Role of reducing agents, adrenal glands, and pituitary glands on the conversion of folic acid to citrovorum factor.

Abstract

The recovery of citrovorum factor present in the urine of male rats receiving folic acid is enhanced both by in vitro addition of ascorbic acid to the collection bottles and by in vivo stomach tube feeding of ascorbic acid. In vitro addition of glutathione or homocysteine produces the same increase in the recovery of citrovorum factor in the urine as that obtained with ascorbic acid while added cysteine is less effective. Adrenalectomy lowers the urinary excretion of preformed citrovorum factor by male rats receiving folic acid but does not affect the bulk of the citrovorum factor activity present in urine in the form of a heat-labile compound (N10 formyltetrahydrofolic acid). Hypophysectomy lowers the urinary excretion both of preformed citrovorum factor and of the heat-labile precursor. Administration of beef-growth hormone to the hypophysectomized rats almost doubles the excretion of citrovorum factor in male rats receiving folic acid. However, administration of adrenocorticotropic or thyrotropic hormo...