腺苷预适应对缺血再灌注损伤的保护作用

目的：观察预适应（缺血及腺苷）对大鼠下肢缺血再灌注后心、肺损伤的保护作用。方法：雄性SD大鼠随机分4组,每组8只。行腹主动脉下端阻断及再灌注各120min。组I为手术对照组。组Ⅱ在缺血再灌注前先行阻断腹主动脉5min后开放5min,共4次。组Ⅲ麻醉后经颈静脉持续滴注 腺苷生理盐水溶液。组Ⅳ为假手术对照组。4组均于麻醉后经舌静脉注入伊文氏兰（Evank's blue dye)溶液,动脉插管测定再灌注后的平均动脉压（MAP）。实验终点取心、肺组织行病理检查,心肌ATP酶,心、肺组织丙二醛（malonyldiadehyde,MDA)含量及Evan氏兰含量测定。结果：组Ⅰ、Ⅲ再灌注后MAP均显著低于组Ⅱ、组Ⅳ（P＜0．05）,组Ⅰ、Ⅲ间,组Ⅱ、Ⅳ间无显著性。组Ⅰ心肌ATP酶（包括Na^ K^ ATPase,Mg^2_ATPase及Ca^2 ATPase)活力均低于余3组,余2组间2,2比较均无显著差异。组Ⅰ心,肺组织MDA含量显著高于余3组,余3组间2,2比较均无显著差异。组Ⅰ肺Evan氏兰含量显著高于Ⅱ、Ⅲ、Ⅳ组,组Ⅱ、Ⅲ高于组Ⅳ,组Ⅱ、Ⅲ间无显著差异。结论：缺血和腺苷预适应能改善大鼠下肢缺血再灌注后心,肺组织和功能损伤。     

缺血预适应对肝脏缺血再灌注损伤的保护作用

自 198 6年Ｍｕｒｒｙ等[1] 在犬心模型上证实预先给予几次短暂心肌缺血 /再灌注 (Ｉ/Ｒ)能提高心肌对随后长时间冠脉阻断所致损伤耐受力 ,并称此现象为缺血预适应 (ｉｓｃｈｅｍｉｃｐｒｅｃｏｎｄｉｔｉｏｎ ,ＩＰ )。在随后人们大量的研究中发现多次短暂Ｉ/Ｒ不仅对心脏随后长期Ｉ/Ｒ损伤有保护作用 ,而且对肝脏及其它器官Ｉ/Ｒ损伤同样有保护作用。ＩＰ对肝脏Ｉ/Ｒ损伤的保护作用机制尚未完全明确 ,目前认为与腺苷、蛋白激酶Ｃ以及热休克蛋白等多种因素密切相关。本文就ＩＰ对肝脏Ｉ/Ｒ损伤的保护作用主要机制作一综述。1　腺苷受体的激…     

缺血预适应心肌保护作用的神经递质调节

缺血预适应是指心脏遭受短暂缺血后能耐受随后较长时间缺血损伤,是近年发现的一种预防心肌缺血损伤的有效措施。缺血预适应的心肌保护作用是心脏释放内源性心血管活性物质所介导。神经递质（儿茶酚胺、乙酸胆碱、降钙素基因相关肽、阿片肽等）可能是介导缺血预适应的内源性心肌保护物质。外源性应用神经递质能模拟缺血预适应的心肌保护作用。神经递质可同其它内源性活性物质相互作用。神经递质介导缺血预适应可能是通过与其相应受体结合,触发细胞内信息转导途径,激活蛋白激酶C产生心肌保护作用。     

