缺血后处理对保护皮瓣的作用机制研究

目的：缺血后处理已经在心、肾等器官上广泛应用,进行相关研究进一步探究缺血后处理对皮瓣有否保护作用。方法：健康成年新西兰大白兔,分为3组。A组为给予缺血后处理;B组为再灌注前5min给予A2A阻滞剂SCH58261＋缺血后处理。C组,直接应用微血管夹阻断腹壁浅血管持续缺血6h后,恢复正常血供。分别进行中性粒细胞浸润,MPO含量和皮瓣存活率检测。结果：新西兰大白兔完全存活。B、C组相比较,中性粒细胞计数以及MPO含量也未见统计学差别（P〉0.005）。实验组皮瓣存活面积比较,B与C相比较,无统计学意义（P〉0.005）,但是A与B、C相比较,上述指标两两之间都有统计学意义差别（P〈0.005）。结论：缺血后处理对皮瓣再灌注损伤有保护作用,该作用可能和A2A受体性质有关。     

缺血后处理激活自噬保护皮瓣机制研究

目的:缺血后处理皮瓣在临床上已经运用,开始相关研究探究缺血后处理对皮瓣保护机制。方法:健康成年新西兰大白兔,分为3组。A组为给予缺血后处理;B组为再灌注前5mi n给予自噬阻滞剂3-甲基腺嘌呤10μl+缺血后处理。C组,直接应用微血管夹阻断腹壁浅血管持续缺。6h后再灌。各组分别进行自噬指标Becl i n1、LC3免疫组化和皮瓣存活率检测。结果:新西兰大白兔完全存活。B、C组相比较,自噬Becl i n1、LC3免疫组化染色阳性细胞面积变化未见统计学差别(P>0.005)。实验组皮瓣存活面积比较,B与C相比较,无统计学意义(P>0.005),但是A与B、C相比较,上述指标两两之间都有统计学意义差别(P<0.005)。结论:缺血后处理对皮瓣再灌注损伤有保护作用,该作用可能和自噬激活有关。     

肝脏缺血后处理的保护作用机制

肝脏缺血后处理是指肝脏在长时间缺血后,在再灌注之前进行一次或数次短暂重复的缺血再灌注,能提高肝脏对长时间缺血的耐受性,减轻缺血再灌注损伤.近几年被证实为一种有效、可控制的新的减轻再灌注损伤的方法.肝脏缺血后处理的保护机制与保护肝窦内皮和肝脏细胞超微结构,减轻活性氧引起的细胞损伤及炎症反应,减轻细胞内及线粒体内钙超载,调控凋亡基因,改变线粒体离子通道开放状态等有关.本文就缺血后处理的机制作一简要综述.     

缺血后处理心肌保护作用的研究进展

缺血后处理（一个长时间缺血后,在再灌注开始时,通过反复短暂间断的缺血／再灌注而诱导的心肌保护现象）是最近提出的一种和缺血预处理一样有心肌保护作用的新的治疗措施,被认为是减少缺血／再灌注损伤的“末戏”。因为能够在缺血后再灌注时实施,可用于突发的不可预知的心肌缺血事件,有极大的基础研究意义和临床应用前景。现就其在心肌保护方面的研究作一简要综述。     

缺血后处理对骨骼肌缺血再灌注损伤的保护作用

任何组织的缺血,只要达到一定时间和程度,必然会引起组织细胞的损伤.1985年McCord经过研究发现,长时间的组织器官缺血后的再灌注是一把"双刃剑",首先是再灌注挽救了缺血的组织器官,以防止进一步的缺血损伤,然而不可控的再灌注也引起了组织器官的再灌注损伤,故此提出了缺血一再灌注损伤这一概念.骨骼肌是组成肢体的重要组织之一,同时它对缺血十分敏感,人类骨骼肌在室温下完全缺血2.25 h就会出现不可逆的功能损害.在骨科的临床工作中,动脉断裂栓塞、断肢再植、应用止血带时间过长,都有可能造成严重的骨骼肌缺血,随后发生缺血再灌注损伤,从而影响患者肢体的存活,甚至造成截肢的后果.     

