Amount of 14C Assimilated in Different Organs and Tissues of the Rat After a Single Injection of [U-14C]glucose

Abstract

Labelling of proteins and lipids of 20 organs and tissues of the rat was studied 4 h after subcutaneous injection of D(+)-[U-14C]glucose. Gross differences between the rate of labelling of acid-insoluble constituents of various organs were noted; specific radioactivities of protein fractions obtained from the pancreas, plasma, ileojejunal segment of the alimentary tract, thymus, and spleen were equal to or higher than those of the brain protein fraction. This indicates that, apart from the brain, the high rates of assimilation of glucose carbon occur at anatomical sites of release of proteins, of rapid cell proliferation, or of immunological responses. In comparison with the above-mentioned organs, the rate of incorporation of glucose carbon into protein fractions of the heart, skeletal muscles, and formed elements of blood was low. In all organs and tissues investigated significantly more glucose carbon was incorporated into protein fractions than into lipid fractions, with the exception of adipose tissue, where glucose carbon was incorporated mainly into the lipid fraction.