[Effects of lead on the protein of erythrocyte membranes]

In order to study the effects of lead in the circulating peripheral blood on the erythrocyte membrane, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of protein in the erythrocyte membrane was performed in 28 men exposed to lead in a scrap lead refining factory and 18 men working in railway construction as the controls. Furthermore, in order to corroborate the effects in vitro experiments by SDS-PAGE of protein in the mixture of human erythrocyte membranes with added lead were performed. 1) In the lead workers compared with the controls, SDS-PAGE of protein in the erythrocyte membrane showed that relative concentrations of bands 1, 2, 3 and 4.1 were significantly decreased while those of bands 2.3, 6 and 7 were significantly increased. 2) SDS-PAGE of protein in the in vitro experiment showed that the relative concentrations of bands 1, 2, 3, 4.1 and 4.2 were decreased while those of bands 2.3, 4.5, 5, 6 and 7 were increased. Therefore, these results show the same trends as those of the in vivo experiments. 3) For the lead workers, the correlation coefficients between blood lead and bands 2, 2.3 and 3 were r = -0.414 (p less than 0.05), r = 0.545 (p less than 0.01) and r = -0.509 (p less than 0.01), respectively. Also a higher coefficient of correlation (r = -0.777, p less than 0.001) was found between bands 2 and 2.3. 4) As the molecular weight of substances showing bands 2 and 2.3 were 220700 and 133800, respectively, according to PAGE using molecular weight markers, band 2.3 is considered to be due to a cleavage product from that of band 2. From these results, we summarized as follows. Lead combined with erythrocyte membrane decreases the band 3 penetrating lipid bilayer, and that causes the decrease of membrane transportation. On the other hand, the variation of band 2 and 4.1 influences the spectrin-actin network. This is considered to be one of the reasons that MCV is decreased.