Relation of fatty acid structure to release and esterification of free fatty acids

After incubation of rat adipose tissue with corticotrophin in buffer-albumin, the composition of the free fatty acids (FFA) in the tissue and in the medium was determined; the medium contained proportionately more myristic, palmitoleic, linoleic, and linolenic acids. The ratio of the amount of each free acid in the medium to that in the tissue increased with decreasing chain length and increasing unsaturation. Free acids produced in adipose tissue by corticotrophin stimulation were esterified by subsequent exposure of the tissue to glucose and insulin. Among the saturated and monoenoic acids the shorter chain components were esterified to a greater extent, while at a given chain length the more unsaturated acids were more readily esterified. Thus the more polar FFA were more readily released from and esterified in adipose tissue. These results could have been produced by a variety of processes including differences between the acids in aqueous solubility or the presence of tissue-binding sites with varying affinities for the different acids.