Effect of different experimental conditions on lipogenesis and substrate oxidation in isolated adipocytes from fattening Holstein steers

The present study was undertaken to provide further information on lipogenesis in isolated adipocytes from the subcutaneous adipose tissue of fattening steers. The main aims were to compare different incubation media and to clarify the effects of fetal bovine serum (FBS) on lipogenesis and substrate oxidation rate in the adipocytes. The isolated adipocytes were prepared by the collagenase digestion technique. The changes in cellularity, the incorporation rates of acetate or glucose into lipid molecules, and the oxidation rates to CO₂ both in fresh and preincubated adipocytes were measured in different media. It was shown that FBS increased significantly both lipogenesis and the oxidation rates of glucose or acetate in the fresh adipocytes but insulin did not. In isolated adipocytes preincubated for 24 and 48 h, the cellularity, the incorporation rate of glucose into lipid molecules, and the oxidation rates of glucose or acetate to CO₂ were not different to those in fresh adipocytes, but the incorporation rate of acetate into lipid molecules was significantly lower.