On the turnover of tissue lipids in the mouse during dietary deprivation

1. 1. The double isotope ratios of individual lipid fractions in major tissues of mice were determined before and after a period of total dietary deprivation. 2. 2. Several significant alterations in these ratios were caused by this treatment, with a marked individuality evident in the response of separate tissues. 3. 3. The increased metabolic flux overall was contributed to by increased rates of lipid degradation in liver, and active mobilization from the peripheral depots. 4. 4. Significant utilization of phospholipid fractions for energy purposes was also noticeable, however. along with tissue specific variation in the patterns of both double isotope ratios and specific radioactivities. 5. 5. These data are discussed in relation to the comparative priorities of synthesis and degradation in the different tissue and lipid sources in response to this physiological perturbation.