远端缺血预适应对肠缺血再灌注损伤防护作用的研究

目的 通过建立大鼠远端缺血预适应(RIPC)和肠缺血再灌注损伤模型,探讨RIPC对肠缺血再灌注损伤是否有防护作用.方法 雄性SD大鼠分为肠缺血再灌注(L/R)组(8只)、RIPC组(8只)和假手术组(Sham组,5只).用充气套囊加压阻断右侧上下肢体血供5 min后放气恢复血供5 min的方法重复3次首先建立大鼠肢体缺血预适应模型.后经正中剖腹,阻断腹腔干动脉和肠系膜上动脉30 min后,恢复血运2h制作鼠肠缺血再灌注模型.取肠组织分别作苏木素-伊红染色、聚腺苷二磷酸核糖(PAR)免疫组织化学染色、原位凋亡检测、髓过氧化酶( MPO)活性和丙二醛检测.结果 肠组织损伤评分、PAR阳性表达率、MPO活性和丙二醛水平,I/R组均较Sham组明显增高[(4.65±0.82)分比(0.56±0.48)分,(23.8±2.8)％比(5.1±0.8)％;(330±15)U/g比(24±5)U/g;(248±15)μmol/( L· mg)比(36±7)μmol/(L·mg),均P＜0.05];RIPC组上述指标[(2.92±0.74),(16.8±3.1)％,(218±17) U/g,(121±13) μmol/(L· mg)]均明显低于I/R组,但仍高于Sham组(P＜0.05).结论 RIPC可能会通过抑制肠炎症反应、脂质过氧化和降低PARP激活程度来减轻I/R后小肠组织损伤.     

缺血预适应对急性脑梗死脑损伤的保护作用

目的观察缺血预适应（IP）对急性脑梗死脑损伤的保护作用。方法选取急性脑梗死患者110例,根据患者梗死前是否出现短暂性脑缺血发作分为对照组和IP组,每组56例。2组均给予对症治疗,比较2组临床疗效、脑梗死体积、NIHSS评分、BI指数评分。结果治疗后对照组和IP组总有效率分别为72．2％和91．1％、梗塞灶体积分别为（4．84±2．26）cm^3和（3．42±2．15）cm^3、NIHSS评分分别为（20．61±3．12）和（13．25±2．86）、BI指数评分分别为（36．72±2．34）和（69．08±4．67）,差异均有统计学意义（g〈0．05）。结论缺血预适应能够明显提高临床疗效,缩小梗死灶体积,减轻神经功能缺损程度及加强患者生活活动能力,具有良好的神经保护作用。     

无创性肢体缺血预适应对大鼠心脏的保护作用

目的研究无创性肢体缺血预适应(RIP)对大鼠缺血/再灌后心脏损伤的影响。方法采用无创性后肢缺血预适应的方法,观察其对心肌缺血/再灌后心脏生理学(HR、MAP、ST段)、室性心律失常的出现时间和持续时间的影响以及其对心肌缺血/再灌后梗死面积和形态学改变的影响。结果与对照组比较,处理组对心肌缺血/再灌后HR和MAP的影响差异无显著性,但是RIP能明显降低ST段的抬高幅度,推迟室性心律失常出现的时间,缩短持续时间,并且能减少心肌梗死面积,降低心肌细胞的肿胀、减少间质出血和炎性细胞的浸润。结论RIP对心肌损伤具有保护作用。     

丹参联合缺血预适应对缺血性心肌损伤的保护作用

目的:研究丹参(SM)联合缺血预适应(IP)对缺血性心肌损伤的保护作用.方法:以整体麻醉SD大鼠心脏冠状动脉左前降支结扎/松开作为缺血/再灌注动物模型,观察对心律失常程度和心肌梗塞范围的影响。结果:IP能减轻复灌性心律失常的严重程度,缩小心肌梗塞范围;SM能缩小心肌梗塞范围;SM联合IP与单纯IP比较,心肌梗塞范围进一步缩小;SM联合IP与单纯SM比较,心律失常严重程度和心肌梗塞面积均进一步减小。结论:SM能加强IP的心肌保护作用     

丹参联合缺血预适应对缺血性心肌损伤的保护作用

目的：研究丹参（SM）联合缺血预适应（IP）对缺血性心肌损伤的保护作用。方法：以整体麻醉SD大鼠心脏冠状动脉左前降支结扎／松开作为缺血／再灌注动物模型，观察对心律失常程度和心肌梗塞范围的影响。结果：IP能减轻复灌性心律失常的严重程度，缩小心肌梗塞范围；SM能缩小心肌梗塞范围；SM联合IP与单纯P比较，心肌梗塞范围进一步缩小；SM联合IP与单纯SM比较，心律失常严重程度和心肌梗塞面积均进一步减小。结论：SM能加强IP的心肌保护作用。     

