Protein and amino acid metabolism in posterior hemicorpus of acutely uremic rats.

Protein synthesis and degradation and net uptake and release of amino acids and minerals were examined in the perfused hemicorpus of bilaterally nephrectomized and sham-operated control rats. Animals were studied 30 h after surgery. In comparison with controls, uremic rats had greater urea N appearance (net urea generation) and lower plasma and muscle concentrations of most amino acids. Muscle protein synthesis was not altered, but protein degradation was greater in uremic versus sham rats. There was greater net release of phenylalanine, tyrosine, alanine, total nonessential amino acids, total amino acids, potassium, and phosphorus from the perfused hemicorpus of uremic rats and greater release of citrulline from sham rats. ATP, creatine phosphate, cAMP, and activities of cathepsin B1, cathepsin D, and alkaline protease were not different in muscles of the uremic versus sham rats. Thus, in acutely uremic rats there is increased protein wasting in the hemicorpus due to enhanced protein degradation. The enhanced protein degradation does not appear to be due to increased muscle cathepsin B1, cathepsin D, or alkaline protease activities.