Lead ions but not other metallic ions increase resistance to hypotonic lysis in prenatal hemopoiesis red blood cells

Metals known to have toxic effects on exposed individuals (Aluminum (Al), Cadmium (Cd), Zinc (Zn) and lead (Pb)) were selected. Umbilical cord erythrocytes from normal newborns were incubated in isotonic media alone or with addition of Pb (20 microM), Cd, Zn or Al (concentration range: 20-250 microM). Red cells were then placed in media of diminishing tonicity, to measure cellular lysis and volume; the regression curves of percent lysis as a function of osmolarity were determined for each data set and the break points calculated. Resistance to lysis increased significantly in Pb treated cells whereas cells treated with the other metals did not differ from controls, even at concentrations ten times higher than that of Pb. Lead produced a reduction in cellular volume corrected by addition of quinidine (an inhibitor of potassium channels activation) to the cell suspension; on the other hand, quinidine did not modify the effect of lead on lysis sensitivity. These results suggest that the effect of lead on cell resistance to lysis might be mediated by changes in membrane structure. The other metals examined did not affect the variables studied.

Efecto de la bilirrubina no conjugada sobre los contenidos ionicos y la sensibilidad a hemolisis hiposmotica en eritrocitos. / Effect of unconjugated bilirubin on ionic contents and sensitivity to hyposmotic hemolysis in erythrocytes

Se estudio, in vitro, el efecto de la bilirrubina no conjugada sobre el contenido intracelular de sodio, potasio y cloruro, asi como la sensibilidad a hemolisis de eritrocitos humanos provenientes de adultos normales. Las modificaciones de los contenidos ionicos se relacionaron con la concentracion de bilirrubina libre en el medio de incubacion. El contenido de cloruro intracelular fue el mas sensible a la accion de la bilirrubina y la perdida desde las celulas se realizo contra su gradiente de concentracion. Se observo, ademas, un incremento significativo en la sensibilidad a la hemolisis hiposmotica, probablemente como consecuencia de la accion de la bilirrubina no conjugada (BNC) sobre la estructura de membrana. Se sugiere que la modificacion del contenido de cloruro en los eritrocitos podria ser un indice de la toxicidad celular de BNC y un criterio adicional a considerar en decisiones terapeuticas