Effect of some substances chemical on the crystallisation of calcium oxalate in vivo

Purpose: Epidemiological data collected during several decades that the majority of stones, up to 80% are composed of calcium oxalate (CaOx). This current study was aimed to look for an alternative treatment by using chemical substances on nephrolithiasic rabbits as a preventive against the development of urinary stone. The conditions of crystallisation and inhibition of oxalate calcium were studied at in vivo and in vitro. The experiment was conducted in normal and calcium oxalate (CaOx) nephrolithiasic abbits during three months. Several parameters were flowed every day including water intake, urinary volume and pH and crystalluria. Objectif: Our objective in this part of work was to determine the chemical inhibitors there act on the states of crystallization of calcium oxalate efficiently. A survey previous to the laboratory showed the in vitro inhibitory power of the chemical substances that we tested on the calcium oxalate. A comparison will be made between the two studies, only in the goal to confirm or to invalidate a possible effect of inhibition. The studied inhibitory substances are: the citric acid, Mg²*, Fe²*, F^-. Methods: XVc divided the rabbits aged of 1 mois with a middleweight of 960g in two groups of 6. The second group was considered like witnesses. The two groups are nourished in industrial food. Result: The inhibition capacity of Fluoride, citrate, ferric and Magnesium ion were important on the aggregation and size of oxalate calcium crystals, but didn't inhibit completely this crystalline species.

At maximal concentrations of 12 mM of fluoride ions inhibition was partial (89%). On the other hand, in the presence of citrate ion, the inhibition of calcium oxalate growth and aggregation increased. In fact at a concentration of 4 mM the inhibition percentage of oxalate calcium crystals was 54%. The addition of a concentration of 4 mM of ion ferric resulted in inhibition of 72% of calcium oxalate. On note that these ions developed an inhibition important enough at the lower concentrations. The same result has been found for Mg²⁺ ions, it acts was important on the nucleation phase.

In the comparison, in vitro study showed Fluoride ions acts on the phase of germination and aggregation with a rate of inhibition (73%). The citrate acts on the three phases of crystallization with a rate of inhibition of 96%. The ferric ions act on the phase of growth with a rate of 96%. The Mg²⁺ ion acts on the three phases of crystallization with a rate of inhibition of 90%.

Conclusion: The study showed to propose the following classification of the power inhibitory in vivo on the oxalate of calcium: Fluoride ions, Magnesium ions, Ferric ions, citric Acid. In vitro, the classification was reversed practically: Citric acid, Ferric, Magnesium, and Fluoride ions. These results obtained in vivo confirmed the beneficial effect of chemical inhibitors and may justify its use as a preventive agent against the formation of calcium oxalate urinary stones.

Keywords: inhibition, oxalate. rabbit, substances inhibitors, study