Metabolism of Neoplastic Tissue. XV. Oxidation of Exogenous Fatty Acids in Lettré-Ehrlich Ascites Tumor Cells

Abstract

Lettré-Ehrlich ascites tumor cells were incubated in vitro in a phosphate saline medium with palmitate-1-C¹⁴, and its oxidation was measured by following the incorporation of radioactivity in respiratory CO₂. Regardless of whether the labeled fatty acid was present as plasma lipide, free palmitate, or as the serum-protein complex, it was oxidized readily at slightly less than linear rates over periods up to 4 hours. Oxidation of the 3 forms was greatly depressed by glucose, to a lesser extent by galactose, and only slightly by lactate and acetate. The data indicate that fatty acids are major substrates for tumor respiration, but their oxidation is partially spared when glucose is present in adequate concentration. These findings amplify and confirm previous conclusions based on studies of endogenous fatty-acid oxidation.