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Manganese and calcium efflux kinetics in brain mitochondria. Relevance to manganese toxicity

C E Gavin1, K K Gunter, T E Gunter

  • 1University of Rochester Medical Center, NY 14642.

The Biochemical Journal
|March 1, 1990
PubMed

Insights

Manganese (Mn2+) accumulates in brain mitochondria and hinders calcium (Ca2+) removal. This study shows Mn2+ blocks Ca2+ efflux, suggesting potential co-accumulation during manganese intoxication.

Area of Science:

  • Neuroscience
  • Mitochondrial Biology
  • Toxicology

Background:

  • Manganese (Mn2+) influx into mitochondria shares a mechanism with calcium (Ca2+).
  • Manganese accumulates in brain mitochondria and is slowly cleared.
  • Understanding manganese and calcium efflux is crucial for neurotoxicity research.

Purpose of the Study:

  • To investigate the mitochondrial efflux kinetics of both Mn2+ and Ca2+ in the brain.
  • To determine the role of Na+ in Mn2+ and Ca2+ efflux.
  • To explore the competitive interactions between Mn2+ and Ca2+ in mitochondrial efflux.

Main Methods:

  • Utilized dual-label isotope techniques to track Mn2+ and Ca2+ efflux.
  • Examined Na+-dependent and Na+-independent efflux pathways.
  • Assessed the inhibitory effects of Mn2+ on Ca2+ efflux and vice versa.

Main Results:

  • No significant Na+-dependent Mn2+ efflux was observed from brain mitochondria.
  • Mn2+ competitively inhibited both Na+-dependent and Na+-independent Ca2+ efflux.
  • Ca2+ did not significantly inhibit Mn2+ efflux from brain mitochondria.

Conclusions:

  • Manganese (Mn2+) efflux from brain mitochondria is primarily Na+-independent.
  • Manganese significantly inhibits calcium (Ca2+) efflux, suggesting competitive interaction.
  • Findings indicate a potential for mitochondrial co-accumulation of Mn2+ and Ca2+ in manganese-intoxicated brain tissue.

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