Effects of ursodeoxycholic acid therapy on in vitro gallbladder contractility in patients with cholesterol gallstones

During treatment with ursodeoxycholic acid (UDCA), the fasting gallbladder volume increases by a yet unknown mechanism. The present study tests whethe r in vitro human gallbladder contractility in response to acetylcholine and cholecystokinin is affected by UDCA therapy. Gallbladder tissue was obtain ed from 15 patients treated with UDCA (10 mg/kg/day) during three weeks pri or to surgery, and from 15 comparable patients not treated. Data were corre lated with in vivo contractility, bile composition, and gallbladder wall in flammation. The inflammation score was lower in the treated patient group. UDCA treatment enhanced gallbladder contractility in vitro: Dose-response c urves for acetylcholine and cholecystokinin were both shifted to the left, and the maximal contractile stress generated in response to cholecystokinin was higher in the treated group, whereas the maximal acetylcholine-induced stress was not increased. Maximal cholecystokinin-induced stress correlate d positively with fasting gallbladder volume and negatively with the biliar y cholesterol saturation index, but not with bile salt hydrophobicity or ga llbladder wall inflammation score. In conclusion, UDCA treatment improves i n vitro gallbladder contractility, possibly related to a reduced biliary ch olesterol saturation. Increased fasting gallbladder Volumes during UDCA tre atment thus do not appear to result from decreased gallbladder muscle contr actile strength.