Changes of membrane fluidity in erythrocytes of lead-exposed workers

Abstract

We have studied the effect of lead on the fluidity of erythrocyte membrane to clarify if lead can interact in vivo with biological membranes. Erythrocyte membranes were chosen in our study because a decrease of red cell osmotic fragility is also evident in the absence of laboratory and clinical signs of anaemia. The study was undertaken using the Electron Spin Resonance technique with two spin labels 5-doxyl stearate and 16-doxyl-stearate, which probe the physical state of the polar surface and the inner core of the membrane respectively. Red blood cells and erythrocyte ghosts were prepared from the blood of workers occupationally exposed to lead and from healthy controls. The determinations of Pb blood, Pb urine, urine coproporphyrin and delta-aminolevulinic acid showed an increased internal dose of lead, but the ordinary metabolic and haematological parameters were in the normal range. Our results show that in lead workers there is a change in chemical physical state both in erythrocytes and erythrocyte ghosts consistent with a decrease of membrane fluidity, which is evident in the surface as well as in the inner core of the membrane. The degree of membrane fluidity modification does not appear correlated with blood lead level. Changes in the membrane structural organization could be the molecular basis of some pathological alterations induced by lead.

Evaluation of peripheral blood neutrophil leucocytes in lead-exposed workers

“…Lead acts directly by inhibiting neutrophil chemotactic activity both in vivo and in vitro (Governa et al 1987(Governa et al , 1988. Furthermore, it can interfere with their cell membrane fluidity in vivo (Valentino et al 1982) and with their cytoplasmic microtubular network in vitro (Bonacker et al 2005).…”

Effect of lead on the levels of some immunoregulatory cytokines in occupationally exposed workers

“…In previous experiments in vitro , we have shown that Pb modifies membrane fluidity of erythrocytes of Pb-exposed workers, as well as membrane fluidity of neutrophils. 2,31 Moreover, TNF-a is able to increase the production of IL10. In our Pb-exposed workers, the increased concentration of IL-10 might be secondary to the increased production of TNF-a.…”

Combined efficacies of lipoic acid and meso-2,3-dimercaptosuccinic acid on lead-induced erythrocyte membrane lipid peroxidation and antioxidant status in rats

“…7 Several studies have focussed on the possible toxic effects of lead on membrane components and have identified a correlation between these effects and lead-induced oxidative damage. 8 *Correspondence: P Varalakshmi, Department of Medical Biochemistry, Dr AL Mudaliar Post Graduate Institute of Basic Medical Sciences, University of Madras (Taramani), Chennai-600 113, India E-mail: drvlakshmi@yahoo.com It is known that lead exerts its influence on the erythrocyte membrane, bringing about changes in the osmotic and mechanical fragility of erythrocytes, 9 enhancement of potassium loss from the cells, 10 reduction of the membrane Na 1 , K 1 -ATPase activity, 11 decreases in the membrane fluidity 12 and changes in the composition of erythrocyte membrane proteins. 13 Lead is also known to inhibit calcium efflux mediated by Ca(Mg)-ATPase.…”