缺血后处理对兔脊髓缺血-再灌注损伤的保护作用

目的研究缺血后处理是否可以减轻兔脊髓缺血再灌注的损伤。方法雄性新西兰大白兔30只,随机分为五组,每组6只。假手术组(N1组)仅行单纯手术操作但不阻闭腹主动脉;对照组(N2组)行单纯缺血再灌注;缺血后处理15s/30s/60s(PA/PB/PC组)分别于阻闭腹主动脉15min后,再灌注15s/30s/60s,缺血15s/30s/60s,反复3次。再灌注48h时对所有动物的后肢运动功能进行评分并行脊髓前角正常神经元计数。结果PB组再灌注48h后肢运动功能评分[3.5(2～4)分],明显高于N2组[2(1～3)分](P<0.05),其他各组与N2组相比差异无显著意义。脊髓前角正常神经元计数PB组为36.7±7.0,明显多于N2组25.7±4.3(P<0.01),而PA组18.2±2.2和PC组8.0±4.1则明显少于N2组(P<0.05)。结论缺血后处理对兔脊髓缺血再灌注损伤的作用取决于后处理时间,缺血后处理30s/30s对脊髓缺血再灌注损伤具有保护作用,而缺血后处理15s/15s和60s/60s会加重脊髓损伤。     

心肌保护新策略——缺血后处理

缺血后处理（ischernjc postconditioning）是近年来提出的一种新的心肌保护方法，即再灌注后对缺血心肌反复进行再缺血处理，以减轻缺血再灌注损伤。其机制可能与抑制氧自由基堆积、中性粒细胞黏附、心肌细胞凋亡和细胞内钙超载有关。由于缺血后处理可在不可预见的心肌缺血后进行，且操作方便，因此在临床上可能具有较大的应用价值。     

缺血后处理对小肠缺血再灌注损伤的保护作用

目的：观察缺血后处理减轻肠缺血再灌注引起的小肠及远隔脏器损伤的效果,并探讨其机制。方法将家兔48只随机分为假手术组、缺血再灌注组、缺血后处理组,每组16只。再灌注2 h 后采集各组动脉血、静脉血及部分肠道组织、肝、肺组织,测动脉血中 TNF-α、IL-1β、IL-6、IL-10水平,测静脉血中 ALT、AST、BUN,Cr、LDH、CK-MB 活性,测内毒素水平,测定血清及小肠、肝、肺组织 MDA、MPO、CAT、SOD 水平,HE 染色,观察肠黏膜损伤情况,细菌培养观察细菌易位率。结果与缺血再灌注组比较,缺血后处理组血清及小肠、肝、肺组织中 MDA、MPO 水平明显降低, SOD、CAT 水平明显升高,静脉血 ALT、AST、LDH、CK-MB、BUN 下降;动脉血中 TNF-α、IL-1β、IL-6、内毒素降低,IL-10水平升高,肠黏膜损伤评分明显降低。结论缺血后处理可以减轻肠黏膜损伤,减少内毒素易位,促进抗炎因子的激活,抑制炎性介质的过度释放,提升小肠组织及远隔脏器的氧自由基的抗氧化能力,减轻小肠及远隔脏器组织损伤。     

缺血后处理和缺血预处理对兔脊髓缺血再灌注损伤的保护作用

缺血预处理及后处理可减轻心肌缺血再灌注损伤，但对脊髓缺血再灌注损伤的作用有待进一步探讨。本研究拟观察缺血预处理、缺血后处理及二者联合应用对兔脊髓缺血再灌注损伤的保护作用。     

心肌保护新策略--缺血后处理

缺血后处理(ischemic postconditioning)是近年来提出的一种新的心肌保护方法,即再灌注后对缺血心肌反复进行再缺血处理,以减轻缺血再灌注损伤.其机制可能与抑制氧自由基堆积、中性粒细胞黏附、心肌细胞凋亡和细胞内钙超载有关.由于缺血后处理可在不可预见的心肌缺血后进行,且操作方便,因此在临床上可能具有较大的应用价值.     