无创性肢体缺血预适应对大鼠心脏的延迟保护作用

目的：研究无创性肢体缺血预适应（RIP）对大鼠缺血再灌后心脏损伤的影响。方法：通过连续3d每天1次3个循环下肢无创性缺血5min再灌5min建立RIP模型。实验分4组：假手术组；缺血再灌（I／R）组；心肌缺血预适应（CIP）组；RIP组。观察RIP对24h后I／R后心脏生理学、室性心律失常的出现时间和持续时间的影响以及其对I／R后梗死面积和形态学改变的影响。结果：与假手术组比较，I／R组ST段明显抬高（P〈0．01），并且有室性心律失常、梗死的出现，心肌细胞的肿胀、炎性细胞的浸润等表现。而CIP和RIP能明显改善模型组受损心肌的状态，减少心肌耗氧量，降低ST段的抬高幅度，推迟室性心律失常出现的时间，缩短持续时间，降低心律失常的发生率，减少心肌梗死面积（P〈0．01），并能减少心肌细胞的肿胀、间质出血和炎性细胞的浸润。结论：RIP对大鼠心肌损伤具有较好的延迟保护作用。     

降钙素基因相关肽介导大鼠后肢缺血预适应的保护作用

目的：研究降钙素基因相关肽（ＣＧＲＰ）介导缺血预适应对血管内皮的保护。方法：大鼠后肢缺血２ｈ后，观察乙酰胆碱诱导血管内皮依赖性舒张反应。结果：缺血不影去甲蛹 腺素的缩血管效应，但能显著削弱乙酰胆碱的舒血管效应。缺血预适应能阻止长时间缺血对惭酰胆碱舒血管效应的抑制作用，这种保护作用可被反复应用辣椒素耗竭ＣＧＲＰ所取消。急性应用辣椒素促进ＣＧＲＰ释放或外源性应用ＣＧＲＰ均可产生预适应样的保护作用。结论     

ATP敏感性钾通道参与兔脊髓缺血预处理的保护作用

目的　探讨ATP敏感性钾通道是否参与兔脊髓缺血预处理的保护作用。方法　 2 7只♂新西兰大白兔随机分成3组 (n =9) :即缺血组 (IC组 )、缺血预处理组 (IPC组 )及格列本脲 (glibenclamide ,ATP敏感性钾通道阻断剂 ) +缺血预处理组 (G +I组 )。IC组夹闭兔腹主动脉肾下段 2 0min ,复制兔脊髓缺血模型 ;IPC组预先使脊髓缺血 6min ,3 0min后再次阻闭兔腹主动脉肾下段 2 0min ;G +I组在缺血预处理前 2 0min静脉给予格列本脲 2mg·kg- 1,其他处理同IPC组。再灌注后 8、12、2 4和 48h分别对动物神经功能评分 ;再灌注 48h后 ,处死动物取脊髓 (L5～ 7) ,制作标本行组织病理学观察。结果　IPC组神经功能评分各时间点均高于IC组及G +I组 (P <0 0 5) ;与IC组及G +I组相比 ,IPC组脊髓前角正常神经细胞数明显增多 (P <0 0 1) ;IC组与G +I组在各时间点的神经功能评分及脊髓前角正常神经细胞数差异都无显著性 (P >0 0 5)。结论　兔脊髓缺血预处理的保护作用与ATP敏感性钾通道密切相关。     

