Utilisation of exogenous fatty acids by rat epididymal fat cells in vitro.

When isolated rat fat cells are incubated with radioactively labelled palmitate the extracellular fatty acid pool is diluted by fatty acids of endogenous origin. Using fat cell concentration as an experimental variable, a simple graphical procedure has been devised to correct for the difficulty such precursor dilution causes in measurement of oxidation and esterification of exogenous fatty acids. After application of such corrections it was calculated that extracellular palmitate was utilised for oxidation with a composite Km of approx. 7 mu M. The composite Km for palmitate esterification was 29 mu M (no other substrates present, albumin included 1t 10 mg/ml).