Abstract
Perturbations in intracellular Ca homeostasis, produced by Pb at low concentrations, may be an unifying hypothesis to explain Pb toxicity at the cellular level. Such perturbations may place the regulation of cellular processes out of the physiological range of normal control through changes in cytosolic free Ca concentration. The present study was undertaken to characterize more fully Ca:Pb ratios in different structural compartments of OC. Bone cells, enriched for OC, were prepared by a collagenase digestion of murine calvaria. After OC grew to confluence in 7 days, intracellular Ca:Pb ratios were calculated using kinetic analyses of dual label 45Ca and 210pb washout curves by desaturation techniques that employed a validated 3 compartment model. The ratio of Ca:Pb half-times and rate constants were <4 thereby indicating similar intracellular pathways for these two metals. However, the kinetic distribution of Ca and Pb in OC was not symmetrical; the Ca:Pb ratio for two rapidly exchanging compartments was 40:1; for the most slowly exchanging compartment, which includes mitochondrial Ca and Pb, the Ca:Pb ratio was 7:1. The Ca:Pb ratios for the steady state flux across the plasma membrane was 35:1; and the ratio was 30:1 across the mitochondrial membrane. These observations reveal both similarities and differences in the intracellular homeostasis of Ca and Pb in OC. These quantitative relationships should be considered for the evaluation of Pb effects on intracellular Ca homeostasis and Ca functions in OC, other cell types and in cell-free systems.
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Rosen, J., Pounds, J. LEAD (Pb)–CALCIUM (Ca) INTERACTIONS IN CULTURED OSTEOCLASTIC BONE CELLS (OC). Pediatr Res 21 (Suppl 4), 346 (1987). https://doi.org/10.1203/00006450-198704010-01072
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DOI: https://doi.org/10.1203/00006450-198704010-01072