Physical chemistry of biliary lipids during bile formation Article Conference Paper uri icon

Overview

MeSH Major

  • Caveolins
  • Cholesterol
  • Lipoproteins, HDL
  • Transcription Factors

abstract

  • Present concepts suggest that the canalicular secretion of bile salts is monomeric, which in turn drives the hepatic secretion of lecithin and cholesterol presumably as unilamellar vesicles into bile. As biliary lipids are concentrated within the biliary tree and gallbladder, bile salts structurally alter lecithin-cholesterol vesicles to form a variety of metastable aggregates whose structures and phase transformations are predicted by phase equilibria considerations. These structural transformations ultimately result in the dispersion of biliary lipids as thermodynamically stable micelles or micelles plus thermodynamically unstable vesicles in common duct and gallbladder biles. The experiments reviewed herein represent experimental simulations of these processes. We used pure aqueous lipid systems to model the putative stages of biliary lipid aggregation on the basis of interactions of small unilamellar vesicles of lecithin-cholesterol with bile salts as the latter's concentrations were varied from below to well above the critical micellar concentration. With submicellar bile salt concentrations likely to be found within hepatocytes, vesicle structures are not appreciably altered. However, perimicellar bile salt concentrations possibly occurring in canaliculi and bile ductules induce the formation of a hexagonal rodlike phase. On further increases in bile salt concentration, the hexagonal rods (formed from lecithin-rich and cholesterol-poor vesicles) are dissolved into mixed micelles as bile salt concentrations exceed their critical micellar concentrations. In slightly cholesterol-"supersaturated" biles, the rapid dissolution of this intermediate phase results in the formation of cholesterol-supersaturated mixed micelles that, in time, give rise to a new population of cholesterol-rich vesicles that coexist with saturated micelles.(ABSTRACT TRUNCATED AT 250 WORDS)

publication date

  • January 1990

Research

keywords

  • Conference Paper

Identity

PubMed ID

  • 2210642

Additional Document Info

start page

  • 143S

end page

  • 147S; discussion 147S-148S

volume

  • 12

number

  • 3 II