脊髓腺苷受体介导侧脑室吗啡预处理对大鼠缺血后心肌的保护作用

目的探讨脊髓腺苷受体在侧脑室吗啡预处理对大鼠心肌缺血/再灌注损伤的保护作用中的介导作用以及与心肌缺血/再灌注损伤所引起的炎症反应的关系。方法健康♂SD大鼠54只,随机分为假手术组(Sham组)、对照组(CON组)、吗啡预处理组(MPC)、腺苷体阻断剂茶碱(theophylline,THE)+吗啡预处理组(MPC+THE组)、另设茶碱自身对照组,除茶碱自身对照组(6只)外,其他每组12只。每组观察指标包括:平均动脉压(MAP)、心率(HR),计算平均动脉压和心率乘积(RPP);心肌缺血危险区(AAR)、梗死区(IS)的体积,心肌梗死面积以IS/AAR表示;免疫组化测定心肌组织细胞间黏附分子(ICAM-1)的表达水平。结果与CON组相比,MPC组的IS和IS/AAR均明显下降(P<0.01),MPC+THE组分别明显低于CON组(P<0.01),高于MPC组(P<0.01),THE自身对照组与CON组相比差异无显著性(P>0.05);CON组心肌中的ICAM-1的表达水平明显高于Sham组(P<0.01),MPC组心肌组织中的ICAM-1的表达水平明显低于CON组(P<0.01),而MPC+THE组心肌组织中的ICAM-1的表达水平高于MPC组(P<0.01),低于CON组(P<0.01)。结论侧脑室吗啡预处理可以上调大鼠脊髓腺苷受体的激动水平,后者通过抑制心肌缺血/再灌注损伤的炎症反应,部分介导了侧脑室吗啡预处理对大鼠心肌缺血/再灌注损伤的保护作用。     

肢体缺血预处理对大鼠肝缺血-再灌注损伤的延迟性保护作用

目的观察肢体缺血预处理(LIPC)对大鼠肝缺血-再灌注(I-R)损伤的延迟性保护作用。方法雄性SD大鼠36只,随机分为对照组(S组),I-R组,LIPC组,每组12只。S组仅行开腹,不作其他处理;I-R组行肝缺血1h,再灌注3h;LIPC组先行双后肢缺血5min,反复3次24h后行肝缺血1h,再灌注3h。手术完毕,腹主动脉采血用于检测总超氧化物歧化酶(T-SOD)、丙二醛(MDA)、血清ALT与AST;切取肝组织,测定肝脏的湿干比(W/D),免疫组化检测肿瘤坏死因子α(TNF-α)的表达,同时光电镜观察肝组织显微、超微结构的变化。结果与I-R组比较,LIPC组T-SOD活性增加(P<0.01),MDA水平、ALT、AST、W/D值及TNF-α的阳性表达均明显降低(P<0.01),肝脏的显微及超微结构损伤减轻。结论 LIPC对大鼠肝脏I-R损伤有明显的延迟性保护作用。其机制可能与增加机体抗氧化能力、抑制肝脏炎症反应、减轻肝脏水肿、抑制TNF-α的表达和改善肝组织微循环有关。     

Down regulation of cyclooxygenase-2 is involved in delayed neuroprotection by ischemic preconditioning in rats

Aim: To examine whether the prostaglandins (PGs) pathway is involved in triggering delayed neuroprotection by ischemic preconditioning (IPC) and evaluate the effects of IPC on cyclooxygenase-2 (COX-2) expression following focal cerebral ischemia and reperfusion in rats. Methods: IPC was induced by 10min of saline infusion into the left internal carotid artery with the right common carotid artery clamped at the same time. Middle cerebral artery occlusion (MCAO) and reperfusion model was prodt:ced using intraluminal filament method. Results: IPC 48h priorto MCAO significantly reduced infarct area as compared with MCAO alone. A nonselective inhibitor of COX indomethacin (3mg/kg ip) applied 1h prior to or 1h after IPC failed to affect its protective effects. IPC had no direct effect on the cortex COX-2 mRNA and protein expression 72h later, but decreased the expression of COX-2 mRNA and protein following ischemia and reperfusion insult. Conclusion: PGs pathways was not involved in triggering delayed neuroprotection by IPC, and IPC induced down-regulation of COX-2 following focal cerebral ischemia and reperfusion in rats in vivo.     

