The metabolism of short-chain fatty acids in the sheep. 2. Further studies with rumen epithelium

Abstract

The rate of metabolism of propionic acid by sheep-rumen epithelium increased with the proportion of CO2 in the atmosphere up to about 20% CO2/80% 02. This level of CO2 had no influence on metabolism rate of acetic or butyric acid. Malonate inhibited uptake of each acid without showing any differential action on formation of ketone bodies from butyrate. Malonate inhibition of propionate uptake was only partially reversed by fumarate. Succinate was produced when propionate was metabolized in the presence of malonate. Ammonium ion inhibited metabolism of propionate and possibly of acetate, but not of butyrate. It had no appreciable effect upon ketogenesis. Propionate depressed the O2 uptake of rumen epithelial tissue in the absence of CO2, but stimulated respiration in the presence of the latter. Butyric acid and glucose increased rate of O2 uptake. The uptake of acetic, propionic and butyric acids, and production of ketone bodies by ox rumen epithelium paralleled that of the corresponding tissue of the sheep.