远距预处理对心肌缺血再灌注损伤的影响

观察肢体缺血预处理对在体和离体心脏缺血再灌注 (I/R)的影响 ,探讨其发生的可能机制。分别制备在体、离体和远距预处理大鼠心肌梗死模型 ,将 6 0只大鼠随机分为 6组 ,①在体心脏I/R组 (IR1组 ) ,②预处理后在体心脏I/R组 (PC1组 ) ,③离体心脏I/R组 (IR2 组 ) ,④预处理后摘取离体心脏I/R组 (PC2 组 ) ,⑤两组空白对照组 (C1,C2 )各组 10只大鼠。结果 :⑥PC1组与IR1组比较 ,心肌梗死面积明显减少 (12 .9%± 1.7%vs 39.2 %± 2 .4 % ,P <0 .0 1) ,室性心律失常发生率降低 (8.3%vs4 1.7% ,P <0 .0 5 ) ,血CK含量降低 (86 3.35± 139.87vs12 5 0 .16± 36 9.33U/L ,P <0 .0 1) ,血清MDA含量减少 (2 .2 4± 0 .4 2vs 4 .5 3± 0 .30 μmol/L ,P <0 .0 1) ,SOD活性增加 (36 0 .6 0± 70 .33vs185 .0 0± 4 9.75U/L ,P <0 .0 1) ,血浆中NO2 -/NO3 -含量升高 (5 3.2 8± 5 .34vs 32 .2 5± 6 .4 8μmol/L ,P <0 .0 1)。②PC2 组与IR2 组比较 ,两组在心肌梗死范围 ,室性心律失常发生率方面均无明显差异 ,冠脉流出液中CK含量、组织中MDA含量及SOD活性测定亦无明显差异。结论 :远距预处理对在体心脏缺血再灌注损伤具有心肌保护作用 ,而经历预处理的离体心脏则无此作用 ,提示远距预处理对心脏I/R损伤的保护作用可?     

Dissociation of stress-activated protein kinase (p38-MAPK and JNKs) phosphorylation from the protective effect of preconditioning in vivo

The aim of the present study was to examine and compare the role of the stress-activated protein kinases in ischemic and stretch-induced preconditioning. A model of anesthetized rabbits was used, and the preconditioning protocol included one or three cycles of short ischemia/reperfusion, or short mechanical stretch with acute pressure overload without or with the addition of the stretch blocker gadolinium. Infarct size was determined after 2h reperfusion and p38 MAPK and JNKs phosphorylation was determined after 20 min of prolonged ischemia. Preconditioning stimuli were equally effective in reducing the infarct size (14.2+/-3.4%, 12.9+/-3.0%, 15.9+/-3.3%, P<0.01 vs control). The addition of the stretch channel blocker gadolinium abrogated the effect of stretch preconditioning only, without any effect on ischemic preconditioning. Comparing p38-MAPK and p46/p54 JNKs phosphorylation in the ischemic and non-ischemic regions of the heart at the time of sustained ischemia, activation was observed in the ischemic or mechanically preconditioned groups compared with the control. The addition of gadolinium abolished this activation. The above results indicate that the phosphorylation of p38-MAPK and p46/p54 JNKs is increased in preconditioning but this effect can be dissociated from the protective effect of ischemic preconditioning. Activation of the stress-activated protein kinases may be related to the increased contracture, a characteristic of ischemic preconditioning.     

川芎嗪预处理对清醒大鼠心肌缺血再灌注损伤的保护作用

目的 :用心肌缺血预处理的整体动物模型 ,观察川芎嗪预处理对清醒大鼠心肌缺血灌注损伤所致心律失常、心肌梗塞面积、乳酸脱氢酶和磷酸肌酸激酶活性的保护作用。方法 :先将实验动物麻醉 ,在人工呼吸状态下 ,开胸 ,左主动脉下穿线。然后 ,缝合胸腔。术后第 6d ,进行实验。单纯缺血再灌注组 :结扎冠脉 30min ,其后再灌 12 0min ;缺血预处理组 :冠脉结扎 5min ,再灌 5min ;然后 ,再次结扎冠脉 30min ,其后再灌 12 0min ;药物组 :川芎嗪 2 0mg·kg- 1 和 40mg·kg- 1 分别连续静脉给药 5min ;5min后 ,结扎冠脉 30min ,其后再灌 12 0min ;结果 :川芎嗪降低缺血和再灌时间VF和VT的发生 ,其发生率为 37 5 % ;使心肌梗塞面积缩小 ,乳酸脱氢酶和磷酸肌酸激酶的释放减少 ;上述指标与单纯缺血再灌注组相比 ,均有显著性差异。其结果与缺血预处理(冠状结扎 5min ,再灌 5min)对心肌缺血再灌注损伤产生的保护作用一致。结论 :川芎嗪通过预处理途径对清醒大鼠心肌缺血再灌注损伤所致心律失常、心肌梗塞面积、乳酸脱氢酶和磷酸肌酸激酶活性产生保护作用。     

Fetal asphyctic preconditioning in rats results in a preserved placental inflammatory phenotype at birth

