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Slow intestinal transit: A motor disorder contributing to cholesterol gallstone formation in the ground squirrel
Author(s) -
Xu Q,
Scott R B,
Tan D T,
Shaffer E A
Publication year - 1996
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510230650
Subject(s) - contractility , medicine , endocrinology , cholesterol , bethanechol , gallbladder , ileum , enterohepatic circulation , bile acid , jejunum , cholecystokinin , biology , chemistry , muscarinic acetylcholine receptor , receptor
Impaired gallbladder motility is an established factor in cholesterol gallstone formation. We assessed whether altered small intestinal smooth muscle contractility with slow transit might potentiate gallstone formation by further impeding enterohepatic cycling of bile acids. Ground squirrels were fed a 1% or a trace (controls) cholesterol diet. Small intestinal transit was evaluated from 51 Cr distribution in conscious, fasted animals 20 minutes after infusion into the proximal jejunum. Small intestinal and gallbladder smooth muscle contractility was determined in vitro . Biliary lipid secretion was measured from the cannulated common duct and the bile salt pool size calculated by isotope dilution. Gas‐liquid chromatography (GLC) assessed bile salt profile. In animals on the 1% cholesterol diet, aboral transit was significantly delayed, the maximal contractile response to bethanechol was markedly increased ( P <.05) with no change in median effective concentration in either circular or longitudinal muscle strips from both the jejunum and ileum, and the gallbladder contractile responses to bethanechol and cholecystokinin (CCK) were decreased. Cholesterol saturation index and the fraction of deoxycholic acid in the pool doubled, whereas the total bile salt pool size remained unchanged in cholesterol‐fed animals. In this model, a high‐cholesterol diet is associated with altered small intestinal smooth muscle contractility and prolonged small intestinal transit, in addition to diminished gallbladder contractility. The resulting sluggish enterohepatic cycling of bile salts, associated with expanded deoxycholate pool, contributes to cholesterol gallstone formation.