Insulin and the in vitro protein synthesis of liver and skeletal muscle ribosomes in experimental acute uraemia.

Tissue dependent alteration of liver and muscle protein synthesis was previously observed in acute uraemia, when intracellular amino acids were used as substrate. Since protein synthesis depends also on substrate availability, it was of interest to investigate the role of isolated liver and skeletal muscle ribosomes of nephrectomized rats and their susceptibility to in vivo insulin stimulation. Under marked uraemic conditions, no difference was demonstrated between controls and uraemic animals; after insulin administration and in the presence of endogenous messenger both liver and muscle ribosomes showed an enhancement of [3H]-phenylalanine incorporation of 20% and 54% respectively in controls, and of 32% and 45% respectively in uraemic rats. This study may rule out the influence of acute uraemia on protein synthesis capacity of isolated ribosomes and emphasize the importance of intracellular amino acid availability in altered protein synthesis.