SPECTROFLUOROMETRIC STUDIES ON ORGANOPHOSPHATE COMPOUNDS INFLUENCE OVER MEMBRANE POTENTIAL OF HUMAN LYMPHOCYTES AND K562 LYMPHOBLASTIC CELLS
Membrane potential controls several functions of both excitable and non-excitable cells. Evidence exists that, in the case of immune cells, membrane potential regulates receptor-mediated intracellular signaling. We investigated the effects of organophosphates pesticides chlorpyrifos, diazinon and malathion (1 - 1000 ng/mL), on the membrane potential of human lymphocytes and K562 lymphoblastic cells. To evaluate membrane potential changes, several slow-response fluorescent dyes were used comparatively. The experimental procedure has been set up by verifying microscopically the cell loading with dyes. The optimal concentrations of the dyes and the time required for cells loading have been set. The obtained results indicate the depolarizing effect exerted by organophosphates, mainly at high doses of organophosphate compounds, but, in some cases, lower concentrations seem to be active. Low-proliferating tumor cells are more sensitive to the depolarizing effect of organophosphates. Membrane potential alteration induced by organophosphates could result in negative consequences related to apoptosis, ion homeostasis, altered activation and proliferation capacity.
Keywords: membrane potential, organophosphates pesticides, human lymphocytes, K562 cells