Lysine turnover in man measured by intravenous infusion of L-[U-14C] lysine

Lysine turnover was measured in three adult subjects by intravenous infusion of L-[U-14C]lysine for periods of 27-30 hours. A plateau specific activity of free lysine was reached in the plasma after c. 12 hours. The total turnover rates, calculated in terms of g protein.kg body weight-1 day-1 were 1.56 in an adult aged 50, 3.24 and 3.07 in two young men 19 years old. The results are discussed in relation to previous measurements of total amino acid turnover in man made by different methods. They fall within the range found by the methods which are theoretically the most satisfactory. (AU)