[Different mechanisms of blood thymidine levels caused by irradiation and polyanion administration]

The administration of dextran sulfate causes an increase in the thymidine content of rat blood comparable with the postirradiation thymidinemia. In contrast to radiation dextran sulfate does not increase polydeoxynucleotide content of thymus. Isoptin, a calcium antagonist, decreases thymidinemia induced by dextran sulfate to a greater extent than that induced by ionizing radiation. Thymidinemia induced by dextran sulfate is supposed to be due to its effect on cell membranes. In radiation-induced thymidineamia this mechanism is of lesser significance.