Adenosine and inosine release during hypoxia in the isolated spinal cord of neonatal rats

BACKGROUND AND PURPOSE

Adenosine and inosine accumulate extracellularly during hypoxia/ischaemia in the brain and may act as neuroprotectants. In spinal cord, there is pharmacological evidence for increases in extracellular adenosine during hypoxia, but no direct measurements of purine release. Furthermore, the efflux pathways and origin of extracellular purines are not defined. To characterize hypoxia-evoked purine accumulation, we examined the effect of acute hypoxia on the extracellular levels of adenosine and inosine in isolated spinal cords from rats.

EXPERIMENTAL APPROACH

Extracellular adenosine and inosine concentrations were assayed in an in vitro preparation of the isolated spinal cord of the neonatal rat by HPLC.

KEY RESULTS

The extracellular level of inosine was about 10-fold higher than that of adenosine. Acute hypoxia (10 min) caused a temperature-dependent increase in these two purines, which were inhibited by an increase in external Ca²⁺, but not by several inhibitors of efflux pathways or metabolic enzymes of adenine nucleotides. Inhibitors of adenosine deaminase or the equilibrative nucleoside transporter (ENT) abolished the hypoxia-evoked increase in inosine but not adenosine. The inhibition of glial metabolism abolished the increase of both purines evoked by hypoxia but not by oxygen-glucose deprivation, hypercapnia or an adenosine kinase inhibitor.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that hypoxia releases adenosine itself from intracellular sources. Inosine formed intracellularly may be released through ENTs. During hypoxia, astrocytes appear to play a key role in purine release from neonatal rat spinal cord.     

系统低温对犬脊髓缺血性损伤的保护作用

目的:评价系统低温对犬脊髓缺血损伤的保护作用并探讨其作用机制。方法:18只杂种犬随机分为3组,实验组1、实验组2和实验组3,每组6只。建立犬脊髓缺血损伤模型,实验组1常温下阻断主动脉40min,实验组2在30℃下阻断40min,实验组3在24℃下阻断40min,40min后开放主动脉。术后24h按Tarlov评分标准评价动物后肢神经功能,然后处死动物,取脊髓进行组织病理学检查。结果:实验组2和实验组3动物后肢神经功能评分明显高于实验组1(P<0.01);实验组2和实验组3光镜下脊髓病理改变轻微,而实验组1较重,相比病理评分有显著性差异(P<0.01)。结论:系统低温对犬脊髓缺血性损伤具有明显的保护作用,且深度低温优于中度低温。     

无创性延迟肢体缺血预适应对大鼠脑缺血再灌注皮层的保护作用

目的：研究无创性延迟肢体缺血预适应（NDLIP）对大鼠脑缺血再灌注损伤的保护作用。方法：通过连续3d,每天1次3个循环左后肢无创性5min缺血、5rain再灌注,建立NDLIP模型。实验分4组：假手术组（sham）、缺血再灌注组（I／R）、早期脑缺血预适应＋I／R组（ECIP＋I／R）、NDLIP＋I／R组。观察其对脑缺血／再灌注的神经缺损症状,脑梗死范围,超氧化物歧化酶（SOD）,谷胱甘肽过氧化物酶（GSH—PX）活力,黄嘌呤氧化酶活力（XOD）,丙二醛（MDA）含量影响。结果：与I/R组相比,ECIP＋I／R组及NDLIP＋I／R组缺血1h,再灌注24h后评分有非常显著的降低;脑梗死范围显著减小。与I／R组比较,ECIP＋I／R组和NDLIP＋I／R组的T-SOD和Mn—SOD活力、GSH—PX活力均升高;XOD活力明显降低,MAD含量明显减少;ECIP＋I／R组和NDLIP＋I／R组间差异无统计学意义。结论：NDLIP可降低I／R对神经的损伤、减小脑梗死范围、提高脑组织抗氧化能力,减少I／R对脑组织的损伤。     

Actions of specific adenosine receptor A1 and A2 agonists and antagonists in recovery of phrenic motor output following upper cervical spinal cord injury in adult rats

