Effects of Nitrite Addition to IGL-1 Solution on Rat Liver Preservation

BACKGROUND The ability of nitrite to provide protection following ischemia/reperfusion (I/R) has been demonstrated, but its mechanism is still poorly understood. This study aimed to determine the optimal nitrite concentration to add into Institut Georges Lopez (IGL-1) storage solution and to assess its effect on antioxidant enzymes and autophagy. MATERIAL AND METHODS Livers from Sprague-Dawley rats were conserved in IGL-1 for 24 hours at 4°C or in IGL-1 enriched with nitrite at 50, 500 and 1,000 nM, respectively, before being perfused ex-vivo at 37 °C for 120 minutes. Sham livers were perfused ex vivo without cold preservation. RESULTS All biological and functional parameters of the preserved livers were significantly impaired as compared to shams. Interestingly, the supplementation of nitrite to IGL-1 protected the liver from I/R injury. Among the doses of nitrite evaluated, the 50 nM was proved efficient: it significantly reduced cytolysis, mitochondrial damage, and lipid peroxidation, and enhanced antioxidant enzyme activity (superoxide dismutase, catalase, and glutathione peroxidase activity) and hepatic function parameters (portal resistance, bile flow, and bromosulfophthalein clearance). In addition, increased levels of the autophagy parameters were observed when 50 nM of nitrite were added to IGL-1 solution, but this effect disappeared completely with higher concentrations of nitrite. CONCLUSIONS It seems that 50 nM of nitrite added to IGL-1 is the optimal concentration able to maintain cell integrity and hepatic function through autophagy induction and oxidative stress prevention.