High-potassium preconditioning enhances tolerance to focal cerebral ischemia-reperfusion injury through anti-apoptotic effects in male rats

Imbalances between cellular K⁺ efflux and influx are considered to be involved in cerebral ischemia-reperfusion (I/R) injury. High-potassium pretreatment alleviates this injury, but the underlying molecular mechanism is unclear. In this study, we sought to investigate whether high-potassium preconditioning enhances cerebral tolerance to I/R injury through an anti-apoptotic mechanism. Adult male Sprague-Dawley rats were randomly divided into four groups (n = 40/group): a sham-operated group, normal saline group (3.2 ml/kg saline, intravenous (IV)), and low-dose and high-dose potassium chloride (KCl) groups (40 and 80 mg/kg KCl solution, IV, respectively). Subsequently, the rats underwent 90 min of middle cerebral artery occlusion (MCAO) followed by 24 hr of reperfusion (MCAO/R). Neurological deficit scores, 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin and eosin staining, and TUNEL assay were used to assess neural injury. The expression of apoptotic proteins, brain potassium levels, mitochondrial function and oxidative stress were detected to explore the potential mechanism. After 24 hr of reperfusion, in both KCl treatment groups, neurological deficits and the cerebral infarct volume were reduced, and the apoptosis index of neurons was decreased. Furthermore, high-potassium preconditioning increased brain K⁺, adenosine triphosphate (ATP), cytochrome c oxidase (COX) levels, reduced malondialdehyde level, improved Na⁺/K⁺-ATPase, succinic dehydrogenase and superoxide dismutase activities, upregulated anti-apoptotic protein expression, and downregulated pro-apoptotic protein expression. This study suggests that high-potassium preconditioning enhanced cerebral tolerance to I/R injury in a rat MCAO/R model. The protective mechanism may involve apoptosis inhibition via preservation of intracellular K⁺ and improvement of mitochondrial function.     

Recipient hypertonic saline infusion prevents cardiac allograft dysfunction

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Protective Effects of a Hydrogen-Rich Preservation Solution in a Canine Lung Transplantation Model

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尼可地尔对老年糖尿病并STEMI患者直接PCI缺血再灌注的心肌保护效应

目的：探讨尼可地尔对老年糖尿病并急性ST段抬高心肌梗死（STEMI）患者直接经皮冠状动脉介入（PCI）缺血-再灌注损伤（IRI）的心肌保护效应。方法：选取老年糖尿病并STEMI患者124例，均符合直接PCI适应证，按照分层区组随机化原则分为对照组（62例）和尼可地尔组（62例）。对照组患者行常规PCI；尼可地尔组在对照组治疗的基础上，术前给予注射用尼可地尔以0.06 mg·kg^-1（限制3~4 mg/次）静注，术中2 mg冠状动脉内给药，并以4 mg·h^-1静脉泵注24 h，之后尼可地尔片5 mg/次，3次/d，口服6个月。于术前及术后监测两组患者：（1）心肌IRI指标：血清心肌肌钙蛋白I（cTnI）及超敏肌钙蛋白T（hs-cTnT）；心力衰竭指标：N末端脑钠肽前体（NT-pro BNP）；（2）冠状动脉微循环灌注指标：心肌梗死溶栓试验（TIMI）血流分级和校正的TIMI帧数（CTFC）；（3）再灌注心律失常（RA）；（4）超声心动图检查左心室室壁运动评分指数（WMSI）和左室射血分数（LVEF）；（5）术后6个月内主要不良心血管事件（MACE）；（6）术后6个月内药物不良反应。结果：（1）于PCI术后0，6，12，24 h及术后3，7 d，尼可地尔组的血清cTnI水平均明显低于对照组（F_组间=62.537，P_组间<0.01）；（2）PCI术后尼可地尔组TIMI血流分级优于对照组（Z=-2.227，P=0.026），CTFC低于对照组（t=5.937，P<0.001）；（3）PCI后14 d尼可地尔组的WMSI低于对照组（t=14.974，P<0.001），LVEF高于对照组（t=-5.268，P<0.001）；（4）于术后1，3，7，14 d，尼可地尔组的血清NT-proBNP水平均低于对照组（F_组间=54.818，P_组间<0.01）；（5）IRA开通后4 h内尼可地尔组RA的发生率低于对照组（χ²=9.325，P=0.002）；（6）术后6个月内尼可地尔组MACE发生率低于对照组（χ²=4.613，P=0.032）；（7）两组患者药物不良反应发生率比较（χ²=0.614，P=0.433），差异无统计学意义。结论：尼可地尔对老年糖尿病并STEMI患者直接PCI的IRI具有心肌保护效应，能有效改善PCI后的心脏血流灌注，减轻心肌的IRI，改善室壁运动及左心功能，减少RA的发生，降低短期MACE发生率，且安全性好。     