1. Previous studies from our laboratory have established that a latent respiratory motor pathway can be activated to restore function to a hemidiaphragm paralysed by upper cervical (C2) spinal cord hemisection during a reflex known as the 'crossed phrenic phenomenon'. In addition, theophylline, a general adenosine A1 and A2 receptor antagonist, can activate the latent pathway by acting centrally through antagonism at adenosine receptors. 2. The present study was designed to assess the relative contributions of adenosine A1 and A2 receptors in inducing functional recovery in our model of spinal cord injury. Specific adenosine A1 and A2 agonists and antagonists were used in an electrophysiological study. 3. Our results demonstrate that, in hemisected rats, systemic administration of the adenosine A1 receptor-specific antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) restores, in a dose-dependent manner, phrenic nerve respiratory related output that is lost following hemisection. Furthermore, DPCPX augments respiratory activity in non-injured animals. The A2 receptor agonist CGS-21680 mediates its effects by predominantly acting on peripheral rather than central nervous system (CNS) receptors. CGS-21680 modulates respiratory related phrenic nerve activity in non-injured animals by enhancing tonic activity, but does not induce recovery of phrenic nerve activity in hemisected animals in the majority of cases. When CGS-21680 was administered prior to DPCPX in hemisected rats, the magnitude of recovery of respiratory function was significantly greater than that elicited by DPCPX alone. However, when the A2 receptor agonist was administered after DPCPX, the magnitude of recovery was virtually unchanged, whereas activity in the right phrenic nerve was significantly enhanced. The A1 receptor agonist N6-cyclohexyladenosine depressed respiratory activity in non-injured, as well as hemisected, rats. The A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine did not affect respiratory activity. 4. We conclude that while antagonism at central adenosine A1 receptors mediates functional restitution in hemisected animals, activation of A2 receptors located outside of the CNS subserves the A1 receptor-mediated respiratory recovery.     

腺苷及其受体激动剂对不稳定型心绞痛患者IL-18的影响

目的观察腺苷及腺苷受体激动剂对不稳定型心绞痛(UAP)患者白介素(IL)-18的影响,探讨腺苷受体的作用机制。方法选取15例UAP患者(UAP组)及15例健康志愿者(对照组),采用腺苷及腺苷受体激动剂干预全血标本,双抗体夹心酶联免疫吸附法(ELISA)检测IL-18。结果低浓度腺苷(1~100μmol/L)对UAP组IL-18表达有增强效应,高浓度(1 mmol/L)有抑制效应。腺苷A1受体激动剂与A3受体激动剂对IL-18表达有增强效应,而腺苷A2a受体激动剂对IL-18表达有抑制效应,腺苷A2b受体激动剂对IL-18表达未见明显效应。结论腺苷在低浓度时对UAP患者IL-18的表达有促进作用,可能通过腺苷A1和A3受体发挥效应;高浓度时有抑制作用,可能通过腺苷A2a受体发挥作用。     

Spasticity therapy reacts to astrocyte GluA1 receptor upregulation following spinal cord injury

For almost three decades intrathecal baclofen therapy has been the standard treatment for spinal cord injury spasticity when oral medication is ineffective or produces serious side effects. Although intrathecal baclofen therapy has a good clinical benefit-risk ratio for spinal spasticity, tolerance and the life-threatening withdrawal syndrome present serious problems for its management. Now, in an experimental model of spinal cord injury spasticity, AMPA receptor blockade with NGX424 (Tezampanel) has been shown to reduce stretch reflex activity alone and during tolerance to intrathecal baclofen therapy. These results stem from the observation that GluA1 receptors are overexpressed on reactive astrocytes following experimental ischaemic spinal cord injury. Although further validation is required, the appropriate choice of AMPA receptor antagonists for treatment of stretch hyperreflexia based on our recent understanding of reactive astrocyte neurobiology following spinal cord injury may lead to the development of a better adjunct clinical therapy for spasticity without the side effects of intrathecal baclofen therapy.

LINKED ARTICLE

This article is a commentary on Oshiro et al., pp. 976–985 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2010.00954.x