Influence of valine flooding on channeling of valine into tissue pools and on protein synthesis.

Rates of valine incorporation into protein were measured under control and valine-"flooding" conditions and included correction for the degree of recycling of unlabeled valine derived from the steady-state breakdown of tissue protein into the precursor pool (tRNA bound). The correction factor lambda, which is the ratio of the steady-state specific activity of valine in the tissue tRNA-bound pool to that in the arterial plasma, was determined for each of the tissues. In controls, values of lambda ranged from 0.31 in adrenals to 0.54 in heart; in flooded animals, values were higher, but only in liver was the value of lambda close to 1.0. In control and flooded rats, rates of protein synthesis were highest in liver and adrenals and lowest in skeletal muscle, with intermediate values in brain and heart. Flooding resulted in increased rates of protein synthesis in liver and decreased rates in adrenals. Rates of protein synthesis in brain, heart, and skeletal muscle were not statistically significantly affected by flooding.