Brain, kidney and liver 203Hg-methyl mercury uptake in the rat: relationship to the neutral amino acid carrier

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Abstract

To investigate the effect of L-neutral amino acids on tissue levels of methyl mercury in the adult animal, rats were infused into the external jugular vein with solutions containing a) 0.05 mM 203Hg-MeHgCl and saline, b) 0.05 mM 203Hg-MgHgCl-0.1 mM L-cysteine, c) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-methionine, d) 0.05 mM 203Hg-MeHgCl-0.1 mM L-leucine, or e) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-leucine. Groups of animals were sacrificed at 3 min, 7 hr, and 96 hr. Brain, kidney and liver 203Hg radioactivity was measured by means of gamma-scintillation spectrometry. Brain 203Hg concentrations L-cysteine treated animals were significantly higher compared with saline treated animals (P <0.05) at 3 min, 7 hr and 96 hr. The coinjection or coinfusion of methyl mercury with L-cysteine and L-methionine abolished the L-cysteine mediated brain 203Hg uptake (P <0.05), at each sacrifice time. Kidney and liver 203Hg concentrations were not significantly different in any of the treatment groups compared with controls, irrespective of the sacrifice time. Furthermore, the percentage of diffusible 203Hg (non-protein-bound) at each sacrifice time was not statistically different irrespective of the treatment assigned. These results suggest that methyl mercury L-cysteine conjugates in the plasma may share a common transport step with the L-neutral amino acid carrier transport system and indicate the presence in brain capillaries of a transport system capable of selectively mediating methyl mercury uptake across the capillary endothelial cell membrane.

Original languageEnglish (US)
Pages (from-to)17-20
Number of pages4
JournalPharmacology and Toxicology
Volume65
Issue number1
StatePublished - 1989
Externally publishedYes

Fingerprint

Neutral Amino Acids
Mercury
Liver
Cysteine
Rats
Brain
Kidney
Animals
Leucine
Methionine
Neutral Amino Acid Transport Systems
Gamma Spectrometry
Carrier transport
Jugular Veins
Endothelial cells
Radioactivity
Scintillation
Cell membranes
Spectrometry
Endothelial Cells

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Pharmacology
  • Toxicology

Cite this

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title = "Brain, kidney and liver 203Hg-methyl mercury uptake in the rat: relationship to the neutral amino acid carrier",
abstract = "To investigate the effect of L-neutral amino acids on tissue levels of methyl mercury in the adult animal, rats were infused into the external jugular vein with solutions containing a) 0.05 mM 203Hg-MeHgCl and saline, b) 0.05 mM 203Hg-MgHgCl-0.1 mM L-cysteine, c) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-methionine, d) 0.05 mM 203Hg-MeHgCl-0.1 mM L-leucine, or e) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-leucine. Groups of animals were sacrificed at 3 min, 7 hr, and 96 hr. Brain, kidney and liver 203Hg radioactivity was measured by means of gamma-scintillation spectrometry. Brain 203Hg concentrations L-cysteine treated animals were significantly higher compared with saline treated animals (P <0.05) at 3 min, 7 hr and 96 hr. The coinjection or coinfusion of methyl mercury with L-cysteine and L-methionine abolished the L-cysteine mediated brain 203Hg uptake (P <0.05), at each sacrifice time. Kidney and liver 203Hg concentrations were not significantly different in any of the treatment groups compared with controls, irrespective of the sacrifice time. Furthermore, the percentage of diffusible 203Hg (non-protein-bound) at each sacrifice time was not statistically different irrespective of the treatment assigned. These results suggest that methyl mercury L-cysteine conjugates in the plasma may share a common transport step with the L-neutral amino acid carrier transport system and indicate the presence in brain capillaries of a transport system capable of selectively mediating methyl mercury uptake across the capillary endothelial cell membrane.",
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T1 - Brain, kidney and liver 203Hg-methyl mercury uptake in the rat

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AU - Aschner, Michael

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AB - To investigate the effect of L-neutral amino acids on tissue levels of methyl mercury in the adult animal, rats were infused into the external jugular vein with solutions containing a) 0.05 mM 203Hg-MeHgCl and saline, b) 0.05 mM 203Hg-MgHgCl-0.1 mM L-cysteine, c) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-methionine, d) 0.05 mM 203Hg-MeHgCl-0.1 mM L-leucine, or e) 0.05 mM 203Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-leucine. Groups of animals were sacrificed at 3 min, 7 hr, and 96 hr. Brain, kidney and liver 203Hg radioactivity was measured by means of gamma-scintillation spectrometry. Brain 203Hg concentrations L-cysteine treated animals were significantly higher compared with saline treated animals (P <0.05) at 3 min, 7 hr and 96 hr. The coinjection or coinfusion of methyl mercury with L-cysteine and L-methionine abolished the L-cysteine mediated brain 203Hg uptake (P <0.05), at each sacrifice time. Kidney and liver 203Hg concentrations were not significantly different in any of the treatment groups compared with controls, irrespective of the sacrifice time. Furthermore, the percentage of diffusible 203Hg (non-protein-bound) at each sacrifice time was not statistically different irrespective of the treatment assigned. These results suggest that methyl mercury L-cysteine conjugates in the plasma may share a common transport step with the L-neutral amino acid carrier transport system and indicate the presence in brain capillaries of a transport system capable of selectively mediating methyl mercury uptake across the capillary endothelial cell membrane.

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