Effects of volatile fatty acids on propionate metabolism and gluconeogenesis in caprine hepatocytes.
Isolated caprine hepatocytes were incubated with fatty acids of various chain lengths. Short-chain fatty acids effects on rates of gluconeogenesis and oxidation from [2-14C]propionate were determined. Additions of glucose (2.5 mM) had no effect on hepatic [2-14C]propionate metabolism in the presence and absence of amino acids. A complete mixture of amino acids increased label incorporation from [2-14C]propionate into [14C]glucose by 22%. Butyrate inhibited [2-14C]propionate metabolism and increased the apparent Michaelis constant for [2-14C]propionate incorporation into [14C]glucose from 2.4 +/- 1.5 to 5.6 +/- .9 mM. Butyrate's effects on propionate were similar in the presence and absence of L-carnitine (1 mM). Isobutyrate, 2-methylbutyrate, and valerate (1.25 mM) had no effect on [14C]glucose production but decreased 14CO2 production to 57, 61, and 54% of the control [2-14C]propionate (1.25 mM). This inhibition on 14CO2 production was not competitive. Isovalerate had no effect on either [2-14C]propionate incorporation into glucose or CO2. An increase in ratio of [14C]glucose to 14CO2 from [2-14C]propionate demonstrated that short-chain fatty acids other than butyrate do not inhibit gluconeogenesis from propionate. In addition, fatty acids that generate a net synthesis of intracellular oxaloacetate may partition propionate carbons toward gluconeogenic rather than oxidative pathways in goat hepatocytes.
Aiello
R J
RJ
Department of Dairy Science, University of Wisconsin, Madison 53706.
Armentano
L E
LE
D000818:Animals; D002087:Butyrates / Q000494:pharmacology; D002331:Carnitine / Q000494:pharmacology; D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D005943:Gluconeogenesis / Q000187:drug effects*; D006041:Goats / Q000378:metabolism*; D066298:In Vitro Techniques; D058610:Isobutyrates; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011422:Propionates / Q000378:metabolism*; D014631:Valerates / Q000494:pharmacology
D002087:Butyrates; D005232:Fatty Acids, Volatile; D058610:Isobutyrates; D011422:Propionates; D014631:Valerates; C020380:isobutyric acid; C019475:2-methylbutanoic acid; D002331:Carnitine