title: Role of endothelial nitric oxide synthase in remote ischemic preconditioning of the mouse liver.
abstract: Hindlimb remote ischemic preconditioning (RIPC) reduces liver ischemia/reperfusion (IR) injury in wild-type mice. The underlying mechanisms of RIPC are currently unknown. In this study, we investigated the role of endothelial nitric oxide synthase (eNOS) in mediating the protective effects of RIPC. Endothelial nitric oxide synthase knockout (eNOS(-/-) ) mice were divided into 4 groups: (1) a sham surgery group, (2) an RIPC group (6 cycles of 4 minutes of hindlimb ischemia and 4 minutes of hindlimb reperfusion), (3) an IR group [40 minutes of lobar (70%) hepatic ischemia and 2 hours of reperfusion], and (4) an RIPC+IR group (RIPC followed by the IR group procedures). Plasma liver aminotransferases, hepatic histopathological injury scores, transmission electron microscopy studies, and hepatic microcirculatory blood flow (MBF) were assessed. eNOS protein expression was analyzed in the livers and hindlimb muscles of wild-type mice. Hindlimb RIPC did not protect against subsequent liver IR injury in eNOS(-/-) mice; this was demonstrated by the lack of reduction in the plasma aminotransferase levels, histopathological scores, or ultrastructural features of IR injury in the RIPC+IR group versus the IR group. Hepatic MBF did not recover during liver reperfusion in the RIPC+IR group versus the IR group. eNOS protein expression was similar among all wild-type groups. In conclusion, eNOS is essential for the protective effects of hindlimb RIPC on liver IR injury. eNOS exerts its protective effects through the preservation of hepatic MBF. At 2 hours of reperfusion, eNOS protection is likely due to the increased activation of eNOS rather than increased expression.
authors.affiliation: Liver Transplantation and Hepatobiliary Unit, Royal Free Hospital, London, UK.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Abu-Amara
authors.forename: Shi Yu
authors.initials: SY
authors.lastname: Yang
authors.forename: Alberto
authors.initials: A
authors.lastname: Quaglia
authors.forename: Peter
authors.initials: P
authors.lastname: Rowley
authors.forename: Barry
authors.initials: B
authors.lastname: Fuller
authors.forename: Alexander
authors.initials: A
authors.lastname: Seifalian
authors.forename: Brian
authors.initials: B
authors.lastname: Davidson
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D006614:Hindlimb / Q000503:physiopathology*; D007150:Immunohistochemistry / Q000379:methods; D019194:Ischemic Preconditioning / Q000379:methods*; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000502:physiology*; D015424:Reperfusion; D015427:Reperfusion Injury
chemical_list: D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III