IntroductionPerinatal asphyxia (PA) is a major cause of neonatal mortality and morbidity. Research has shown that in rats fetal asphyxia (FA) can provoke neuroprotection against a subsequent more severe perinatal asphyctic insult. This is called fetal asphyctic preconditioning (PC). Our objective was to investigate alterations in the placental inflammatory phenotype associated with PC.MethodsFA was induced in the rat at embryonic day 17 by reversibly clamping the uterine circulation and PA was induced at birth by submersion of the uterine horns in a saline bath for 19 min. The effect of PC was studied by inducing FA at E17, followed by PA at E21. Placental TNF-α, IL-1β, IL-6 and IL-10 mRNA and protein levels were measured by qPCR and ELISA.ResultsIL-1β mRNA increased in the labouring FA group, but IL-1β protein decreased after both FA and PA. In the PC group, IL-1β mRNA and protein levels were similar to controls. IL-6 protein increased 6 h after FA, however decreased 24 h after FA. IL-6 mRNA was higher in the labouring PA group. IL-10 protein decreased 24 h after FA. At birth, IL-10 mRNA increased in the PA group; however, IL-10 protein decreased in both the PA and the FA group. In the PC group, IL-10 mRNA and protein were similar to control levels.DiscussionDepleted protein concentrations of IL-10 and IL-1β after one single asphyctic insult were reversed after fetal asphyctic PC. In addition, PC placentas showed less up-regulation of IL-6 mRNA compared to the PA ones. This modulated placental inflammatory phenotype might contribute to the improved neonatal outcome showed after fetal asphyctic PC.     

1，6—二磷酸果糖预处理对离体大鼠心肌缺血再灌注损伤的保护作用

目的:观察1,6-二磷酸果糖(FDP)预处理对离体大鼠心肌缺血再灌注损伤的保护作用。方法:随机分成两组应用Iangendorff灌注装置用Krehs-Ring(K-R)液和K-R液加FDP5mmol·L~(1)对大鼠心脏进行缺血前预处理10分钟,缺血20分钟和再灌注20分钟实验,观察每期左室舒张未期压(LVEDP)、心肌组织内二醛(MDA)含量、超氧歧化物酶(SOD)的活性。Wistar大鼠心脏48个,每8个一组进行对照组和FDP组对比观察。结果:在缺血前期FDP组LVEDP和MDA无明显差异,缺血期FDP组MDA变化与对照组比较明显下降(P<0.01),再灌注期FDP组LVEDP和MDA明显下降(P<0.05),在FDP组SOD活性明显增高(P<0.01)。结论:FDP预处理具有提高大鼠心肌耐缺氧力,对大鼠心肌缺血再灌注损伤具有保护作用,该保护作用的机制可能与清除氧自由基功能有关。     

异氟醚麻醉对内毒素诱导的大鼠急性肺损伤的预处理效应

目的：探讨异氟醚醉对内毒素诱导的大鼠急性肺损伤的预处理效应，方法：内毒素经股静脉注射Wistar大鼠复制急性肺损伤模型。动物分为：对照组（C组）、单纯异氟醚预处理组（SIso组）内毒素（LSP组）2小时，4小时、8小时组异氟醚预处理＋内毒素（Iso＋LPS组）2小时、4小时、8小时组，观察大体标本，组织病理、肺泡灌洗液中性粒细胞比，蛋白含量，肺湿／干重比，肺血管通透性。结果：LPS组、Iso＋LPS组肺泡灌洗液中中性粒细胞比，蛋白含量均较Ｃ组和SIso组显著增加（P＜0．01）Iso＋LPS组肺泡灌洗液中中性粒细胞比，蛋白含量与LPS组比没有显著差异（P＞0．05）。LPS组和Iso＋LPS组肺湿／干重比、肺血管通透性显著高于C组和SIso组（P＜0．01），而LPS组和Iso＋LPS组两组间无显著差异（P＞0．05）。结论：内毒素可引起严重的急性肺损伤，而异氟醚麻醉对内毒素诱导的急性肺损伤的预处理效应不明显。     

Criteria for a mediator or effector of myocardial preconditioning: Do KATP channels meet the requirements?

Conclusions A set of criteria have been presented which we feel need to be met before one can assign an important role for a particular endogenous mediator, ion channel or enzyme as an important component of ischemic PC and evidence has been presented to suggest that the KATP channel meets most of the criteria listed. Obviously, this list is not all conclusive and other important factors will evolve as we increase our understanding of this fascinating phenomenon of ischemic PC.     

Preconditioning and its clinical potential

Preconditioning is emerging as a simple, safe and highly effective means of attenuating local and systemic effects of medical and surgical insult. Its enormous potential has not yet been harnessed and ongoing work will continue to bring it to the fore. This article covers the history, development and future clinical potential of preconditioning with particular regard to surgical insult.     

Cardioprotection by breathing hyperoxic gas—relation to oxygen concentration and exposure time in rats and mice

Objectives: Breathing a hyperoxic gas (≥95% O₂) protects against ischaemia-reperfusion injury in rat and mouse hearts. The present study investigated how oxygen concentration and duration of hyperoxic exposure influenced cardioprotection, and whether hyperoxia might induce delayed cardioprotection (after 24 h). Methods: Animals were kept in normal air or in a hyperoxic environment, and their hearts were isolated and Langendorff-perfused immediately or 24 h thereafter. Global ischaemia was induced for 25 min in rats and 40 min in mice, followed by 60 min of reperfusion. Infarct size was determined by triphenyl tetrazolium chloride staining. Results: In rats exposure to ≥95, 80, and 60%, but not to 40% of oxygen immediately before heart isolation and perfusion improved postischaemic functional recovery. Eighty or more percent of oxygen also reduced infarct size. A preconditioning-like effect could be evoked by 60 or 180 min of hyperoxia, giving both immediate and delayed protection. In the mouse heart protection could be induced by pretreatment for 15 or 30, but not by 60 min with ≥95% oxygen. The protective effect of hyperoxia in mice could be evoked in the immediate model only. Conclusions: Hyperoxia protects the isolated rat and mouse heart against ischaemia-reperfusion injury, but some species-different responses exist. The protection depends on both oxygen concentration in inspired air, and duration of hyperoxic exposure.