Excretion of Metabolites of 7, 12-Dimethylbenz (^|^alpha;) anthracene Injected Intravenously into Rats

Abstract

DMBA (7,anthracene) is a potent carcinogen and under specific conditions is capable of inducing 100% incidence of mammary cancer in rats') 2) . Since few informations are available on the binding of DMBA to DNA and protein in the parenchymal cells of rat mammary gland, such experiments might be considered to be highly desirable for correlation of carcinogenecity with the binding of specific carcinogens to macromolecules in susceptible tissues3) . But it is still a problem whether or not organ susceptibility to the carcinogen directly depends on the accumulation (uptake and clearance) of chemical carcinogen in the target organ. In order to clarify these problems radiometric and autoradiographic studies on the distribution of labeled carcinogens in main tissues should be done. Some radiometric investigations on main organs of the rats administered with labeled DMBA have been reported4) 5) . In this communication, macroradioautographic observations on female rats, injected Or. by labeled DMBA, and radiometric analysis on the excretion of its metabolites are presented. Materials and methods Experiment IBy means of our procedure), 250 pCi of 9, 10-Dimethy1-1,2-benzanthracene-9-C", The Radiochemical Centre, Amersham, was dissolved in 0.5 ml of Dimethylsulfoxide and incorporated into 4.5 ml of DMBA emulsion made by Upjohn Company, Kalamazoo. One ml of this hot DMBA emulsion contains 4.5 mg of DMBA and exhibits 50 /JCL Five Sprague-Dawley female rats, aged 45 days and weighed approximately 120 g, were injected by 0.5-1.0ml of the labeled DMBA emulsion from a caudal vein, and sacrificed by ether 5, 10, and 30 minutes, and 2, and 16 hours after the single administration, respectively. The animals were frozen in acetone-dry ice mixture, and cut on a freezing microtome. The frozen sections were dried through a week. Macroradioautographic observations were performed on the freeze-drying sections'. Experiment IIAs previously reported5), 5 mCi of 9, 10-Dimethy1-1, 2-benzanthracene-T(G), The