Metabolism of Octanoate and Its Effect on Glucose and Palmitate Utilization by Isolated Fat Cells

Summary Octanoate is avidly incorporated into triglycerides by isolated rat adipocytes in the presence of glucose via direct esterification without prior β-oxidation to acetyl CoA. This was shown by separation of the products formed from [1-14C] octanoate into lipid classes using Florisil columns, and after alkaline hydrolysis of the triglyceride fraction, by cochromatography with authentic fatty acids on reverse-phase Celite columns. The relative contribution of [U- 14 C] glucose and [1- 14 C] octanoate to triglyceride synthesis and CO2 formation were studied under a variety of conditions. Concentrations of octanoate below 0.5 mM have a stimulatory effect on the conversion of [U- 14 C] glucose to CO2, triglycerides and esterified fatty acids. However, a marked depression of fatty acid synthesis from [U- 14 C] glucose was observed in the presence of millimolar concentrations of octanoate. Octanoate had no effect on the esterification of palmitate, but palmitate strongly depressed the ability of rat adipocytes to esterify octanoate.