Absorption and metabolism of the volatile fatty acids in the hind-gut of the rabbit.

Volatile fatty acids (VFA) absorption in the large intestine of the anaesthetized rabbit was evaluated by measuring variations in the concentration of VFA in intestinal loops and plasma arteriovenous differences. Metabolic conversions were studied using [1-14C]acetate, [1-14C]propionate and [3,4-14C]butyrate. The hind-gut tissues metabolized the three VFA, although this metabolism varied with the segment studied. Butyrate was the best respiratory fuel for the colonic wall, followed by propionate; acetate participated also, but it was mainly converted to glutamate. The liver was the main organ metabolizing absorbed propionate and butyrate; acetate was available for extrahepatic tissue metabolism. For the rabbit, VFA represented about 40% of the maintenance energy requirement.