Antibacterial peptide PR-39 affects local nitric oxide and preserves tissue oxygenation in the liver during septic shock

The effects of the antibacterial peptide PR-39 on nitric oxide (NO) and liver oxygenation (pO₂) in a mouse model of endotoxaemia have been explored. In vivo electron paramagnetic resonance (EPR) spectroscopy was used to make direct measurements of liver NO and pO₂. Measurements of pO₂ were made at two different anatomical locations within hepatic tissue to assess effects on blood supply (hence oxygen supply) and lobule oxygenation; selectively from the liver sinusoids or an average pO₂ across the liver lobule. PR-39 induced elevated levels of liver NO at 6 h following injection of lipopolysaccharide (LPS) as a result of increased iNOS expression in liver, but had no effect on eNOS or circulatory NO metabolites. Sinusoidal oxygenation was preserved, and pO₂ across the hepatic tissue bed improved with PR-39 treatment. We propose that the beneficial effects of PR-39 on liver in this septic model were mediated by increased levels of local NO and preservation of oxygen supply to the liver sinusoids.