Partial and incomplete oxidation of palmitate by cultured beating cardiac cells from neonatal rats

The discrepancy in the rate of [14C]O2 formation from either [1-14C]- or [16-14C]palmitate is demonstrated and could be explained by the preferential formation of L-(+)-3-hydroxybutyrate from the four carbon atoms at the omega terminus. The identity of this product as L(+)-3-hydroxybutyrate was established and shown to be the major component of the radioactive products in the extracellular medium from palmitate based on (a) ion-exchange chromatographical properties, (b) gas-liquid chromatography, (c) mass spectrometric analysis, (d) stereoisomeric separation, and (e) its very low rate of utilization by the cells. We therefore propose a shunt to the oxidation of palmitate in these cells occurring at the stage of L(+)-hydroxybutyryl-CoA which undergoes deacylation causing the product to be transported outside the cell.