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The interactions between nitric oxide and brain nerve terminals as studied by electron paramagnetic resonance
1Department of Paediatrics, University College London Medical School, Rayne Institute, UK.
Biochemical and Biophysical Research Communications
|July 17, 1995
Summary
Nitric oxide (NO) toxicity in brain cells does not stem from damage to mitochondrial iron-sulfur centers. Instead, research indicates cytochrome oxidase is the primary target for NO
Area of Science:
- Biochemistry
- Neuroscience
- Toxicology
Background:
- Mitochondrial iron-sulfur (Fe-S) centers are proposed targets for nitric oxide (NO) toxicity.
- NO-induced damage to Fe-S centers may inhibit mitochondrial respiration and form EPR-detectable complexes (g = 2.04).
Purpose of the Study:
- To investigate the role of Fe-S centers in NO-induced mitochondrial dysfunction.
- To determine if EPR-detectable Fe-S dinitrosyl complexes correlate with respiration inhibition.
Main Methods:
- Rat brain synaptosomes were treated with nitroprusside, an NO and NO+ donor.
- Electron Paramagnetic Resonance (EPR) spectroscopy was used to detect Fe-S dinitrosyl complexes.
- Mitochondrial respiration rates were measured.
Main Results:
- Large concentrations of EPR-detectable Fe-S dinitrosyl complexes were generated.
- No correlation was observed between the EPR signal intensity and the degree of respiration inhibition.
- Mitochondrial Fe-S protein EPR signals showed no significant loss.
Conclusions:
- The formation of EPR-detectable Fe-S dinitrosyl complexes does not directly correlate with NO-induced inhibition of synaptosomal respiration.
- Cytochrome oxidase, not mitochondrial Fe-S enzymes, is the primary target for NO inhibition of brain cell respiration.