Butyrate Metabolism in the Isolated, Perfused Goat Liver

Livers from nine healthy, mature goats were isolated and perfused for 1 hr via the portal vein, with blood containing a mixture of acetate, propionate, and butyrate in the approximate molar ratio of 9:3:1, respectively. Labeled substrates added to the blood were butyrate-l-C ~, butyrate-3-C ~, or succinate-l-C ~*. Concentrations of various blood and liver metabolites were determined at intervals during each perfusion. The C ~' content of each of these fractions Mso was measured. The liver consistently removed butyrate and propionate from the blood while blood levels of formate, lactate, glucose, and ketones increased. Carbon atoms one and three from butyrate were incorporated perdominantly into fl-hydroxybutyrate and CO~ with essentially no incorporation into lactate, propionate, or liver glycogen. The carboxyl carbon atom of succinate was recovered largely in C()~ and glucose. The ketogenic nature of butyrate in ruminant liver is thus confirmed.