Abstract: Human dopaminergic SH-SY5Y cells were exposed to manganese of bivalence and trivalence at the concentrations of 0.25, 0.50, 0.75 mmol/L for 24 h respectively. The mitochondrial potential was determined by incubating the culture with Rhodamine 123, a mitochondrial specific dye, followed by laser scanning confocal microtechnique(LCSM)analyses of fluorescence signal. Results showed that Mn(Ⅱ)and Mn(Ⅲ)treatment significantly decreased fluorescence signal as compared to the controls, suggesting a diminished mitochondrial membrane potential after Mn treatment. The effects were Mn-concentration dependent. In addition, we found that Mn(Ⅲ)appeared to be more cytotoxic than Mn(Ⅱ)in altering mitochondrial membrane potential at the concentration of 0.50 mmol/L and 0.75 mmol/L. These data confirm that mitochondria may serve as the primary target for Mn cytotoxicity by altering the membrane potential.

Key words: manganese, laser scanning confocal microtechnique(LCSM), mitochondria, membrane potential