FORMATIOX OF PHOSPHATIDES IX LIVER I'EKFLSION EXFEIU.MEXTS 



259 



phosphatides formed amounting to only about 0.1% of tlie total amount 

 present. No differenee was found in the behaviour of normal and lipaemic 

 bloods. 



FORMATION OF LABELLED PHOSPHATIDES IN PERFUSION 



EXPERIMENTS 



Through the great kindness of Prof. Lundsgaard and Dr Blixen- 

 CRONE, who carried out perfusion experiments on isolated livers, we were 

 enabled to test the formation of labelled phosphatides in the blood of 

 cats circulating through an isolated liver and also in the liver tissue. 

 To 120—160 ml. of cat blood diluted to about twice its volume with 

 physiological NaCl solution a minute amount of active sodium phos- 

 phate was added. The blood was then defibrinated and allowed to circu- 

 late through an isolated liver for 2.5 hr. The labelled inorganic P present in 

 the blood was determined at the start and at the end of the experiment 

 and also the labelled phosphatide P of blood and liver at the end of 

 the experiment. The ratio of the specific activity (activity per mgm P) 

 of the blood phosphatide P to that of the blood inorganic P is seen from 

 Table 1. In interpreting the figures of the table we should recall that 

 if all phosphatides molecules present are newly formed the specific 

 activities of the inorganic P and phosphatide P should be equal. The 



Table 1 

 Specific activity of blood phosphatide P 



Specific activity of blood inorganic P 



(average value) 



Normal blood (av. of 3 exps.) 

 Lipaemic blood (av. of 2 exps.) 



0..5 X 10^3 

 1.6 X 10^3 



1.2 X 10^3 

 3.4 X 10~3 



0.85 X 10~3 

 2.5 X 10-3 



figure of 0.85 xlO"^ for the ratio quoted, for example, shows that the 

 new formation of phosphatide molecules within the experiment amounts 

 to only 0.085%. In the course of the experiment inactive inorganic P 

 of the liver and also a part of the P present in the organic P compounds 

 of the liver exchange with the active plasma inorganic P and lower the 

 specific activity of the latter. The specific activities of the plasma inor- 

 ganic P being thus different at the start and at the end of the experiment 

 we have calculated the ratio (seen in Table 1) for the beginning of the 

 experiment (col. 1), for the end (col. 2), and also an average value (col. 3). 

 The figures of Table 1 for normal blood hardly differ from the figures 

 obtained in the experiments in vitro (average value 0.8x10"^). While, 



17* 



