Studies on the Metabolism of Tissue Proteins

Rats were injected with proline-U-14C and exposed to total-body x-irradiation at various time-intervals thereafter. Proline was isolated from the soluble protein and elastin fractions of various organs and its specific activity determined. In most organs an increase in specific activity of proline of these two protein fractions was observed after irradiation. This was interpreted to mean either a lowered metabolic replacement or a loss of certain components from these protein fractions after irradiation. It is suggested that the decrease in specific activity observed in the spleen is correlated to changes in the cell-population in this organ after irradiation.