Efflux of free fatty acids from adipose tissue.

SCHIMMEL, RICHARD J., AND H. MAURICE GOODMAN. &Z'$~UX of free fatty acids from adipose tissue. Am. J. Physiol. 221(l) : 118-122. 197 1 .-Segments of rat epididymal adipose tissue were preincubated in Krebs-Ringer bicarbonate buffer for 30 min in the presence of epinephrine. The release of free fatty acids (FFA) formed during the preincubation period into albumin-containing media was measured during a subsequent 60-min reincubation in which quinacrine hydrochloride (3 mM) was added to block further lipolysis. Approximately 40% of the FFA formed during the preincubation period was released from the tissues into the medium during the reincubation; FFA not released were recovered from the tissues. In contrast, tissues which were boiled for 3 min prior to reincubation or reincubated in the presence of the metabolic poisons iodoacetate or 2,4-dinitrophenol released only 15 y. of their FFA. Release of preformed FFA was markedly reduced when the tissues were incubated under anaerobic conditions. Pyruvate stimulated release of FFA. Release of preformed FFA was unimpaired by omission of Na+, K+, or divalent cations from the reincubation medium. Ouabain was similarly without effect. These data are consistent with the view that release of FFA from adipose tissue in the presence of 3 mM quinacrine does not occur by passive diffusion but may be an energy requiring process.