Rate of Protein Synthesis in Man 



193 



The total urea in the organism, U mg. N, is the urea pool. 

 Urea enters it at the rate of E^ mg. N per day and leaves it 

 at the same rate via the urine. Since we assume the animal 

 is in the stationary state, the rate of protein breakdown, R, 

 is equal to S. 



Protein Pool 



F 



Grams N- 



R 



Metabolic Pool 

 P 

 Grams N- 



Y 



Urea Pool 

 U 



Grains M- 



■>Ku 



For the Stationary State : S=R, D=Et. 

 where : — 



D. Rate at which Dietary Nitrogen enters the Metabolic Pool 



as Grams/day. 

 R. Rate at which Nitrogen from Protein breakdown enters the 



Metabolic Pool as Grams/day. 

 S. Grams of Nitrogen/day used for Protein Synthesis. 

 Et. Rate of Total Urinary Nitrogen Excretion as Grams/day, 



and Et = Eu+Ex. 



Fig. 1. 



If we define the total excretion of N in the urine to be 



Et, then:- 



Et = Eu -|- Ex 

 R-S 

 D=Et 



It is clear that if we are to be able to understand the 

 factors which determine the rate of excretion of a sample of 



ISOTOPES 



14 



