Imah-Harry J U, Akiibinu M O, Omotosho I O, Olorunsogo O O
Laboratories for Biomembrane Research and Biotechnology, Department of Biochemistry, College of Medicine, University of Ibadan, Ibadan, Nigeria.
Afr J Med Med Sci. 2012 Dec;41 Suppl:91-7.
Erythrocyte membrane Ca(2+)-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.
Blood lead levels, biochemical profiles, lipid peroxidation, basal and calmodulin-stimulated Ca(2+)-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).
Estimation of erythrocyte Ca(2+)-ATPase activity in the absence of calmodulin (basal activity) in test groups indicated that there were significant reductions in the pump function and this correlated very well with the levels of lead in their blood. 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 microgPb2+/dl) and CT (8.51 +/- 4.55 microgPb2+/dl). 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. The levels of total serum protein and albumin increased significantly in BC, SP and MC when compared to healthy subjects (CT). C-reactive proteins (C-RP) levels were higher in BC, SP and MC in comparison to CT. The levels of MDA were high in all lead-exposed workers, BC > SP > MC relative to CT. Although, there were significant decreases in the PCV values of all the groups occupationally exposed to lead compared to values obtained for CT, cholesterol level increased significantly only in BC when compared to the other groups.
These observations are probably due to the integrity of the plasma membrane of these workers and the ability of the heavy metal to compete with Ca2+ in the catalytic cycle and Ca2+ transport mechanism of the pump protein.
由于尼日利亚一些城市地区汽车工人血铅水平普遍升高，因此对职业性接触铅的工人的红细胞膜钙（Ca2+）-ATP酶活性进行了测定。
对不同类别的职业性接触铅的工人的红细胞，测定血铅水平、生化指标、脂质过氧化、基础及钙调蛋白刺激的钙（Ca2+）-ATP酶活性。这些受试者主要是电池充电器工人（BC）、喷漆工（SP）和汽车修理工（MC）。
测试组中在无钙调蛋白情况下（基础活性）对红细胞钙（Ca2+）-ATP酶活性的评估表明，泵功能有显著降低，且这与他们血液中的铅水平密切相关。具体而言，血铅水平顺序为：BC（5.5倍）>SP（4倍）>MC，尽管MC（10.60±2.55微克Pb2+/分升）和对照组（CT，8.51±4.55微克Pb2+/分升）的血铅水平之间无显著差异。同样，钙（Ca2+）-ATP酶活性降低顺序为：BC（69.8%）>SP（52.8%）>MC（32.6%）。MC和CT所测值存在显著差异，MC中的ATP酶活性低于CT或健康个体。在有钙调蛋白存在的情况下，健康受试者（CT）红细胞中的基础ATP酶活性至少增加了四倍，而BC、SP和MC细胞膜中酶的基础活性比CT细胞膜中泵的活性提高了约1.5倍。与健康受试者（CT）相比，BC、SP和MC中的总血清蛋白和白蛋白水平显著升高。BC、SP和MC中的C反应蛋白（C-RP）水平高于CT。所有铅接触工人中的丙二醛（MDA）水平都很高，相对于CT，BC>SP>MC。尽管与CT所测值相比，所有职业性接触铅的组的红细胞压积（PCV）值都有显著降低，但与其他组相比，仅BC中的胆固醇水平显著升高。
这些观察结果可能归因于这些工人质膜的完整性以及重金属在催化循环和泵蛋白的钙（Ca2+）转运机制中与Ca2+竞争的能力。
