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The Effects of CaNa2EDTA on Brain Lead Mobilization in Rodents Determined Using a Stable Lead Isotope Tracer

https://doi.org/10.1006/taap.1999.8725Get rights and content

Abstract

Studies have demonstrated the efficacy of CaNa2EDTA for reducing lead (Pb) levels in blood and soft tissues, including brain. However, a concern remains that a single dose of CaNa2EDTA may cause a significant increase in brain Pb levels due to a redistribution of endogenous Pb. Here we utilized a rodent model of Pb exposure in combination with a sensitive stable Pb isotope tracer methodology to assess the effects of CaNa2EDTA chelation treatment on the redistribution of Pb in brain, blood, kidney, and bone tissues. Thirty-two adult female albino rats (n = 6–7 animals/group) were exposed to 100 μg Pb/mL in drinking water for 4 weeks. Stable 204Pb tracer was administered via i.p. injection over 2 days prior to chelation. CaNa2EDTA was administered i.p. at a dose of 150 mg/kg/day for 1 to 5 days. Statistical differences were evaluated with univariate ANOVA. Under the Pb exposure and chelation treatment regimens utilized here, there was no evidence of a measurable redistribution of endogenous Pb (as total Pb or labile 204Pb tracer) into the brain after a single CaNa2EDTA dose. Further, CaNa2EDTA was not efficacious in measurably reducing brain or bone Pb levels, although brain levels of labile 204Pb tracer were significantly reduced after 5 days of chelation. CaNa2EDTA treatment was effective in significantly reducing both blood and kidney Pb levels. Overall, these data substantiate the efficacy of CaNa2EDTA for reducing soft tissue Pb levels, but not total brain Pb, and they do not support concern for a transient increase in brain Pb levels with treatment.

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