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.