Reduction of Mercuric Ion and Exhalation of Mercury in Acatalasemic and Normal Mice

Abstract

A significant difference in the amount of exhaled mercury per hour between normal and acatalasemic mice was observed in 7 of 11 experiments for different periods of time. The total amount of mercury exhaled from acatalasemic mice was significantly higher than those of normal mice. The results confirm that the reduction of mercuric ion to metallic mercury occurs by recycling of mercury in the tissues and reoxidized metallic mercury to mercuric ion by catalase. Mercuric ion was reduced to metallic mercury in the presence of superoxide anion in vitro. The reduction rate of mercuric ion to metallic mercury in the presence of both superoxide anion and cytochrome C or nitro blue tetrazolium was higher than that in the presence of superoxide anion alone, and the reduction of mercuric ion by NADPH or NADH was also observed. The reduction of mercuric ion to metallic mercury by liver homogenates of acatalasemic mice was higher than that of normal mice.

First record on mercury accumulation in mice brain living in active volcanic environments: a cytochemical approach

“…Since the mercuric form is not able to pass through the plasma membrane and leave the cell, it is reduced again to Hg 0 , which can travel from cell to cell. These reductions mechanisms are not well described, although experiments in vitro suggest that the anion superoxide and coenzymes, such as NADH and NADPH, can carry out this process (Ogata et al 1987).…”

Mechanisms of mercury disposition in the body

“…The mechanisms of reduction are not well described but several processes may be involved. In vitro, the superoxide anion can perform this task as well as NADPH and NADH [Ogata et al, 1987]. The exhalation rate is increased by treatment of the animals with ethanol [Dunn et al, 1981a,b].…”

Superoxide-Mediated Extracellular Mercury Reduction by Aerobic Marine Bacterium Alteromonas sp. KD01

“…Theoretical calculations for Hg species in seawater (Table S2) suggest that even if considering the complexation of Hg­(II) with organic matter, Cl – , and OH – in seawater, the concentration of free Hg 2+ (3.29 × 10 –22 M) in seawater is still significantly higher than 5.86 × 10 –23 M. Therefore, based on the thermodynamic calculation, superoxide-mediated Hg­(II) reduction was thermodynamically possible in seawater. Reports have suggested that superoxide acts as a reductant for Hg­(II) in xanthine-xanthine oxidase and photoirradiated dissolved black carbon …”

“…When C Hg 2+ > 5.86 × 10 −23 M, E > 0, ΔG < 0. Theoretical calculations for Hg species in seawater (Table S2) suggest that even if considering the complexation of Hg(II) with organic matter, Cl − , and OH − in seawater, the concentration of free 59 and photoirradiated dissolved black carbon. 60 Whether superoxide-mediated Hg(II) reduction is thermodynamically possible depends on the concentration of free Hg(II) in seawater.…”