Smooth muscle cell (biliary tract)

**Smooth muscle cells in the biliary tract** compose the muscular layer of both the extrahepatic and intrahepatic bile ducts as well as the gallbladder wall[6][1]. These contractile cells regulate the storage, release, and downstream flow of bile in coordination with neurohormonal signals, notably cholecystokinin (CCK), which induces muscle contraction, and somatostatin, which inhibits it[3][5]. Smooth muscle activity is essential for normal bile ejection into the duodenum following a meal and is vital for digestive lipid absorption[4][3]. Pathological dysregulation—either hypo- or hyper-motility—can contribute to common biliary tract disorders such as gallstones and motility-related pain syndromes[5]. These cells are not considered a discrete molecular drug target (such as a receptor or enzyme) but rather a functional tissue population influenced pharmacologically by agents acting on their upstream regulators or ion channels. **Note:** - This entry does **not** represent a standard pharmacological target such as a protein receptor or enzyme and therefore is_incorrect: true. - The correct granularity for drug development is to specify a molecular entity, such as "Cholecystokinin receptor type A" or "L-type calcium channel (biliary smooth muscle)", not the cell type itself. **For structured drug target annotation, a molecular receptor or ion channel should be specified rather than "Smooth muscle cells in the biliary tract."**

Other names

Biliary tract smooth muscle cellSmooth muscle (bile duct/gallbladder)Gallbladder smooth muscle cell

Agonists (e.g., cholecystokinin): stimulate contraction of smooth muscle cell. Antagonists (e.g., somatostatin): inhibit contraction. Nitrates/calcium channel blockers: relax smooth muscle.