Rate of Protein Synthesis in Man 



197 



excretion of urea is not the rate determining step. If we set 

 up the equations governing the system shown in Fig. 1 it is 

 a relatively simple matter to show that 



-Bt 



Ap = AqC 

 in which 



Ap=mg. ^^N in the metabolic pool at any time t 

 Ao=mg. ^^N administered as amino-acid 



ET"i"S 



(7) 



B=- 



Table I 



Measurement of the Urea Space and its Relation to Body Weight in 



Normal Male Subjects 



Equation 7 represents the amount of isotope remaining in the 

 metabolic pool at any time t. The larger the value of B the 

 more rapidly will the isotope content of the metabolic pool 

 decline. Part of the ^^N leaving the metabolic pool will do 

 so by conversion to urea and transfer to the urea pool. 

 The amount of ^^N in the urea pool, A^, will be 



Au= 



AoEuU 



P(Eu-BU) 



/e-Bt_e-u* j 



(8) 



and the amount of ^^N excreted as urea in the urine, Ag, will 

 be 



A.= 



AqEu 



u 



P(Eu-BU) LB^^ ^ ^ E ^ ^ ^ 



(9) 



