Adipose tissue (AT) function is regulated by both short-term and long-term mechanisms. Long-term adaptations to hormonal, nutritional, and developmental factors take place over a time course of hours to days. For example, chronic alterations in the hormonal milieu (analogous to those that may occur during over- or underfeeding) have long-term effects on the cellular capacity for lipogenesis and lipolysis (1 –3 ), as well as on the production of adipocyte secretory proteins (4 ,5 ). The mechanisms underlying these metabolic adaptations may involve pre- or posttranscriptional events that change the amount of enzyme protein or the number or activity of specific receptors or transporters. Elucidation of the mechanisms of long-term adaptations requires methods that maintain the function for AT ex vivo for periods up to 1 wk.
