Related Experiment Videos
Tetrahydrobiopterin-dependent nitrite oxidation to nitrate in isolated rat hepatocytes
1Department of Surgery, University of Pittsburgh School of Medicine, PA 15261.
FEBS Letters
|October 18, 1993
Summary
Rat liver cells convert nitrite to nitrate, a reaction crucial for understanding nitric oxide metabolism. This finding suggests current nitric oxide assays may be inaccurate.
Area of Science:
- Biochemistry
- Cell Biology
- Nitric Oxide Metabolism
Background:
- Nitric oxide (NO) is a critical signaling molecule.
- NO can be oxidized to nitrite (NO2-).
- The fate of NO2- in mammalian systems is not fully understood.
Purpose of the Study:
- To investigate the metabolic fate of nitrite in mammalian cells.
- To characterize the enzymatic conversion of nitrite to nitrate.
- To assess the implications for nitric oxide measurement.
Main Methods:
- Incubation of isolated rat hepatocytes with sodium nitrite.
- Analysis of cell extracts for nitrite-to-nitrate conversion activity.
- Enzyme inhibition studies using cyanide and carbon monoxide.
- Heat denaturation assays.
Main Results:
- Hepatocytes and cell extracts stoichiometrically convert nitrite to nitrate.
- This conversion requires tetrahydrobiopterin in cell extracts.
- The reaction is inhibited by cyanide but not carbon monoxide.
- The mechanism is heat-sensitive and not peroxidative or radical-based.
Conclusions:
- A novel mammalian pathway for inorganic nitrogen oxide oxidation exists.
- This pathway may protect against endogenous NO-derived damage.
- Nitrite determination alone may be unreliable for NO production assays.