238 Scientific Proceedings (129) 



115 (2075) 



Certain applications of the Donnan equilibrium to human 

 blood serum. 



By DANA W. ATCHLEY, ROBERT F. LOEB, and ETHEL M. BENEDICT 



(by invitation). 



[From the Department of Medicine of the College of Physicians 

 and Surgeons, Columbia University, and the Presbyterian 

 Hospital, New York.] 



Some months ago the authors found 1 in comparing some 

 physical and chemical properties of serum and serous effusions 

 that qualitatively certain definite relations obtained, regardless 

 of the nature of the cause of the edema. Some of the rela- 

 tionships observed were : that the potassium content of serum 

 is always higher than that of the effusion, the chlorine con- 

 tent of the serous fluid is higher than that of the serum, while 

 sodium and HCO s are apparently equally distributed. It was 

 found, furthermore, that when serum and serous fluid were 

 separated by a collodion membrane and the system was per- 

 mitted to come into equilibrium these relationships persisted. 

 In this work it was suggested that the relationships existing 

 between serum and serous effusion were the result of a mem- 

 brane equilibrium and that the quantitative differences were 

 apparently a function of the protein concentration. 



In recent experiments we dialyzed human serum against 0.8 

 per cent. NaCl brought to a P H of 7.4 by means of NaHC0 3 

 until the serum was practically potassium free. This dialyzed 

 serum protein in various dilutions (made with the NaCl solu- 

 tion) was then dialyzed against 0.8 NaCl at a P H of 7.4 and 

 at equilibrium, the concentrations of Na and CI were determined 

 in the serum within the collodion sac and the outside fluid. 

 It was found that [CI] was greater in the outside fluid than 

 in the serum and the difference was greater the higher the pro- 

 tein concentration in the sac. Apparently the [Na] was greater 

 within the sac containing serum than in the surrounding fluid 



1 Robert P. Locb, Dana W. Atchley and Walter W. Palmer, Jour. Gen. 

 Physiol, 1922, iv, 591. 



