Originally communicated in Kgl. Danske Videnskabernes Selskab. Biologiske 



Meddelelser, 15, (1940) 



30. RATE OF PENETRATION OF PHOSPHATIDES 

 THROUGH THE CAPILLARY WALL 



G. Hevesy and L. Hahn 

 From the Institute of Theoretical Physics, University of Copenhagen 



Ions or molecules of crystalline substances present in the plasma can 

 easily penetrate through the capillary wall. As soon as a few minutes 

 after injecting labelled sodium ions (^^Na^) into the jugularis, we find 

 these ions proportionally distributed between the sodium ('^3]s^a~^) ions 

 of the plasma and those of the interspaces. On the other hand, colloidal 

 particles like those formed by the proteins of the plasma under physiolo- 

 gical conditions pass through the walls of the capillaries at very slow 

 rate only. The phosphatides present in the plasma can be expected to 

 have an intermediary position as to their penetrability through the 

 capillary wall between the crystalline constituents and the proteins 

 present in the plasma. To determine the rate of penetration of the plasma 

 phosphatides through the capillary wall, we introduced labelled phos- 

 phatides (phosphatides containing radioactive P) into the plasma and 

 measured the rate of their disappearance from the circulation. 



The labelled phosphatides were obtained in the following way. Label- 

 led sodium phosphate was administered to a rabbit (A). The phosphati- 

 des formed, after the start of the experiment, in the liver and other 

 grgans of this rabbit become labelled ; a part of these labelled phospha- 

 tides is liberated into the plasma. By injecting plasma of this ral:)bit 

 (A) into the circulation of another rabbit (B), we introduced labelled 

 plasma phosphatides under strictly physiological conditions into the 

 circulation. To avoid the increase of the plasma volume of rabbit B, 

 we removed, previous to the injection of the labelled plasma, for example, 

 20 cc. blood of rabbit B. This blood was, after addition of heparin, 

 gently centrifuged to separate the bulk of its plasma content which 

 was then replaced by the labelled plasma of rabbit A. The blood thus 

 obtained was injected into the jugularis of rabbit B. This rabbit, thus, 

 gets its own corpuscles reincorporated, combined with the corresponding 

 amount of labelled plasma of the other rabbit. An aliquot part of the 

 plasma of rabbit A is kept to be analysed. 



The labelled phosphatide molecules introduced into the circulation 

 of rabbit B become distributed in the total plasma of the rabbit almost 



