Glycochenodeoxycholic acid inhibits calcium phosphate precipitation in vitro by preventing the transformation of amorphous calcium phosphate to calcium hydroxyapatite

Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxy...

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Bibliographic Details
Published inThe Journal of clinical investigation Vol. 88; no. 4; pp. 1265 - 1271
Main Authors SUI-MIN QIU, GARY WEN, HIRAKAWA, N, SOLOWAY, R. D, NAN-KANG HONG, CROWTHER, R. S
Format Journal Article
LanguageEnglish
Published Ann Arbor, MI American Society for Clinical Investigation 01.10.1991
Subjects
Biological and medical sciences
Calcium - analysis
Calcium Phosphates - chemistry
Chemical Precipitation
Digestive system
Durapatite
Fourier Analysis
Glycochenodeoxycholic Acid - pharmacology
Hydroxyapatites - chemistry
Medical sciences
Micelles
Pharmacology. Drug treatments
Taurocholic Acid - pharmacology
Bile acid conjugate
Chemotherapy
Calcium
Calcium calculus
Hydroxyapatite
In vitro
Biological activity
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Summary:Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxycholic acid inhibits calcium hydroxyapatite formation. Glycochenodeoxycholic acid (2 mM) totally inhibited transformation of amorphous calcium phosphate microprecipitates to macroscopic crystalline calcium hydroxyapatite. This inhibition was not mediated by decreased Ca2+ activity. Taurocholic acid (2-12 mM) did not affect hydroxyapatite formation, but antagonized glycochenodeoxycholic acid. Both amorphous and crystalline precipitates contained a surface fraction relatively rich in phosphate. The surface phosphate content was diminish by increasing glycochenodeoxycholic acid concentrations, and this relationship was interpreted as competition between bile acid and HPO4(-4) for binding sites on the calcium phosphate surface. A phosphate-rich crystal surface was associated with rapid transition from amorphous to crystalline states. These results indicate that glycochenodeoxycholic acid prevents transformation of amorphous calcium phosphate to crystalline hydroxyapatite by competitively inhibiting the accumulation of phosphate on the crystal embryo surface.
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ISSN:0021-9738
1558-8238
DOI:10.1172/jci115430