Effect of cholestyramine particle size on in vitro binding of conjugated bile salts.

Abstract

SummaryCholestyramine (50-75 μ in diameter) was incubated with graded levels of taurocholate, glycocholate, taurodeoxycholate, or glycodeoxycholate in 0.3 M phosphate buffer. The resin showed a preference for taurine conjugates over glycine conjugates and dihydroxy bile salts over trihydroxy bile salts. Decreasing resin particle size to 10-30 μ in diameter permitted a more rapid saturation of the resin's binding sites with dihydroxy bile salt but did not affect binding of trihydroxy bile salt.Reducing particle size of cholestyramine or a similar anion-exchange resin did not affect bile salt binding from swine and human gallbladder bile. The findings suggest that bile salts are bound by resins in the monomer rather than micellar form, and sieve exclusion of bile salt micelles by the resin matrix does not impede the binding process. Each of the resins preferentially bound the taurine-conjugated bile salts in human bile.