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Mn2+ prevents the Ca2+-induced inhibition of ATP synthesis in brain mitochondria
Abstract:
Uptake of Ca2+ by rat brain mitochondria causes an inhibition of respiratory stimulation by ADP, and the inhibition is relieved upon Na+-induced release of Ca2+ from the mitochondria, in accordance with earlier reports. We show that simultaneous uptake of Ca2+ and Mn2+ results in no inhibition of ADP-stimulated respiration, indicating that Mn2+ prevents the Ca2+-induced inhibition of ATP synthesis, without preventing Ca2+ accumulation in the mitochondria. The results are discussed in relation to a possible involvement of the mitochondrial ATPase-inhibitor protein in the observed effects of Ca2+ and Mn2+.
Insights
Manganese (Mn2+) prevents calcium (Ca2+)-induced inhibition of ATP synthesis in rat brain mitochondria without blocking Ca2+ uptake. This suggests Mn2+ protects mitochondrial respiration from Ca2+ overload effects.
Area of Science:
- Mitochondrial physiology
- Biochemistry
- Cellular respiration
Background:
- Calcium (Ca2+) uptake by mitochondria inhibits ADP-stimulated respiration.
- Sodium (Na+)-induced Ca2+ release reverses this inhibition.
Purpose of the Study:
- To investigate the effect of simultaneous manganese (Mn2+) and Ca2+ uptake on mitochondrial respiration.
- To determine if Mn2+ can prevent Ca2+-induced inhibition of ATP synthesis.
Main Methods:
- Studying Ca2+ and Mn2+ uptake in isolated rat brain mitochondria.
- Measuring ADP-stimulated respiration rates.
- Assessing ATP synthesis inhibition.
Main Results:
- Simultaneous uptake of Ca2+ and Mn2+ did not inhibit ADP-stimulated respiration.
- Mn2+ prevented Ca2+-induced inhibition of ATP synthesis.
- Mn2+ did not prevent Ca2+ accumulation in mitochondria.
Conclusions:
- Mn2+ protects mitochondrial function from Ca2+ overload.
- The mitochondrial ATPase-inhibitor protein may be involved in the protective mechanism of Mn2+.