RATE OF PEXBTRATION OF PHOSPHATIDES THROUGH THE CAPILLARY WALL 2(55 



Table 2. — Rati; of Escape of Labellkd 



Phosphatides thkottgh the Capillary 



Wall of a Rabbit Weighing 2.8 kgm 



Serontl (experiment 



Timp 



Per cent of labelled phos- 

 phatides injected into the 

 jnc;ular vein, present in 

 the total plasma 



Thico objections may be raised against the conclusions drawn above: a) Lal)!'!- 

 led phosphatides can be decomposed in the plasma leading, for example, to the 

 formation of labelled inorganic P; h) they can be incorporated into the corpuscles: 

 c) they can be synthesised in the body of rabbit B, into which labelled plasma 

 was injected. In that case, besides a loss of the labelled phos[)hatides introduced 

 into the circulation of rabbit B, some gain of such phosphatitles due to a synthesis 

 of labelled phosphatides in rabbit B would take place. 



The objections mentioned above are, however, not justified, as 



a) We recovered (see Table 6) more than 1/2 of the labelled phosphatides injected 

 into the plasma of rabbit B 4 hours later in the organs investigated, in spite of 

 the fact that the latter did not include the skin, the skeleton, and large parts 

 of the digestive tract, which presumably took up an appreciable part of the labelled 

 phosphatides. Furthermore, in the course of 4 hours, a non-negligible part of th(^ 

 phosphatides present in some of the organs and, thus, also that of the labelled 

 phosphatides taken up by these organs, was renewed. In the liver, about 

 1/6 of the phosphatides piesent was found to be renewed in the course of 4 hours'. 

 In view of the above considerations, the amount of phosphatides decomposed 

 in the plasma in the course of a few minutes can certainly be disregarded. 



h) That in the course of a few houis the replacement of corpuscle phosphatides 

 Vjy plasma phosphatides is a restricted one, is seen from the following figuies. 

 In two experiments, after the lapse of 4 hours, 2 resp. 1.3 per cent of the labelled 

 phosphatides originally present in the plasma of rabbits weie found to be located 

 in the corpuscles. 



As to objection c), the formation of labelled phosphatides does not take place 

 in rabVjit B to an\- significant extent in view of the absence of a sufficient amount 

 of labelled phosphate. This fact is seen from the following consideration: We admi- 

 nistered to rabbit A 5x10^ counts as phosphate and found the next day in the 

 plasma of this rabbit 40,000 counts. We inje(!ted into rabbit B 20 cc. plasma 

 containing 8000 counts, of which 4000 were due to phosphatide P and 4000 

 to inorganic P. As from ox 10^ inorganic P counts introduced 20,000 phosphatide 

 counts were found after the lapse of a day in rabbit A, we (^an conclude that, 

 within that time, less than 20 phosphatide^ counts wci(> foinicfi in rabbit B, thus 

 an insignificant amount. 



iQ. llEVE.SY and L. IIahn, Del Kgl. Dan-she Vidensk. Sel-skab, Biol. Mcdd. 

 15, 5 (in40). 



