[Changes in bile components during the formation and prevention of black pigment gallstone in a guinea pig model]

Black pigment gallstones were found in 22 out of 23 guinea pigs one week after the common bile ducts were partially ligated (S group). The incidence decreased to 11/20 (P less than 0.01) if the animals were fed with a chow containing bile salt mixture, glucurolactone, ane aspirin (S+M group). Three weeks after the ligation the incidence of gallstone in S group and S+M group was 17/18, and 9/10, respectively (P greater than 0.05). Glucuronidase (beta-G) activity in the bile of S group was not higher than that of control group (C group, P greater than 0.05), and all the bile samples were sterile. The biliary concentrations of ionized calcium (ICa), unconjugated bilirubin (UCB), total calcium (TCa), total bilirubin (TBr), glycoprotein (GIy. P), and PH significantly fluctuated among guinea pig groups and were parallel to gallstone incidence. The results of this study could hardly be explained by Maki beta-G theory, but were consistent with the assumption that the precipitation-dissolution equilibrium of calcium bilirubinate is the key of pigment gallstone formation, thus the increases of the above mentioned bile components, including beta-G activity, would bias this equilibrium towards calcium bilirubinate precipitation and therefore promote gallstone formation. On the contrary, stone formation would be prevented.