GALLBLADDER MOTILITY IN RESPONSE TO SHAM-FEEDING AND CHOLECYSTOKININ IN LEAN AND OBESE SUBJECTS

The risk of developing gallstones is increased in obese subjects. We h ave investigated whether gallbladder motility in obese subjects is dif ferent from that in lean control subjects. In 25 healthy non-diabetic obese subjects and 20 age- and sex-matched lean controls, fasting gall bladder volumes, gallbladder contraction in response to cephalic vagal cholinergic stimulation by modified sham feeding (MSF) and to hormona l stimulation with cholecystokinin (CCK) were studied. Gallbladder vol umes were measured during a 30-min MSF period followed 1 h later by a 1-hour continuous i.v. infusion of 0.5 IDU/kg ideal weight of CCK-33. Fasting gallbladder volumes were significantly (p < 0.001) larger in o bese (47 +/- 4 cm(3)) compared to lean subjects (24 +/- 2 cm(3)). Fast ing gallbladder volume was correlated with body mass index (p < 0.01). Gallbladder contraction during MSF was significantly (p < 0.01) reduc ed in obese (12 +/- 2%) compared to lean subjects (22 +/- 3%). CCK inf usion, leading to physiological post-prandial plasma CCK levels, induc ed a significantly (p < 0.001) greater absolute gallbladder contractio n in obese (27 +/- 3 cm(3)) compared to lean subjects (15 +/- 1 cm(3)) but the percentage gallbladder contraction was in the same range (64 +/- 3% vs. 67 +/- 4%, respectively). In addition, residual gallbladder volumes after CCK infusion were significantly (p < 0.001) larger in o bese (15 +/- 2 cm(3)) than in lean subjects (7 +/- 1 cm(3)). Two group s of obese subjects were identified: one with increased (> 40 cm(3)) a nd one with normal (less than or equal to 40 cm(3)) fasting gallbladde r volumes. Only obese subjects with increased fasting volumes showed a bnormal gallbladder motility.