Negative feedback regulation of the ileal bile acid transport system in rodents

摘要: Abstract Background: Active transport of conjugated bile acids by ileal enterocytes is a key mechanism for conservation the acid pool. Experiments were performed to determine whether such regulated substrate load. Methods: Using anesthetized biliary fistula guinea pigs or rats, ileum was perfused with ursodeoxycholyltaurine at concentration causing maximal this acid; absorption assessed recovery. Before perfusion, animals ingested one three diets: chow, chow added acid, cholestyramine. Results: In pig, ingestion taurocholate-enriched diet resulted in 75% decrease rate ursodeoxycholyltaurine. Similar results obtained cholylsarcosine (a deconjugation-dehydroxylation resistant analogue) chenodeoxycholylglycine, endogenous pig. contrast, cholestyramine caused an increase absorption. rat, cholyltaurine also decreased transport. down-regulation active occurred after 2–3 days feeding; up-regulation required 3–4 days. Conclusions: Bile metabolism feedback inhibition addition well-established biosynthesis liver. Together, these two regulatory mechanisms ensure constancy secretion.