THE RATE OF FORMATION OF STEARIC AND PALMITIC ACIDS IN NORMAL MICE

Abstract

The appearance of stably bound deuterium in fatty acids of animals given heavy water to drink can be taken as an indicator of fat formation (1, 2).All fatty acids hitherto investigated, with the exception of the doubly and triply unsaturated acids (3), take part in a continuous process of synthesis and destruction.By determining the rate of "uptake" of deuterium into the fatty acids of different organs of animals on a fat-free diet, it is possible to obtain an indication as to the relative "activity" of various organs in regard to fatty acid formation.The faster the process of fat formation in a particular organ, the faster the "uptake" of deuterium into its fatty acids.Site of Fatty Acid Formation-The heavy water content of the body fluids of mice was artificially raised to 2.4 to 4.4 per cent by methods previously described.The mice were kept on a diet low in fat for 2, 3, 6, and 15 days respectively, when they were killed.Fatty acids were isolated from the fat tissues, liver, intestinal wall, and kidneys.Except for the material from the latter organ, the acids were separated into the saturated and unsaturated fractions and their deuterium content determined (Table I).If formation of fatty acids had occurred mainly in one organ, the deuterium content of its acids should be higher than in those of any other organ.This, however, is true only in experiments of short duration.