Brown adipose cells: spontaneous mobilization of endogenously synthesized lipid.

Isolated brown adipose cell devoid of a basement membrane, readily synthesized a variety of lipids from radioctive acetate, a reactionaugmented by glucose and insulin. A large proportion of the newly formed fatty acids passed into the incubation medium. In intact brown adipose slices and isolated white adipose cells, most of the synthesized lipid was retained as glyceride esters. The date suggest that the rapid turnover of endogenously synthesized lipid in brown adipose cells is almost totally obscured in studies with intact tissue slices because of interstitial barriers to the egress of fatty acid.