Studies on folate metabolism in folic acid-deficient rats.

The distribution in liver of pteroylpolyglutamates and urinary excretion of folate metabolites was studied in folic acid deficient rats after injection of the vitamin, in order to evaluate the effect of folic acid deficiency on the conversion of the vitamin into actual coenzymic forms. Any significant difference neither in total activity nor in pteroylpolyglutamates of liver does not appear between deficient supplemented and unsupplemented animals. Also the urinary amounts of reduced metabolites in deficient rats do not increase after injection of folic acid. Therefore the inability of deficient rat liver to synthesize polyglutamates may be ascribed to the lower availability of tetrahydrofolates as they are the preferred substrates of pteroylpolyglutamate synthetase.