It has been known that enterohepatic circulation of bile acids is essential for regular cycling of migrating motor complex (MMC). An important component of the enterohepatic circulation is the active reabsorption of conjugated bile acids in the terminal ileum, with special reference to bile acid pool size that may be defined as the total mass of bile acids in the enterohepatic circulation. However, because of technical difficulties in measuring of bile acid pool size in human being, the role of the bile acid pool has little been investigated, and the exact mechanism of change in bile acid pool size has not yet been clear. Therefore, were there two changes of small intestinal motility and bile acid pool size in cholesterol gallstone patients? and, if so, was there correlated relationship between both alterations require further investigation? METHODS Materials [3H] Taurocholic acid (radiochemical purity >97%; specific activity 129.5 GBq/mmol) was purchased from Perkin-Elmer Life Sciences (Boston, MA, USA). Scintillation liquid was obtained from Sigma-Aldrich (St. Louis, MO, USA). Animal and feeding procedures It has been known that enterohepatic circulation is bile acids is essential for regular cycling of migrating motor complex (MMC). An important component of the enterohepatic circulation is the active reabsorption of conjugated bile acids in the terminal ileum, with special reference to bile acid pool size that may be defined as the total mass of bile acids in the enterohepatic circulation. However, because of technical difficult in measuring of bile acid pool size in human being, the role of the bile acid pool has little been investigated, and the exact mechanism of, in there are two changes of small intestinal motility and bile acid pool size in cholesterol gallstone patients? and, if so, was there correlated relations between both alterations require further investigation? METHODS Materials [3H] Taurocholic acid (radiochemical purity> 97%; specific activity 129.5 GBq / mmol) was purchased from Perkin-Elmer Life Science s (Boston, MA, USA). Scintillation liquid was obtained from Sigma-Aldrich (St. Louis, MO, USA). Animal and feeding procedures