芬太尼后处理、肢体远隔缺血后处理和缺血后处理对大鼠心肌缺血/再灌注初期室性心律失常的影响

目的 对比观察芬太尼后处理、远隔缺血后处理和缺血后处理3种干预措施抑制大鼠心肌缺血/再灌注初期室性心律失常作用的差别.方法 将73只成年雄性SD大鼠(体重250 g～350 g)麻醉后按随机数字表法随机分为9组:空白对照组(S组,n=5);对照组(C组,n=7);芬太尼后处理组(F组,n=9);肢体远隔缺血后处理组(R组,n=9);缺血后处理组(P组,n=8);联合应用芬太尼后处理和肢体远隔缺血后处理组(F-R组,n=9);联合应用芬太尼后处理和缺血后处理组(F-P组,n=8);联合应用肢体远隔缺血后处理和缺血后处理组(R-P组,n=9);联合应用芬太尼后处理、肢体远隔缺血后处理和缺血后处理组(F-R-P组,n=9).所有大鼠开胸后采用丝线套扎其冠状动脉左前降支(left anterior descending coronary artery,LAD)做成活结.除S组之外,所有大鼠接受局部心肌缺血30 min和再灌注60 min的处理.C组不采用任何干预措施;F组、F-R组、F-P组和F-R-P组在LAD结扎15 min时缓慢静脉注射芬太尼30 μg/kg;R组、F-R组、R-P组和F-R-P组在LAD结扎15 min时结扎大鼠双下肢造成肢体缺血10 min后恢复双下肢血流灌注;P组、F-P组、R-P组和F-R-P组开放实施再灌注的初期连续实施3个循环的开放LAD 20 s/阻断LAD 20 s的缺血后处理.记录缺血期和再灌期前30 min内的心律失常评分(AS评分)以及室性心动过速(ventricular tachycardia,VT)和心室纤颤(ventricular fibrillation,VF)的发生率和持续时间.结果 缺血期VT和VF的发生率、VT或VF的持续时间以及AS评分在C组、F组、R组、P组、F-R组、F-P组、R-P组和F-R-P组无统计学差异.C组、F组、R组、P组、F-R组、F-P组、R-P组和F-R-P组再灌注初期AS评分的中位数分别为4、2、2、1、2、1、1和2.与C组比较,其余各组再灌注初期室性心律失常发生显著减少;再灌注初期的VT持续时间和AS在F组和R组之间无统计学差异,但F-R组再灌注初期的VT持续时间则显著降低.与F组和R组比较,P组、F-R组、F-P组、R-P组和F-R-P组再灌注初期的VT持续时间和室性心律失常评分显著减低. 结论 与芬太尼后处理和远隔缺血后处理比较,缺血后处理可更有效抑制再灌注初期室性心律失常的发生.联合应用芬太尼后处理和远隔缺血后处理后,抑制心肌再灌注初期室性心律失常的作用相对增强.     

腺苷A_1受体激动剂后处理对兔心肌缺血-再灌注损伤的影响

目的 探讨腺苷A1受体激动剂(2-氯环戊腺苷,CCPA)后处理对兔心肌缺血-再灌注损伤的保护作用.方法 32只兔随机均分为四组:假手术组(S组,开胸后仅行左冠状动脉套线而不阻断160min)、缺血-再灌注组(IR组,行左冠状动脉前降支阻断40 min,再灌注120 min)、缺血后处理组(lPC组,结扎左冠状动脉前降支40 min,再通30 s,结扎30 s,重复3次,再灌注120 min)和CCPA后处理组(APC组,结扎左冠状动脉前降支40 min,开放左冠状动脉1 min内予以静推CCPA100 μg/kg,冉灌注120 min).分别于左冠状动脉前降支阻断前20 min(T1)、左冠状动脉前降支阻断20 min(T2)、左冠状动脉前降支阻断40 min(T3)、心肌再灌注1 h(T4)和心肌再灌注2 h(T5)抽取颈内动脉血测定血清心肌肌钙蛋白I(cTnI)含量.再灌注末抽血离心测定超氧化物歧化酶(SOD)、丙二醛(MDA),测定心肌梗死面积.结果 和IR组相比,IPC组和APC组再灌注各个时间点cTnI均降低(P<0.05);IPC组和APC组梗死面积均小于IR组(P<0.05);IPC组和APC组血清中sOD的活性高于IR组,MDA的含量低于IR组(P<0.05).结论 腺苷A1受体激动剂后处理具有类似缺血后处理的心肌保护作用.其机制可能是通过减少氧自山基的生成,增强心肌抗氧化能力.     

Reducing joint destruction due to septic arthrosis using an adenosine2A receptor agonist.

We assessed the efficacy of a new adenosine A2A agonist ATL146e, a potent inhibitor of white blood cell chemotaxis, to reduce cartilage damage in the treatment of septic arthrosis. A live septic arthrosis model was created using Staphylococcus aureus in rabbit knees. Animals were divided into five treatment groups: (1) untreated infected control, (2) antibiotics control, and antibiotics plus ATL146e for (3) 24, (4) 48, or (5) 72 h and assessed at 1, 4, and 7 days. Knees in all ATL146e treated animals exhibited no detectable effusion, and histologic examination revealed near normal cartilage and diminished synovial inflammatory response. Synovial WBC counts decreased with the addition of ATL146e when compared to infected and antibiotic controls. Histologic grading of osteochondral specimens demonstrated improved scores for animals treated with ATL146e compared to infected (p<0.00004) and antibiotics controls (p<0.05). Analysis of glycosaminoglycan content revealed significantly decreased loss of articular cartilage following infection in the ATL146e groups when compared to infected (p<0.03) and antibiotics controls (p<0.05). Addition of an adenosine A2A agonist to antibiotic therapy decreases joint inflammation and articular cartilage destruction without compromising bacterial clearance in rabbit knees following intraarticular bacterial infection. The use of adenosine agonists selective to the A2A receptor to augment conventional treatment of joint sepsis may be chondroprotective and ultimately help prevent arthrosis.     

