Nitrosative protein oxidation is modulated during early endotoxemia

Area of Science:

• Biochemistry
• Cardiovascular Physiology
• Molecular Biology

Background:

• Endotoxemia-induced cardiovascular dysfunction is linked to nitric oxide and reactive nitrogen species.
• Nitrosative stress can alter protein function through post-translational modifications.

Purpose of the Study:

• To investigate changes in protein S-nitrosylation and tyrosine nitration during endotoxemia.
• To identify specific protein targets affected by these modifications.

Main Methods:

• Utilized the ascorbate-dependent biotin-switch method to assay protein S-nitrosylation.
• Employed mass spectrometry to identify S-nitrosylated proteins.
• Immunoblotting was used to detect tyrosine nitration.
• Assessed the effect of peroxynitrite scavenger FeTPPS on hypotension.

Main Results:

• No significant change in global protein S-nitrosylation initially, but a time-dependent loss was observed.
• Identified specific S-nitrosylated proteins and confirmed their decreased nitrosylation in endotoxemic hearts.
• Observed a time-dependent increase in tyrosine nitration correlating with decreased mean arterial pressure.
• FeTPPS failed to reduce protein nitration and worsened hypotension.

Conclusions:

• Sepsis leads to a dynamic shift in protein nitrosative modifications, with decreased S-nitrosylation and increased tyrosine nitration.
• Increased tyrosine nitration, potentially mediated by peroxynitrite, contributes to endotoxemia-induced hypotension.
• The peroxynitrite scavenger FeTPPS was ineffective and exacerbated hypotension.