372 



ADVENTURES IN RADIOISOTOPE RESEARCH 



considerations mentioned above are discussed in detail in the publication 

 cited above on the turnover rate of phosphatides. In this paper is de- 

 scribed the method which permits us to calculate from the specific activity 

 of the tissue inorganic P. the specific activity of the plasma inorganic P, 

 the extracellular space of the organ, and the inorganic P content of the 



Tablio 2. — Extent of Renkwal of Diffeeent Fkactions of the Organic Acid 



Soluble P 



Rabbits II, III, and IV (average) 

 Intravenous injection during 4 houre 



Table 3. — Specific Activity of Acid Soluble P Fractions 

 Extracted from the Organs of the Rabbit 



Rabbit VII. Weight 2.4 kgm 

 Subcutaneous injection during 11.5 hours 



Fraction 



Plasma inorganic P 



Corpuscle inorganic P 



Corpuscle P hydrolysed 15 hours in 1 N 112804 at 100' 

 Corpuscle P hydrolysed 15—120 houi-s in 1 N HgSO^ at 10° 



Corpuscle non-hydrolysed residue 



Muscle inorganic P 



Muscle creatine P 



Marrow inorganic P(0 



Marrow organic P 



Brain inorganic P 



Brain organic P 



Specific activity 



at the end of the 



experiment 



100 

 25 



25 



2.5 



13.0 



15.5 



8.5 



13.1 



36.8 



3.0 



2.3 



<') The low value is presumably due to the presence of traces of slightly active bone P in the marrow sample- 



