Nucleic acid metabolism in the spleen and liver of rats subjected to chronic fractionated γ-irradiation

Fractionated γ-irradiation of rats (50 R/day, 2 months) caused an early decrease in the weight of the spleen and quantity of cells. RNA concentration in lg spleen varied insignificantly. DNA amount in 1 g and the content of both nucleic acids, calculated per organ, was decreased, as compared to normal, within almost entire period of observation. The intake of [14C]orotic acid into DNA decreased at small doses and increased after a cumulative dose of 1000 R exceeding the control level by 6-13 times. Changes in the liver were much less pronounced. A quantitative estimation of a contribution of the spleen to myeloid hemopoiesis has prompted a conclusion that this organ plays an unimportant part in the hemopoiesis compensation (with the irradiation model under study)