Preventive action of ATP on biosynthesis of uridylic nucleotides of uracil in rat tissues after prolonged γ-irradiation

Action of a single intramuscular injection of ATP (350 mg/kg) prior to the whole-body prolonged γ-irradiation of rats with a minimum lethal dose (1100 R; dose of 0.8 R/min) on the uracil phosphoribosyltransferase (UPRTF) and uridine-5'-phosphate-kinase (UMP-kinase) activity of extracts from thymus, spleen and liver has been investigated. It has been found that exogenous ATP has no protective action on postirradiation changes in the UTRTF activity of haemopoietic tissues, and have a small favourable action on the activity of this enzyme in the liver and the activity of UMP-kinase in the thymus and spleen. A single injection of ATP (the same dose) to non-irradiated animals causes a transient inhibition of UPRTF, but it has no effect on the UMP-kinase activity. Causes of inefficacy of exogenous ATP administered to rats prior to prolonged irradiation are discussed