Dialysis of gallbladder bile. Correlation between rates of exit of bile salts and bilirubin from the dialysis sac.

Twenty-six gallbladder bile samples were dialyzed against an infinite dilution of Tris buffer at pH 7.4. Bilirubin moved out of the dialysis sac at a rate slower than that of bile salts. The rates of exit of these two molecules showed a significantly positive correlation with each other and a significantly negative correlation with bile salts concentration. Phospholipids and cholesterol did not move out of the dialysis sac. These data are consistent with the assumption that bile is a mixed micellar solution of bile salts, phospholipids, and cholesterol and suggest an association between bilirubin and the mixed micelle.