ARTIFICIAL BILE INHIBITS BILE SALT-INDUCED GALLBLADDER GLYCOPROTEIN RELEASE IN-VITRO

The more hydrophobic bile salts cause rapid release of preformed gallb ladder mucin and other glycoproteins by gallbladder explants in vitro, whereas the less hydrophobic bile salts elicit a lesser response. Thi s study was designed to determine (a) whether this short-term effect w as matched by a sustained increase in glycoprotein secretion over 24 h r and (b) whether it occurred when bile salts were presented in model biles rather than aqueous solution. Although 3 mmol/L taurodeoxycholat e in aqueous solution increased release of preformed gallbladder glyco protein to 843% of control values after 30 min incubation (p < 0.001), no significant increase was observed after 24 hr. The more prolonged exposure also reduced precursor uptake by 32% (p < 0.05) and inhibited synthesis of new glycoprotein by 24% (p < 0.05). Moreover, the stimul atory effect of taurodeoxycholate on release of gallbladder glycoprote in was much reduced when it was presented in model biles rather than i n aqueous solution. Nor was there any difference between the effects o f more hydrophobic vs. less hydrophobic bile salts when presented in m odel biles. Aqueous solutions of the more hydrophobic bile salts induc e a rapid release of gallbladder glycoprotein in vitro but do not prod uce a sustained increase in glycoprotein secretion. Their effect is li able to be prevented in vivo by interaction between bile salts and the other lipids in gallbladder bile.