Abstract
1. The specific radioactivity of [14C]glycerol released during the incubation of brown fat with [14C]glucose is much greater than that of the tissue lipid glycerol. 2. From a study of the release of [14C]glycerol from pre-labelled brown fat, it is concluded that the tissue contains a pool of glycerides with a higher rate of turnover than those in the main lipid store. 3. This pool contains newly synthesized glycerides, has a half-life of 25–30min and supplies about 25% of the glycerol liberated by brown fat. 4. Thus, a significant fraction of the total14C incorporated from glucose into brown-fat lipids is released as [14C]glycerol during an incubation.