Effect of epinephrine on the synthesis of glyceride glycerol in adipose tissue in vitro.

In order to study the effect of epinephrine on the rate of esterification of fatty acids in adipose tissue, pieces of epididymal fat pad were incubated in KRB in the presence of purified albumin, glucose and either 1-14C-glycerol, 1-14C-glucose or 6-14C-glucose. Epinephrine enhances the production of glycerol but reduces the uptake of 1-14C-glycerol by the tissue and its conversion to 14CO2, 14C-fatty acids and 14C-glyceride glycerol. When the change in specific activity of the tracer is taken into account the effect of epinephrine on the utilization of glycerol by the tissue is only observed in the reduction of glyceride glycerol synthesis. When 14C-labelled glucose was used as tracer, epinephrine enhances both the production of 14CO2 from 6-14C-glucose and the synthesis of 14C-glyceride glycerol from 1-14C and 6-14C-glucose. The contrasting effects of epinephrine on the glyceride glycerol formation from glycerol and from glucose can explain the difficulties found in observing any change in the net rate of esterification of fatty acids by adipose tissue.