120 



Scientific Proceedings (126) 



58 (2018) 



Protein content of frog's plasma. 



By R. A. BIETER and F. H. SCOTT. 



[From the Department of Physiology, University of Minnesota, 

 Minneapolis, Minnesota.] 



In the Journal of Experimental Pathology of October, 1921, 

 Hill and McQueen made some observations on capillary pressure 

 of the frog's kidney, which they believe indicate that filtration is 

 not possible. They found capillary pressure of about 10 milli- 

 meters, while the pressure in the arterioles was from 25 to 30 

 millimeters. A pressure of 10 millimeters might still be large 

 enough to produce filtration if the colloid content of the frog's 

 blood was low enough. We have accordingly made some deter- 

 minations on the protein content of the frog's plasma. This was 

 done by drawing blood from the heart of frogs into tubes con- 

 taining finely divided potassium oxalates. The blood was then 

 centrifuged and the plasma obtained. Kjeldahl determinations 

 were done on the plasma and reckoning the total nitrogen found 

 as all protein, and using the factor 6.25, the protein of the frog's 

 blood is between 0.6 and 0.8 per cent. — approximately 10 per 

 cent, of that of mammals. With this small colloidal content it 

 is evident that very few millimeters of mercury would be suf- 

 ficient to permit filtration. Thus the low capillary pressures 

 observed by Hill and McQueen are no arguments against filtra- 

 tion. 



It may be noted that Halliburton 1 gives the content of frog's 

 plasma at about 2.5 per cent, protein. Our results were obtained 

 from frogs in the late fall, and whether Halliburton's results 

 are due to a seasonal variation or whether it is a difference of 

 method we do not know, as Halliburton does not give details as 

 to how he obtained his plasma. 



l Journal of Physiology, 1886, vii, 319. 



