Alteration of erythrocyte membrane fluidity by heavy metal cations

Fluorescence polarization measurements were carried out on erythrocyte ghosts treated with heavy metal cations. Membranes labelled with the fluorescent lipid probe all-trans 1,6-diphenyl-1,3, 5-hexatriene (DPH) had increased DPH polarization (P) values, consistent with increased membrane lipid viscosity, when treated with 10(-3)-10(-2) M of the chloride salts of cadmium, zinc or lead for 1 hour at 37 degrees C, but not with calcium. Using cadmium as a prototype heavy metal, additional studies showed that exposure of ghosts to cadmium also increased the native protein fluorescence polarization. These increases in P values were observed at temperatures ranging from 15-40 degrees C. These data suggest that interaction of cadmium and other heavy metals with cellular membranes may alter membrane lipid and possibly membrane protein fluidity, which may contribute to abnormal cellular function.