THE METABOLISM OF I131BY SURVIVING SLICES OF RAT MAMMARY TISSUE1

Abstract

Surviving slices of rat mammary tissues were used to study extrathyroidal I metabolism in the Warburg apparatus. Lactating and non-lactating slices incorporated inorganic I131 into moieties which were insoluble in trichloracetic acid. Organic binding could be inhibited by 1-methyl-2-mercaptoimidazole or by boiling the tissues prior to incubation. In media containing sufficient 1 -methyl-2-mercaptoimidazole to inhibit organic iodinations, lactating mammary slices established slice/medium differentials for inorganic I131 which exceeded 1.0. Concentration gradients could be depressed by monovalent anions such as thiocyanate or perchlorate, or by metabolic inhibitors such as 2,4 dinitrophenol.