Ischemia postconditioning protects dermal microvascular endothelial cells of rabbit epigastric skin flaps against apoptosis via adenosine A2a receptors

Background: It has been shown that endogenous adenosine-induced by ischemia postconditioning attenuates apoptosis in recent studies; however, they focus only on parenchymal cells. The detailed mechanism has not been clearly clarified in any research and the subtype of adenosine receptors involved remains unknown. In our study, dermal microvascular endothelial cells (DMECs) are used to explore the role of adenosine A_2a receptor in the anti-apoptotic effects of ischemic postconditioning.

Material and methods: The epigastric skin flaps of rabbits were elevated. After 4?h of ischemia, the flaps were either abruptly reperfused or postconditioned by six cycles of brief reperfusion (15s) and re-ischemia (15s). Adenosine A2a receptor agonist (CGS-21680) and antagonist (ZM-241385) were used separately in other groups. The apoptosis-related proteins and adenosine A2a receptors were determined by immunohistochemical staining. Then apoptosis index was calculated by TUNEL.

Results: Ischemia/reperfusion caused severe damages in DMECs of flaps as demonstrated by an increase in apoptosis index and an increase in expressions of apoptosis-related proteins, which can be significantly attenuated by IPC treatment or exposure to a selective adenosine A_2a receptor agonist (all p values <.05). Meanwhile, the anti-apoptosis effects of IPC can be blocked by a selective adenosine A_2a receptor antagonist. Statistical analysis revealed that the increase of apoptosis index closely correlated inversely with the relative increase of adenosine A_2a receptors (p?Conclusions: Ischemia postconditioning protects DMECs of rabbit skin flap against apoptosis via activation of adenosine A_2a receptors.     

腺苷A1受体系统在兔脑预缺血延迟相保护效应中的作用

目的 探讨腺苷A1受体系统在兔脑预缺血延迟相保护效应中的作用。方法 股动脉放血至平均动脉压35－40mmHg时,阻断双侧颈总动脉诱导脑缺血。脑缺血3min存活3d（预缺血处理）后、脑缺血10min（预缺血延迟相保护模型）;用腺苷A1受体激动剂氮6－环戊基腺苷（CPA）代替预缺血处理,用其拮抗剂8－环戊基－1,3－二丙基黄嘌呤（DPCPX）阻断该受体;免疫组化分析热休克蛋白70（SHP70）表达。观察缺血3d后海马CA1区正常神经密度和HSP70的表达。结果 （1）CPA能减轻脑缺血损害,但其保护作用不如预缺明显（约占后者的70％）,DPCPX阻断该受体后,预缺血延迟相保护作用消失;（3）3min脑预缺血神经元无损害,但伴HSP70明显表达;DPCPX阻断腺苷A1受体后,3min脑预缺血发生明显损害,且HSP70表达明显削弱。结论 （1）预缺血延迟相保护作用与腺苷A1受体系统激活有关;（2）DPCPX阻断预缺血延迟相保护作用的机制与削弱HSP70表达有关。     

Role of adenosine A2A receptor in organ-specific vascular reactivity following hemorrhagic shock in rats

Background

Previous studies have demonstrated differences among organs in terms of shock-induced vascular reactivity and a role for adenosine A2A receptors (A2ARs) in protection against ischemia/reperfusion injury. However, the contributions of A2ARs to organ-specific vascular reactivity and the protection of vascular responsiveness following shock are currently unknown.

Methods

We investigated the role of A2ARs in different arteries, including the left femoral artery (LFA), thoracic aorta (TA), superior mesenteric artery (SMA), right renal artery (RRA), pulmonary artery (PA), and middle cerebral artery (MCA), in hemorrhagic-shock rats.

