Human erythrocyte membrane Ca2+ -ATPase during occupational exposure to lead

Abstract

Objective: Erythrocyte membrane Ca2+ - ATPase activity was determined in workers occupationally exposed to lead because of the prevalence of elevated blood lead in auto-mobile workers in some urban areas in Nigeria. Materials and methods: Blood lead levels, biochemical profiles, lipid peroxidation, basal and calmodulin stimulated Ca24 -ATPase activities were determined in erythrocytes of different categories of workers occupationally exposed to lead. These subjects were mainly battery chargers (BC), spray painters (SP) and auto mechanics (MC). Results: Estimation of erythrocyte Ca2+ -ATPase activity in the absence of calmodulin (basal activity) in test groups indicated that there were significant Specifically, blood lead levels were of the order: BC (5.5 folds) > SP (4 folds) > MC, although there was no significant difference between the blood lead levels in MC (10.60±2.55/xgPb2 7dl) and CT (8.51 ±4.55/xgPb7Vdl). Similarly, the order of reduction in Ca 2 *-ATPase activity was BC (69.8%)>SP (52.8%)>MC (32.6%). There was significant difference in the values obtained for MC and CT, ATPase activity being lower in MC compared to CT or healthy individuals. In the presence of calmodulin, basal ATPase activity was increased by at least four fold in erythrocytes from healthy subjects (CT) while the basal activity of the enzymes in membranes of BC, SP and MC was enhanced by about one and half times the activity of the pump in membranes from CT.