title: Glucose alleviates ammonia-induced inhibition of short-chain fatty acid metabolism in rat colonic epithelial cells.
abstract: Ammonia decreased metabolism by rat colonic epithelial cells of butyrate and acetate to CO2 and ketones but increased oxidation of glucose and glutamine. Ammonia decreased cellular concentrations of oxaloacetate for all substrates evaluated. The extent to which butyrate carbon was oxidized to CO2 after entering the tricarboxylic acid (TCA) cycle was not significantly influenced by ammonia, suggesting there was no major shift toward efflux of carbon from the TCA cycle. Ammonia reduced entry of butyrate carbon into the TCA cycle, and the proportion of CoA esterified with acetate and butyrate correlated positively with the production of CO2 and ketone bodies. Also, ammonia reduced oxidation of propionate but had no effect on oxidation of 3-hydroxybutyrate. Inclusion of glucose, lactate, or glutamine with butyrate and acetate counteracted the ability of ammonia to decrease their oxidation. In rat colonocytes, it appears that ammonia suppresses short-chain fatty acid (SCFA) oxidation by inhibiting a step before or during their activation. This inhibition is alleviated by glucose and other energy-generating compounds. These results suggest that ammonia may only affect SCFA metabolism in vivo when glucose availability is compromised.
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA 94720-3104, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Cremin
authors.forename: Mark D
authors.initials: MD
authors.lastname: Fitch
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Fleming
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000085:Acetates / Q000378:metabolism; D000641:Ammonia / Q000494:pharmacology*; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002087:Butyrates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002952:Citric Acid Cycle / Q000187:drug effects / Q000502:physiology; D003065:Coenzyme A / Q000378:metabolism; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007657:Ketone Bodies / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D014233:Tricarboxylic Acids / Q000378:metabolism
chemical_list: D000085:Acetates; D002087:Butyrates; D004232:Diuretics; D005232:Fatty Acids, Volatile; D007657:Ketone Bodies; D011422:Propionates; D014233:Tricarboxylic Acids; D000643:Ammonium Chloride; D002245:Carbon Dioxide; D000641:Ammonia; D005947:Glucose; D003065:Coenzyme A; D020155:3-Hydroxybutyric Acid