EFFECT OF BETA-CYCLODEXTRIN DIETARY SUPPLEMENTATION ON BILIARY PROTEINS AND THEIR RESULTING CHOLESTEROL NUCLEATING ACTIVITY IN PIGS

We explored the possibility that the biliary protein fraction may supp ort part of the variation in the nucleating activity previously measur ed in gallbladder biles of pigs. Eighteen gallbladder aspirates freshl y obtained from three dietary groups (0, 5, or 10% beta-cyclodextrin) of six pigs were chromatographed to purify their total protein fractio n. Proteins were quantified, and analysed through electrophoresis and immunoblotting or enzyme-linked immunosorbent assay for albumin, and f ive putative effecters of cholesterol crystallisation, mucins, immunog lobulin A, 130 kDa, apolipoprotein A-I, and anionic polypeptide fracti on. Each total protein fraction was also assayed for its ability to in fluence cholesterol precipitation, when added to supersaturated model bile. The current data provided evidence that the cholesterol crystall isation-promoting activity of biliary proteins in model biles increase d with the beta-cyclodextrin dietary content. This occurred without an y significant change in the total biliary protein content, but was ass ociated with a significant decrease in the concentration of albumin an d apolipoprotein A-I, resulting in changes in the overall balance of p roteins in bile. Comparison of these results with the crystallisation figures previously obtained from the corresponding native biles led us to conclude that biliary proteins might influence the outcome of the crystallisation process, namely the final crystal concentration at equ ilibrium, but would not systematically represent a major driving force for determining the velocity of crystal formation in native bile of p igs. (C) 1998 Published by Elsevier Science B.V. All rights reserved.