Fluorescent imaging of acute mercuric chloride exposure on cultured human kidney tubular epithelial cells

Background. Imaging of intracellular mercuric ion is necessary for mechanism of renal toxicity of exposure to HgCl₂. The distribution of Hg²⁺ inside a living cell, however, is still invisible due to the lack of high selective and sensitive fluorescent molecular probe for Hg ²⁺. Methods. A new fluorescent probe, EPNP, was applied to the cultured cells of human kidney proximal tubular epithelial cell line (HKC) in the presence of HgCl₂ and some other bivalent ions. The relative fluorescence intensity of EPNP was measured and fluorescence images were taken by laser scanning confocal microscope. Results. Results showed it led to an Hg²⁺ concentrationand time-dependent increase in fluorescence intensity, and responded weakly for some other heavy and transition metal ions. It could be seen during acute exposure on HKC cells, Hg²⁺ locate perinuclear, and on nuclear membrane, which was beyond what one knew before. Conclusion. EPNP is a real-time and on-line probe for imaging Hg²⁺ in a living cell due to its high selectivity and sensitivity for Hg²⁺ and slow bleaching/fading. Both the probe and the new results about the distribution of intracellular Hg²⁺ may be helpful for relevant biologic research.