Effect of micromolar concentrations of manganese ions on calcium-ion cycling in rat liver mitochondria.
The effects of micromolar concentrations of Mn2+ on the rat liver mitochondrial Ca2+ cycle were investigated. It was found that the addition of Mn2+ to mitochondria which were cycling 45Ca2+ led to a rapid dose dependent decrease in the concentration of extramitochondrial 45Ca2+ of about 1 nmol/mg of protein. The effect was complete within 30 s, was half maximal with 10 microM Mn2+ and was observed in the presence of 3 mM Mg2+ and 1 mM ATP. It occurred over a broad range of incubation temperatures, pH and mitochondrial Ca2+ loads. It was not observed when either Mg2+ or phosphate was absent from the incubation medium, or in the presence of Ruthenium Red. These findings indicate that micromolar concentrations of Mn2+ stimulate the uptake of Ca2+ by rat liver mitochondria, and provide evidence for an interaction between Mg2+ and Mn2+ in the control of mitochondrial Ca2+ cycling.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010710:Phosphates / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012430:Ruthenium Red / Q000494:pharmacology; D013324:Strontium / Q000494:pharmacology; D013696:Temperature
D002413:Cations, Divalent; D010710:Phosphates; D012430:Ruthenium Red; D008345:Manganese; D008274:Magnesium; D002118:Calcium; D013324:Strontium