3-methylcholanthrene Concentration and Clearance in Some Adipose Tissues in Mice.

The 3-methylcholanthrene (3-MC) concentration following intraperitoneal ad ministration was determined spectrophotofluorometrically in benzene extracts of the mammary fat pads and interscapular fat pads of female mice. The following consistent relationship in 3-MC concentration existed when varying dosages of the carcinogen were given in sesame oil: fourth mammary fat pad < third mammary fat pad < interscapular brown fat pad. As the 3-MC dosages increased lineally, the tissue con centration of 3-MC increased nonlineally when examined 7 hours after injection. The peak concentration occurred 10 hours after the intraperitoneal injection of 30 mg. of 3-MC. Clearance of 3-MC from mammary fat pads, which had been isologously transplanted from donor mice 9 hours after injection of 30 mg. of 3-MC, was ex tremely slow. The tissue concentration 10 days after transplantation was still slightly higher than that of the controls. The carcinogen had a greater affinity for the mammary parenchyma than for mammary fat.