Insulin by Extraction 



417 



203 (2163) 



Relative amounts of insulin obtained by extraction and by 

 perfusion of the pancreas. 



By H. D. CLOUGH and J. R. MURLIN. 



[From the Physiological Laboratory of the University of Roch- 

 ester, Rochester, N. Y.] 



We have employed two essentially different methods for ob- 

 taining insulin from the excised pancreas of various animals : 

 First, extraction with different media after maceration of the 

 pancreases; and secondly, perfusion of the intact organs with 

 various solutions. In a series of twenty-nine perfusions done 

 during the past ten months we have purposely varied the many 

 factors involved — such as the composition of the perfusion fluid, 

 the temperature of the chamber containing the organs, the rate 

 of perfusion, volume of perfusate, time of perfusion, and per- 

 fusion pressures — within wide limits* in order to select the sim- 

 plest method which is efficient. A comparative analysis of these 

 various factors leads us to conclude that the simplest efficient 

 method is that of continuous gravity perfusion with 0.2 per cent. 

 HC1 at or somewhat above body temperature (37C. to 45C), 

 under a pressure of 120 mm. Hg, for a period of one hour. 



In determining the potency of preparations we have used a 

 dose of two cubic centimeters of final concentrated product ad- 

 ministered subcutaneously to normal rabbits. Blood is taken 

 from the ear veins before the injection and again two hours after 

 the injection. A drop of 70 milligrams in blood sugar is taken 

 as a rabbit unit and on this basis the yield in rabbit units per kilo 

 of pancreas is calculated. 



The perfusion method appears to give about three times as 

 much insulin (estimated as Rabbit Units) per kilo as is obtained 

 by the extraction methods employed and gives a product which 

 is much more easily and quickly concentrated because of the 

 absence of the large amounts of protein and extraneous material 

 which were obtained when extraction processes were used. 



