract was ashed 

 and an ahquot used to colorimetric determination of the total (inorganic -f organic) 

 acid-soluble P present, another aliquot to radioactive measurements. 



RESULTS 



Numerous experiments were carried out leading to the result that 

 a difference is present between the behaviour of the inorganic phosphate 

 added and the endogenous inorganic phosphate, but the difference is 



10 

 Time in hours 



Fig. 1. Rate of disappearance of the endogenous inorganic P content 

 of human plasma and of the radiophosphorus added. 



not pronounced. As seen in Fig. 1 and other similar figures obtained by 

 us, the radioactivity of the plasma sample declines at a somewhat more 

 rapid rate than its inorganic P content. After the lapse of 18 hours 10% 

 of the inorganic P is still present, but only 4% of the activity added. 

 Thus, about 6% of the endogenous plasma inorganic P do not dialyse and, 

 consequently, do not get into exchange equilibrium with the labelled 

 phosphate of the plasma. In some experiments, up to 10% of the endo- 