Results

The vascular reactivities of the LFA, SMA, RRA, and MCA increased slightly during early shock and then gradually decreased, whereas those of the PA and TA decreased from the start of shock. Different blood vessels lost vascular reactivity at different rates compared with controls; the LFA had the highest rate of loss (64.51%), followed by the SMA (44.69%), TA (36.06%), PA (37.83%), and RRA (32.33%), whereas the MCA had the lowest rate (18.45%). The rate of loss of vascular reactivity in the different vessels was negatively correlated with A2AR expression levels in normal and shock conditions. The highly selective A2AR agonist CGS 21680 significantly improved vascular reactivity, hemodynamic parameters, and animal survival, whereas the specific antagonist SCH58261 further decreased the shock-induced reduction in vascular reactivity and hemodynamic parameters.

Conclusions

A2ARs are involved in the regulation and protection of vascular reactivity following shock. A2AR activation may have a beneficial effect on hemorrhagic shock by improving vascular reactivity and hemodynamic parameters.     

腺苷A1受体系统对兔脑缺血损伤的保护效应

目的　探讨腺苷A1 受体系统对兔脑缺血的保护作用。方法　家兔 2 4只随机分为对照组 (Ⅰ组 ,n =8)、缺血组 (Ⅱ组 ,n =8)和腺苷A1 受体激动药 +缺血组 (Ⅲ组 ,n =8) ,股动脉抽血至平均动脉压 35～ 40mmHg时 ,阻断双侧颈总动脉诱导脑缺血。观察术后第 3天海马CA1 区神经元密度。结果　 (1 )Ⅱ组神经元密度为 (76 50± 1 5 2 6)个 /毫米 ,显著低于Ⅰ组神经元密度 (2 0 8 1 3±1 1 0 8)个 /毫米 (P <0 0 5) ;而Ⅲ组神经元密度 [(1 30 78± 1 8 0 7)个 /毫米 ]明显高于Ⅱ组 (P <0 0 5)。结论　激活腺苷A1 受体系统能减轻脑缺血性损害     

肢体缺血后适应对小鼠脑缺血再灌注损伤的影响及其机制

目的 观察肢体缺血后适应对小鼠脑缺血再灌注的影响并探讨作用机制.方法 以小鼠为实验对象,建立小鼠大脑中动脉闭塞(MCAO)模型.实验中随机抽取了54只雄性小鼠,并将其随机分为3组:Sham组18只;缺血再灌注(I/R)组18只;I Postcond组18只.以高效液相色谱法(HPLC)对缺血脑组织中的匀浆谷氨酸(Glu)浓度进行检测.结果 脑缺血再灌注6h后,I Postcond 组的Glu浓度指标为5.4,I/R组的Glu浓度指标为8.3,I Postcond组较I/R组低,且差异有统计学意义(P＜0.01).24 h后,I Postcond组的Clu浓度指标为2.6,而I/R组的Glu浓度指标为3.4,虽仍然呈较低状态,但此时差异无统计学意义(P＞0.05).结论 Ⅰ Postcond的确存在延缓小鼠MCAO中的I/R损伤现象,细胞间隙之中的Glu清除加速作用或为对抗I/R损伤的机制.     

Attenuation of renal ischemia–reperfusion injury by postconditioning involves adenosine receptor and protein kinase C activation

Significant organ injury occurs after transplantation and reflow (i.e., reperfusion injury). Postconditioning (PoC), consisting of alternating periods of reperfusion and re‐occlusion at onset of reperfusion, attenuates reperfusion injury in organs including heart and brain. We tested whether PoC attenuates renal ischemia–reperfusion (I/R) injury in the kidney by activating adenosine receptors (AR) and protein kinase C (PKC). The single kidney rat I/R model was used. Groups: (1) sham: time‐matched surgical protocol only. In all others, the left renal artery (RA) was occluded for 45 min and reperfused for 24 h. (2) Control: I/R with no intervention at R. All antagonists were administered 5 min before reperfusion. (3) PoC: I/R + four cycles of 45 s of R and 45 s of re‐occlusion before full R. (4) PoC + ARi: PoC plus the AR antagonist 8‐ρ‐(sulfophenyl) theophylline (8‐SPT). (5) PoC + PKCi: PoC plus the PKC antagonist chelerythrine (Che). In shams, plasma blood urea nitrogen (BUN mg/dl) at 24 h averaged 23.2 ± 5.3 and creatinine (Cr mg/dl) averaged 1.28 ± 0.2. PoC reduced BUN (87.2 ± 10 in Control vs. 38.8 ± 9, P = 0.001) and Cr (4.2 ± 0.6 in Control vs. 1.5 ± 0.2, P < 0.001). 8‐SPT and Che reversed renal protection indices after PoC. I/R increased apoptosis, which was reduced by PoC, which was reversed by 8‐SPT and Che. Postconditioning attenuates renal I/R injury by adenosine receptor activation and PKC signaling.