Effect of lead intoxication on calcium homeostasis and calcium-mediated cell function: a review.

The interaction between lead and essential metals is a complex, well recognized, but poorly understood phenomenon. Dietary deficiencies or excesses of certain essential metals may alter the absorption, elimination, or dose response of lead. Lead, in turn, may alter the homeostasis and function of essential metals. This review will be limited to the effect of lead on calcium, an essential metal with elaborate systemic and cellular homeostatic mechanisms and innumerable second messenger and coupling-factor functions. Lead may ultimately perturb calcium-regulated or calcium-mediated functions (a) directly by interfering with calcium transport or storage processes, e.g., Ca2+ transport proteins, calcium gates, etc.; (b) indirectly by altering cell functions required for calcium homeostasis, e.g., energy production, plasma membrane permeability, etc.; (c) by substitution of Pb2+ for Ca2+ at functionally important calcium binding sites, e.g., calmodulin. While any individual study may not provide adequate experimental verification of the causal role of perturbations of calcium metabolism and function as the primary toxic lesion of lead intoxication, the collective observations of many studies do strongly support lead-calcium interactions as an important functional lesion in lead intoxicated organelles, cells, tissues, and organ systems.