Hormone responsiveness of the lipoma: a tumor of adipose tissue.

The ability of adipocytes from lipomas to respond to lipolytic stimuli was investigated to determine whether diminished responsiveness could account for the excessive accumulation of neutral lipid which characterizes these tumors. Baseline studies were performed on rat adipose tissues to determine optimal conditions for comparison of lipolytic responses to a variety of hormones. Cell concentrations, the specific depot site from which the cells are derived, the age of the animal and the tissue preparation, as to whether fragments are used as opposed to collagenase-treated isolated cells, were determined to affect the lipolytic response. When the response of lipomata adjusted per unit cell (DNA) are compared to unaffected cells adjoining the tumor, an enhanced lipolytic respnse to microM concentrations of l-epinephrine is seen in both fragments and isolated cells. These findings indicate that diminished lipolysis cannot account for the exaggerated storage of neutral fat in these tumors.