Possible Glucogenicity of D(−)β-Hydroxybutyrate in Sheep

Abstract

FOR a number of years, considerable speculation has occurred on the possible glucogenicity of fatty acids containing an even number of carbon atoms. The evidence for and against net conversion of acetate and butyrate to carbohydrate in sheep has already been reviewed. Labelling patterns in glucose produced by sheep liver slices incubated with differentially labelled butyrate or acetate¹, and the distribution of radioactivity in plasma glucose following portal vein infusion of these acids², indicated that the tricarboxylic acid cycle is the major pathway for these conversions. These results, however, do not conclusively show the absence of a minor pathway which may have been masked. At present no information is available on the lactate–propanediol pathway³ in ruminant tissues, but it has been suggested⁴ that butyrate may be incorporated into glucose as a three carbon unit via this pathway.