Alimentary production of gallstones in hamsters. 11. Relation between diet and composition of the bladder bile 1

Age, sex and source of hamster affect experimental cholesterol cholelithiasis

In the present study, we examined the effect of the following factors on a hamster model of cholesterol cholelithiasis: (i) the source of the golden Syrian hamsters (Sasco, Omaha, NE or Charles River, Wilmington, MA), (ii) the sex of the experimental animals and (iii) their age (4 wk vs. 8 wk of age). All hamsters were fed a semipurified diet which contained cholesterol (0.3%) and palmitic acid (1.2%). No cholesterol gallstones formed in any of the female hamsters regardless of age or source. The 4-week-old male hamsters from Sasco had the greatest incidence of gallstones (93%). The 8-week-old male hamsters tended to have a lower incidence of cholesterol gallstones than the younger ones, regardless of the commercial supplier (67 vs. 93% for Sasco and 27 vs. 40% for Charles River). Female hamsters had higher liver and serum cholesterol levels than the male hamsters; Charles River hamsters had lower serum cholesterol concentrations than the Sasco animals. Total biliary lipid concentrations were highest in Sasco male hamsters, but biliary cholesterol (mol%) was lower in the males than in the females (4.2-4.5% vs. 6.1-7.1%) regardless of age. The cholesterol saturation indices were higher in the Sasco females than the corresponding males; these values were lower in the Sasco hamsters than the Charles River animals, regardless of age or sex. The male Sasco hamsters had a higher total biliary bile acid concentration (98.9 mg/mL) than the Sasco females (58.9 mg/mL) and the Charles River animals (24.6 mg/mL for males and 38.2 mg/mL for females). The percentage of chenodeoxycholic acid in bile was significantly lower, and the percentage of cholic acid was higher in all females as compared to males.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for a nucleation defect in bile from gallstone patients

When modern methods of estimating cholesterol saturation in bile were first applied to human bile samples, it seemed that a clear distinction could be made between normal and abnormal biles on the basis of cholesterol saturation. Supersaturation of bile with cholesterol appeared to be the only critical defect required for stone formation. A variety of evidence has now accumulated which indicates that a nucleation defect is also important. Chief among these observations is the fact that gallbladder bile from stone patients nucleates cholesterol crystals more rapidly than equally saturated gallbladder bile from controls. To determine whether the gallbladder contributes to the nucleation defect, hepatic and gallbladder bile nucleation times have been compared. Although the former is more supersaturated, the latter nucleates faster suggesting that the gallbladder is important. In another study, the nucleation times of crystal-free abnormal bile, normal bile and a mixture of the two were obtained. The mixture nucleated as rapidly as the abnormal bile even when the abnormal bile contributed only 5% of the volume of the mixture. This indicated that a nucleating factor is added to abnormal bile in the gallbladder.

Morphological changes of the small-intestinal mucosa of guinea pig and hamster following incubation in vitro and perfusion in vivo with unconjugated bile salts

Incubation in vitro of the intestine of the hamster and guinea pig with 5 mM sodium cholate and with 2 mM sodium deoxycholate and sodium chenodeoxycholate resulted in significant morphological changes compared with control incubations. Generally, no major differences were observed between proximal and distal small intestine or between the species used. Only when guinea pig intestine was incubated with 5 mM cholate was less damage found proximally than distally. Perfusion in vivo of the intestine of the hamster and guinea pig with Krebs-Ringer phosphate results in separation of the epithelium from the lamina propria without excessive shedding of epithelial cells from villous tips. This change was also seen in specimens taken before perfusion and probably represents unavoidable trauma during handling of the intestine. In contrast to studies in vitro, regional differences are readily demonstrable with perfusion of bile salts in vivo. Dihydroxy bile salts produce more marked alterations of both proximal and distal small intestine than the trihydroxy bile salt, sodium cholate. Dihydroxy bile salts result in significantly greater alterations in proximal than in distal mucosa. When 5 mM cholate at pH 6.8 is perfused in the guinea pig, absorption occurs approximately 30 times more rapidly from distal than from proximal segments, while in proximal segments 2 mM chenodeoxycholate is absorbed approximately 15 times more rapidly than 5 mM cholate. A correlation is suggested between the morphological alteration produced in the region of the small intestine by a bile acid and the amount of bile salt passing through the cell. Furthermore, it is proposed that the ileal cells may be damaged to a lesser extent by bile acids normally found in that particular species.