Inhibition of ribonucleotide reductase in thymocytes of rats treated by ditiocarb sodium.

The i.p. administration of ditiocarb sodium (diethyldithiocarbamate, DDC) at doses of 500 and 1000 mg/kg body wt. decreased within 1 h and in a competitive manner the ribonucleotide reductase (RNR) activity of rat thymocytes by about 25 and 40%, respectively. Under the same conditions, scheduled DNA synthesis was inhibited by almost 30 and 75%, whereas RNA synthesis remained unchanged. 1000 mg DDC/kg body wt. resulted in a long-lasting diminution in thymus weight; the spleen revealed no significant drug effects. It is suggested that the decrease of RNR activity in thymocytes of DDC-treated rats is a major determinant in the (reversible) inhibition of DNA synthesis which, in turn, may be implicated in the radio- and chemoprotective effects of the drug.