engleski

Vitamin C supplementation and chelation therapy in lead-exposed rats

It has been proposed that ascorbic acid is a natural chelating agent capable to reduce lead retention, enhance lead elimination and increase effectiveness of chelating therapy in lead-exposed animals. Supplementation with ascorbic acid as a preventive dietary measure has been evaluated in lead-exposed population. However, results were inconsistent. The aim of this investigation was to evaluate the effect of ascorbic acid supplementation, alone or in combination with the lead chelator meso-dimercaptosuccinic acid (DMSA), on lead absorption and retention in growing rats concomitantly orally exposed to lead. Four to five-week-old female Wistar rats (from the Institute\'s breeding farm) were used in the experiment (N=75 ; 8-10 per group). L-ascorbic acid (daily dose 650 mg/kg or 25 mg/kg b. wt.) and/or DMSA (daily dose 91 mg/kg b. wt.) were administered by gavage during ongoing eight-day oral exposure to lead (as acetate ; daily dose 10 mg lead/kg b.wt.). On the ninth experimental day animals were killed by exsanguination from the abdominal aorta in ether anaesthesia. Lead concentrations in the blood, femur, liver, kidney and brain were analysed by electrothermal atomic absorption spectrometry. By supplementation with higher dose (650 mg/kg) of ascorbic acid, lead concentrations in the femur, liver, kidney and brain were increased (up to 130%). Lower dose (25 mg/kg) of ascorbic acid did not affect blood and tissue lead. Therapy with DMSA lowered lead concentrations in both blood and tissues (by 35 to 80%). Supplementation with ascorbic acid at higher dose markedly decreased DMSA efficacy, and lower dose did not affect DMSA chelation properties. In conclusion, ascorbic acid supplementation does not have beneficial effect on lead toxicokinetics in growing rats concomitantly exposed to lead. Furthermore, it even reduces DMSA efficacy when given at a high dose. These results suggest that special concern is necessary if ascorbic acid supplementation is considered during lead exposure, especially if DMSA therapy is in course.

Vitamin C; Chelation therapy; Lead; Rats

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