INHIBITION BY HUMAN SERUM OF THE ADIPOKINETIC EFFECT OF A HUMAN PITUITARY LIPID-MOBILIZING FACTOR

Abstract

A lipid mobilizing factor (LMF) with an adipotrophic effect in man and animal adipose tissue has been prepared from human pituitary glands. In vitro studies have demonstrated that the lipolytic effect was dependent on the albumin used in the incubation medium. Two of the six albumins studied depressed the release of non-esterified fatty acids from human fat pads. Polyacrylamide gel disc-electrophoresis demonstrated the presence of contaminations in purchased serum albumins. They were eliminated by DEAE-cellulose chromatography, which gave one fraction that inhibited the adipokinetic effect of LMF, and a more homogeneous albumin fraction. In vitro lipolysis in rabbit as well as in human fat pads occurred more readily in the media containing purified serum albumin than in media with purchased serum albumin. It was concluded that in vitro lipolysis gives comparable results when studied in media containing the same batch of serum albumin only. Furthermore an agent should not be claimed to be non-lipolytic until it has been assayed in several, preferably homogeneous serum albumin media.