TURNOVER OF LECITHIN, CEPHALIN AND SPHINGOMYELIN 



323 



T.\BLE 8. — Specific Activity of the Cellular Inorganic P .\nd Phosphatide 



P Extracted from the Organs 



RabVjit VII. — Weight: 2.4 kgm. 

 Siibciitaneoiis injection during \l.r> honi-s 



<') Turnover rate calculated on the assumption that the formation of phosphatides took place with 

 incorporatiou of cellular inorganic P. 



<") Turnover rate calculated on the assumption that the formation of phosphatides took place with 

 incorporation of extracellular inorganic P. 



*'> As the presence of traces only of 'cone Pin the marrow sample investigated lowers the specific activity 

 of the marrow inorganic P, the recorded figure for the inorganic P of the marrow may be too low and that 

 recorded for the rate of renewal of the phosphatide P of the marrow, correspondingly, too high. 



Table 9. 



Extent of Renewal of Phosphatides 



Rabbit IX. — Weight: 2.5 kgm. 

 Subcutaneous injection during 50 days 



<') Rate of renewal calculated on the assumption that the formation of phosphatides took place with 

 incorporation of cellular inorganic P. 



(*) Rate of renewal calculated on the assumption that the formation of phosphatides took place with 

 incorporation of extracellular inorganic P, 



the specific activity of the average plasma phosphatide P. As shown 

 on page 340, the specific activity of the phosphorus present in different 

 phosphatide fractions can differ substantially, but, in spite of exhaustive 

 fractionation processes no fraction of extremely high or extremely low 

 specific activity was found. Furthermore, the total amount of labelled 

 phosphatides formed in the intestinal mucosa in the course of 4 hours 

 amounts to only 1/5 of that formed in the liver during the same time. 

 In this connection it is of interest to remark that, according to the 

 results obtained by Sullmann and Wilbrandt which are discussed 

 on page 309, the intestinal lympli carries up to 0.1 mgm phosphatide 



21* 



