Characteristic features of antilipolytic activity of serum in relation to obesity.

Antilipolytic activity (ALA) of serum of the obese and controls was tested on rat epididymal adipose tissue incubated in medium containing adrenaline; the results were compared with the effect of insulin. Serum of the obese displayed lower ALA than controls, in one third obese individuals serum potentiated the effect of adrenaline. After fasting, ALA of serum decreased. ALA value is related to the prevailing metabolic situation, an inverse relationship was observed between ALA and levels of NEFA and ketone bodies. This seems to suggest that antilipolytic effect of insulin, whose concentrations are higher in the obese, is antagonised. This effect does not apparently depend on the presence of insulin antibodies, which do not inhibit, but, on the contrary, potentiated antilipolytic effect of insulin in vitro. Investigation of fractions of native serum proteins showed the effect of fraction 10 000--50 000 MW. to differ in the obese and controls. That particular fraction of sera of the obese had an adipokinetic effect.