Rate of Protein Synthesis in Man 



195 



The rate of clearance of urea from the urea pool in equation 

 1 is determined by the size of 'EJV. The half time, t^yg) 

 is given by 



^ti/2=In 2=0-693 



(5) 



Since Eu/U is approximately 2, ti/2 is close to 1/3 day or 

 eight hours. In this period half of the urea present in the 

 urea pool will be excreted. 



o 



S 



z 

 < 



UJ 



a: 



o 

 o 

 o 



-J 



Ol 



lu 



X 



u. 0.1 



O 



z 

 i= 0.067 



ABS 



JI 



_, * 



50 100 



TIME MINUTES 



150 



Fig. 2. Isotope concentration of the urea pool following intra- 

 venous injection of ^^N urea. 



The same results can be obtained in determining the rate 

 of excretion in the urine of the labelled urea. If A^ is the total 

 urea ^^N excreted in the urine, then a plot of the logarithm 



jl — ^1 vs. time yields a straight line (see Fig. 3). The 



slope of this line is equal to E^/U. 



of 1 



