Interrelationships between the metabolism of short-chain fatty acids by ruminant liver slices

Abstract

The metabolism of acetate, propionate, butyrate and isobutyrate by liver slices from starved sheep were investigated. The 14C from carboxyl-labeled acetate and carboxyl-labeled butyrate was found in carbon dioxide, protein and lipids. No 14C could be recovered in ketone bodies. When labeled propionate was used, 14C was found in carbon dioxide, glucose, protein, succinate, malate and fumarate, but the amount of 14C recovered in lipids was negligible. Propionate inhibited the conversion of acetate to carbon dioxide, but the metabolism of propionate was stimulated by presence of either acetate or glucose. The presence of butyrate caused a marked stimulation in the metabolism of propionate but depressed the metabolism of acetate. Propionate had no effect on butyrate metabolism. Citrate stimulated the metabolism of butyrate but not propionate. Evidence was presented to show that it was unlikely that the stimulatory effect of butyrate on propionate metabolism could be explained on the basis of energy contributions from butyrate.