Elsevier

Environmental Research

Volume 72, Issue 1, January 1997, Pages 45-55
Environmental Research

Regular Article
Lead–Calcium Interactions: Involvement of 1,25-Dihydroxyvitamin D,☆☆

https://doi.org/10.1006/enrs.1996.3689Get rights and content
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Abstract

Interactions between dietary calcium (Ca) and lead (Pb) which influence serum levels of the vitamin D hormone, 1,25-dihydroxyvitamin D (1,25(OH)2D), intestinal Ca and Pb absorption, and body Pb retention were investigated in chicks. In a 5 × 5 (levels of Ca and Pb) design, response surface modeling was used to describe and compare the various interactions. Lead ingestion and Ca deficiency alone or in combination generally increased serum 1,25(OH)2D levels over most of the range of dietary Ca and Pb. However, in severe Ca deficiency, Pb ingestion resulted in marked decreases in hormone concentration. Overall similarities in response profiles for 1,25(OH)2D, intestinal Ca absorption and calbindin-D suggest that major interactions between Pb and Ca are mediated via changes in circulating 1,25(OH)2D concentration, rather than direct effects on the intestine. The response profiles for Ca and Pb absorption differed, in part, suggesting that intestinal transport of the two cations may not be identical. Kidney and bone Pb content also differed in response to varying Ca and Pb levels, providing evidence for additional tissue-specific interactions not related to 1,25(OH)2D. The present study provides a comprehensive basis on which to interpret the results of previous clinical and experimental results.

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This work was supported by NIH Grant ES04072. Cornell University is fully accredited by the A.A.A.L.A.C. and all experiments were conducted in accordance with the N.I.H.Guidelines for Care and Use of Experimental Animals.

☆☆

K. R. Mahaffey, Ed.