title: The influence of hydroxyapatite and pyrophosphate on the formation product of calcium oxalate at different pHs.
abstract: The nucleating effect of hydroxyapatite (HAP) and the inhibitory effect of pyrophosphate (PPi) on calcium oxalate crystallization have been studied at different pH's in solution metastabely supersaturated with respect to calcium oxalate but saturated with respect to HAP. Crystallization was monitored by a decrease of calcium in the supernatant and formation products were calculated. At a pH above 6.0 already minimal HAP concentrations proved to be a suitable substrate for heterogeneous nucleation and growth of calcium oxalate. PPi showed a pronounced inhibitory effect on spontaneous as well as on HAP induced crystallization of calcium oxalate, this effect being highly pH dependent. HAP was found to neutralize the inhibitory effect of PPi in a molar ratio of 10:1.
authors.affiliation: Division of Urology and Stone Research Laboratory, Regional Hospital, Biel, Switzerland.
authors.forename: J M
authors.initials: JM
authors.lastname: Baumann
authors.forename: D
authors.initials: D
authors.lastname: Ackermann
authors.forename: B
authors.initials: B
authors.lastname: Affolter
mesh_terms: D002129:Calcium Oxalate; D003460:Crystallization; D011756:Diphosphates / Q000494:pharmacology*; D017886:Durapatite; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000494:pharmacology*; D066298:In Vitro Techniques; D014545:Urinary Calculi / Q000209:etiology
chemical_list: D011756:Diphosphates; D006882:Hydroxyapatites; D002129:Calcium Oxalate; D017886:Durapatite