Na+/H+ exchanger inhibitor, FR183998, has protective effect in lethal acute liver failure and prevents iNOS induction in rats

Background/Aims Selective inhibition of Na+/H+ exchanger (NHE) improves organ dysfunctions including heart ischemia–reperfusion injury. In vivo and in vitro studies were designed to investigate whether NHE inhibitor has a protective effect in lethal acute liver failure, and if so, what are the mechanisms involved. Methods NHE inhibitor (FR183998) was administered to rats treated with d-galactosamine/lipopolysaccharide (GalN/LPS), or incubated with cultured hepatocytes stimulated by pro-inflammatory cytokine, interleukin (IL)-1β. Results FR183998 reduced the increases of pro-inflammatory cytokines such as TNF-α, interferon-γ and CINC-1, but enhanced the anti-inflammatory cytokine, IL-10, leading to the prevention of liver injury and increased survival rate in GalN/LPS-treated animals. FR183998 prevented the activation of transcription factor NF-κB induced by GalN/LPS. In vivo and in vitro experiments revealed that FR183998 reduced inducible nitric oxide synthase (iNOS) induction and NO production. Further FR183998 decreased levels of iNOS antisense-transcript in GalN/LPS-treated liver and IL-1β-treated hepatocytes. Conclusions FR183998 may reduce a variety of inflammatory mediators such as cytokines and NO in part through the inhibition of NF-κB activation, resulting in the prevention of fulminant liver failure, and may inhibit iNOS gene expression at steps of iNOS promoter transactivation and its mRNA stabilization through NF-κB and iNOS antisense-transcript, respectively.