Which statement about ASBT is true?

Which statement about ASBT is true?

• A. ASBT is located exclusively in the ileum
• B. ASBT reabsorbs bile acids in the colon
• C. ASBT is involved in reabsorption of bile acids in the ileum
• D. ASBT functions independently of sodium

Answer: (C)

ASBT is the apical sodium-dependent bile acid transporter that sits on ileal enterocytes and drives the reabsorption of bile acids from the intestinal lumen as part of enterohepatic circulation. This process is powered by the sodium gradient, meaning ASBT uses Na+ to bring bile acids into the cell. The main site of this reclamation is the ileum, which is why the statement about reabsorbing bile acids in the ileum is true. It’s not purely exclusive to the ileum (there is some expression elsewhere, such as in the kidney), and reabsorption in the colon is minimal compared to the ileum. It certainly does not function without sodium.

ASBT is the apical sodium-dependent bile acid transporter that sits on ileal enterocytes and drives the reabsorption of bile acids from the intestinal lumen as part of enterohepatic circulation. This process is powered by the sodium gradient, meaning ASBT uses Na+ to bring bile acids into the cell. The main site of this reclamation is the ileum, which is why the statement about reabsorbing bile acids in the ileum is true. It’s not purely exclusive to the ileum (there is some expression elsewhere, such as in the kidney), and reabsorption in the colon is minimal compared to the ileum. It certainly does not function without sodium.