Triclosan, an environmental pollutant from health care products, evokes charybdotoxin-sensitive hyperpolarization in rat thymocytes

Abstract

The effects of triclosan, an environmental pollutant from household items and health care products, on membrane potential and intracellular Ca 2+ concentrations of rat thymocytes were examined by a flow cytometry with fluorescent probes, di-BA-C 4 and fluo-3-AM, because triclosan is often found in humans and wild animals. Triclosan at a concentration of 3 μM decreased the intensity of di-BA-C 4 fluorescence, indicating the triclosan-induced hyperpolarization. The application of charybdotoxin, a specific inhibitor of Ca 2+-dependent K + channels, and the removal of external Ca 2+ eliminated the triclosan-attenuation of di-BA-C 4 fluorescence. Furthermore, triclosan augmented the fluo-3 fluorescence under normal Ca 2+ condition, indicating that triclosan increased intracellular Ca 2+ concentration. These results suggest that triclosan induces membrane hyperpolarization by increasing intracellular Ca 2+ concentration that activates Ca 2+-dependent K + channels. Since the change in membrane potential of lymphocytes influence cellular immune functions, triclosan may exert adverse actions on immune system in human and wild animals.