Effect of Lead on Globin Synthesisin Vitro

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Abstract
Ali, M. A. M., and Quinhin, A., Effect of lead on globin synthesis in vitro. Am J Clin Pathol 67: 77–79, 1977. A defect in heme synthesis is well documented to occur in lead intoxication. Globin synthesis and the α/β globin chain synthesis ratio have been shown to be disturbed in lead poisoning. To elucidate further the nature of the inhibitory effect of lead on hemoglobin synthesis, reticulocyte-rich peripheral blood samples have been incubated with lead at concentrations of 10−6, 10−5, and 10−4 M, equivalent to 20, 200, and 2,000 μg/dl (.96, 9.6 and 96.0 μmol/l), respectively. The incorporation of tritiated leucine into globin was determined. Globin chain synthesis decreased to 85, 49, and 15% of the control value with increasing lead concentrations. The effect of heme on inhibition of globin synthesis by lead was studied by incubating reticulocyte-enriched blood with lead 10−5 M (200 μg/dl; 9.6 μmol/l) in the presence or absence of heme at a concentration of 10 3 M. Lead alone depressed the incorporation of tritiated leucine to 45% of control, while globin synthesis with heme alone was 109% of control. Although in the presence of both heme and lead, the mean incorporation of leucine into globin was 69.2% of control, the increase was not significantly different from that obtained with lead alone. It is concluded that (1) lead has an inhibitory effect on globin synthesis at a concentration considered to be within the acceptable range encountered in environmental lead pollution, and the extent of inhibition is dose-dependent; (2) the effect of lead on globin synthesis is not significantly prevented by heme and, therefore, does not appear to be mediated through the well-documented inhibitory effect of lead on heme synthesis.