Folate Metabolism in the X-Irradiated Rat

Abstract

Tissues from x-irradiated rats have been analysed for changes in folate activity. Blood and liver total folate levels were unaffected. Total folate levels were lowered in the spleen, and the decrease in the conjugated folate levels of the bone marrow from irradiated rats was quite significant. An observed rise in "free" bone marrow conjugase levels in the irradiated animals could be correlated with accumulation of unconjugated tetrahydrofolates in the tissue at the expense of the metabolically more active conjugated derivatives involved in nucleic acid biosynthesis. There was a decrease in the folate-dependent incorporation of the β-carbon atom of serine into bone marrow nucleic acid fractions from irradiated rats. The hydrolytic bone marrow folyl conjugase activity had an acidic pH optimum and in comparative studies was shown to exhibit a structure-linked latency similar to acid phosphatase, a known lysosomal marker enzyme.