Research On The NF-κB Mechanism Of Sevoflurane Preconditioning On Myocardium Against Ischemia-Reperfusion Injury In Rats

Objective1. Research on the protection of sevoflurane preconditioning on myocardium against ischemia-reperfusion injury in rats.2. Give Nuclear Factor-κB (NF-κB) inhibitor Parthenolide(PTN)in different times and research on the effect of NF-кB during the sevoflurane preconditioning.3. Measure NF-κB by Western Blot analysis before myocardial ischemia and after myocardial ischemia reperfusion, and research on the effect of NF-κB in the mechanism of sevoflurane preconditioning on myocardium against ischemia-reperfusion injury.MethodsExperiment 1st:Forty-eight male SD rats were randomly divided into six groups of 8 animals each and set up the model of myocardial ischemic-reperfusion in vivo: (A) Simple-Ischemic group;Rats were experienced myocardium ischemia-reperfusion merely. (B) PTN group;NF-κB inhibitor PTN (500μg/kg) was administered intraperitoneally(IP). (C) DMSO group;Dissolvent DMSO (Dimethylsulfoxide) was administered IP. (D) Sevoflurane group;Rats received 1MAC sevoflurane for 30 min and 15 min wash-out followed by a 30 min occlusion. (E) PTN+Sevoflurane group;PTN was administered IP 15 min before exposure to sevoflurane. (F) Sevoflurane+PTN group;PTN was administered IP after sevoflurane preconditioning. Tissue was obtained after 2 hour reperfusion. Myocardial infarct size was determined using triphenyltetrazolium chloride staining.Experiment 2nd: Part one: Forty-two male SD rats were randomly divided into seven groups of 6 animals each: (A) Control group (B) Simple-Ischemic group (C) Sevoflurane group (D) Sevoflurane 165min group (E) PTN group (F) PTN + Sevoflurane group (G) Sevoflurane+PTN group. In addition, Control group hadn't any treatment and rats of Sevoflurane 165min group received 1MAC sevoflurane for 30 min and then collected myocardium sample after 165min. Other groups were treated as the same as those of Experiment 1st. Myocardium sample of all groups were collected before the time of myocardial ischemia. NF-κB was determined by Western Blot analysis.Part two: Forty-two SD rats were randomly divided into seven groups of 6 animals each: (A) Control group (B) Simple-Ischemic group (C) Sevoflurane group (D) Sevoflurane 165min group (E) PTN group (F) PTN + Sevoflurane group (G) Sevoflurane+PTN group. In addition, myocardium sample of all groups were collected after myocardial ischemia reperfusion. NF-κB was determined by Western Blot analysis.ResultsExperiment 1st:During sevoflurane administered for 30 minutes, there was statistically significant difference in HR, MAP and RPP among Sevoflurane group, PTN+Sevoflurane group and Sevoflurane+PTN group (P<0.05) and during reperfusion 1 h and 2 h, there was statistically significant difference in MAP and RPP among all groups (P<0.05). Sevoflurane group significantly (P<0.05) reduced infarct size from (52.48±6.04)% [control (mean±SD)] to (33.73±5.72)% (P<0.05). Compared to Sevoflurane group (33.73±5.72)% , PTN+Sevoflurane group (52.60±5.01)% and Sevoflurane+PTN group (52.39±7.00)% had statistical difference (P<0.05).Experiment 2nd:Part one: Myocardium sample of all groups were collected before the time of myocardial ischemia: the expression of NF-κB protein was significantly up-regulated in Sevoflurane group as compared to that of the Control group,(P<0.05).Part two: Myocardium sample of all groups were collected after myocardial ischemia reperfusion: The expression of NF-κB protein was significantly up-regulated in Simple-Ischemic group than that in the Control group(,P<0.05) and the expression of NF-κB protein was significantly down-regulated in Sevoflurane group as compared to that of Simple-Ischemic group(P<0.05).Part three: The expression of NF-κB protein was significantly up-regulated in Simple-Ischemic group (myocardium sample were collected after myocardial ischemia reperfusion) than that in Simple-Ischemic group(myocardium sample of all groups were collected before the time of myocardial ischemia)(P<0.05). The expression of NF-κB protein was down-regulated significantly in Sevoflurane group(myocardium sample were collected after myocardial ischemia reperfusion ) as compared to that of Sevoflurane group (myocardium sample of all groups were collected before the time of myocardial ischemia)(P<0.05).ConclusionExperiment 1st:Preconditioning with sevoflurane reduces myocardial infarct size in rats, but PTN inhibits the protective effect of sevoflurane preconditioning, NF-κB may participate to protective mechanism of sevoflurane preconditioning.Experiment 2nd:NF-κB participates to protective mechanism of sevoflurane preconditioning. During sevoflurane preconditioning,NF-κB was activated obviously and thereby inhibited the activation of NF-κB after myocardial ischemia reperfusion, and then relieved myocardial ischemia-reperfusion injury. This may be the important mechanism of sevoflurane preconditioning on myocardium against ischemia-reperfusion injury in vivo.