Effects of hydrophobic and hydrophilic bile salts on gallstone growth and dissolution in model biles.
Cholesterol crystallization is a prerequisite for gallstone formation and growth, whereas dissolution of crystallized cholesterol forms the basis of nonsurgical therapy. Crystallization has been studied in detail, but dissolution mechanisms and effects of gallstones are largely unknown.


METHODS
We evaluated gallstone growth or dissolution, cholesterol crystallization and lipid distribution into various phases, in model biles with low or intermediate phospholipid contents (crystal-containing left two-phase or central three-phase zones), and with high phospholipid or low cholesterol contents (crystal-free right two-phase or bottom one-phase zones).


RESULTS
In model biles with added gallstones plotting in left two-phase and central three-phase zones, gallstone masses increased, whereas crystallization in the aqueous phase was less than without gallstones (P<0.001). In biles plotting in the right two-phase zone, gallstone masses decreased, depending on bile salt hydrophobicity (TUDC>TC>TCDC: P<0.001). In biles plotting in the bottom one-phase zone containing TC or TCDC, gallstone masses increased. In contrast, gallstone masses decreased in case of TUDC with preferential distribution of cholesterol into emerging vesicles.


CONCLUSIONS
Our findings suggest competition between gallstone surface and surrounding aqueous phase for precipitation of cholesterol in crystal-containing zones. Different gallstone dissolution mechanisms may exist for TUDC and TCDC.
Venneman
Niels G
NG
Gastrointestinal Research Unit, Departments of Gastroenterology and Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
van Kammen
Marieke
M
Renooij
Willem
W
Vanberge-Henegouwen
Gerard P
GP
van Erpecum
Karel J
KJ
D001646:Bile / Q000737:chemistry* / Q000378:metabolism; D001647:Bile Acids and Salts / Q000737:chemistry* / Q000378:metabolism; D002769:Cholelithiasis / Q000737:chemistry / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D042882:Gallstones / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical
D001647:Bile Acids and Salts; D002784:Cholesterol