Amino Acid Interrelationships: The Effect of a Load of Leucine on the Metabolism of Isoleucine 1

Summary

The effect of a load of leucine on the metabolism of isoleucine was studied. Rats were fed L-isoleucine-(U)-¹⁴C and were given a load of leucine in gel form 12 hr later when the rate of ¹⁴CO₂ expired had become constant. This resulted in a significant increase in ¹⁴CO₂ expired, in every instance. This stimulation of the metabolism of isoleucine by a load of leucine offers an explanation for the previously observed depression of plasma isoleucine level after a load of leucine in human infants.