Influence of environmental lead on membrane ion transport in a French urban male population.

Red cell cation transports (Na(+)-K+ pump, Na(+)-K+ cotransport system, Na(+)-Li+ countertransport, and Na+ and K+ passive permeabilities) and blood and hair lead levels were measured in 129 healthy adult Caucasians not occupationally exposed to lead. In agreement with previously reported in vitro results showing a lead-induced Na(+)-K+ ATPase inhibition, Na(+)-K+ pump activity was inversely correlated with hair lead (r = -0.18, P less than 0.05); it was not significantly correlated with blood lead. Na(+)-K+ cotransport activity was inversely correlated with blood lead contents (r = -0.23, P less than 0.05) but not with hair lead. No significant correlation was found between the remaining cation transport pathways and lead levels. It is hypothesized that environmental, long-term exposure to lead may result in pump inhibition, while a recent exposition to lead may result in inhibition of the Na(+)-K+ cotransport system. Further research is required in order to determine if red cell Na(+)-K+ pump and Na(+)-K+ cotransport activities are sensitive indicators of chronic and recent exposures to lead, respectively.