Time Course Changes of Tissue Protein Synthetic Ability of Rat after Meal and Influence of Dietary Protein Deficiency on It's Ability

Abstract

Male rats weighing from 110g to 140g which had received daily spaced-feeding for two hours with a normal diet (20% casein) or a protein-free diet for 7 days were killed at the 3 rd, 10 th and 22 nd hr after the last meal, and the incorporation of ¹⁴C-glycine into tissue protein by liver slices and isolated soleus muscles was measured. The results obtained are summarized below.
The incorporation by liver slices from rats on the normal diet was increased markedly at the 10 th hr, but no such increment was observed in rats on the protein-free diet. It is seemed that the protein synthetic ability of liver is increased when dietary amino acids from the alimentary tract are supplied to liver at a larger extent. At the 22 nd hr, the incorporation was decreased remarkably in the both lots.
Feeding on the protein-free diet reduced the incorporation to about the half of that on the normal diet only at the 10 th hr, whereas little difference in the incorporation was observed between feeding on the two diets at the 3 rd and the 22 nd hr.
With the soleus muscle, the incorporation both on the normal diet and on the protein-free diet was decreased in time course after the last meal and it at the 22 nd hr was lowered by about 30% and about 20% less than that pertaining to the two diets at the 3 rd hr.
The incorporation in rats fed the protein-free diet fell to about the half of that on the normal diet irrespective of time course after the last meal.