EFFECT OF CHRONIC LEAD POISONING ON ERYTHROCYTE PROTOPORPHYRIN IN RATS

Research has shown that exposure to lead may have adverse effects at different blood lead concentrations. Lead inhibits at least two enzymes that are essential for the formation of heme, and because of the interaction of lead with these enzymes, no iron is inserted into protoporphyrin. Therefore the concentration of protoporphyrin increases in erythrocytes. The concentration of lead was measured by atomic absorption at 217.0 nm. The erythrocyte protoporphyrin was determined following extraction into 90% ethanol. The concentration of protoporphyrin in the blood of the lead exposed rat group was increased compared to that in the control group [12.46 +/- 0.57 (mean +/- S.D., n= 72) vs. 3.89 +/- 0.42, n=68, µmollL, p<0.05]. The assay had excellent precision for both control and lead exposed groups (intra-assay and interassay coefficient of variation<5%). The method was linear from 0.0 to 12.46 µmollL of erythrocyte protoporphyrin. A good relationship was obtained between erythrocyte protoporphyrin value and blood lead concentration. The results suggest that the erythrocyte protoporphyrin value obtained by this method could be used as a screening test for lead poisoning