Changes in serum putrescine and spermidine levels following local radiation to hepatoma 3924A of the rat.

Local irradiation of tumors of rats bearing 3924A hepatomas resulted in more than a doubling of the putrescine levvel and nearly a doubling of spermidine concentration in the serum within 12 hr. Within 24 hr, the putrescine concentration had increased four-fold in the serum, along with a continued increase in the spermidine concentration. The decrease in the spermidine concentration of the tumor paralleled increased levels of spermidine in the serum, whereas the concentrations of polyamines in the liver were unchanged. These changes are similar to previously reported changes in the spermidine concentration in sera and in tumors following the administration of a single dose of 5-fluorouracil to rats with 3924A hepatomas. Since local irradiation was confined to the tumor, we conclude that the increases in putrescine and spermidine detected in the serum are derived from the tumor tissue with no involvement of the host tissues.