Pulmonary injury at the anhepatic phase without veno-venous bypass in portal hypertensive rats

Objective: In order to understand the characterization and evolution of pulmonary injury, a portal hypertension rat model was used to imitate the anhepatic phase during standard orthotopic liver transplantation without veno-venous bypass. Methods: In this study, 135 healthy male Wistar rats were selected; in which 15 rats were assigned in the normal control (NC) group and the remaining 120 rats were used to establish a recoverable prehepatic portal hypertension model, which were further evenly divided into eight groups after ischemia-reperfusion: portal hypertensive control group (PHTC), R0h, R6h, R12h, R24h, R48h, R72h, and R7d groups. Meanwhile, arterial blood pressure, dry-to-wet weight ratios of the lung, alanine aminotransferase (ALT) level in serum, arterial oxygen pressure (PaO₂), and myeloperoxidase (MPO) activity in lung tissue were measured. Morphology changes of the lung were observed using an optical microscope and a transmission electron microscope. Results: The portal hypertension rat model was successfully established three weeks after the first operation. These portal hypertensive rats could withstand 1 hour at the anhepatic phase. Pulmonary injury severity increased to the most at 12–24 hours, and decreased to normal at seven days after reperfusion. Conclusion: Ischemia-reperfusion injury is an important mechanism that results in pulmonary injury after liver transplantation. It is safe for portal hypertensive rats to tolerate 1 hour at the anhepatic phase. Pulmonary injury was the most severe within 12–24 hours after ischemia-reperfusion.     

Comparison of Protective Effects of Safflor Injection and Extract of Ginkgo Biloba on Lung Ischemia/Reperfusion Injury in Rabbits

Objective:To observe the protective effects of safflor Injection(SI) and extract of Ginkgo biloba(EGB) on lung ischemia-reperfusion injury(LIRI) and investigate its mechanism.Methods:In vivo rabbit model of LIRI was reconstructed.Forty rabbits were randomly and equally divided into four groups:sham-operation group(sham group),ischemia-reperfusion group(model group),ischemia-reperfusion plus SI group(safflor group) and ischemia-reperfusion plus EGB injection group(EGB group).Malondialdehyde(MDA) content,superoxide dismutase(SOD) and xanthine oxidase(XO) activity in serum were measured.The wet/dry weight ratio(W/D) of the lung tissue and activity of myeloperoxidase(MPO) were also tested.Ultrastructure change of the lung tissue was observed by the electron microscope.The expression of intercellular adhesion molecule-1(ICAM-1) was measured by immunohistochemistry(IHC).Results:In the model group,MDA and XO increased and SOD decreased in serum compared with the sham group(P<0.01).The values of W/D,MPO and ICAM-1 of the model group were higher than those of the sham group(P<0.01),but those of the safflor group and EGB group were significantly lower than those of the model group(P<0.01).The IHC demonstrated that ICAM-1 expression in lung tissue of the model group was significantly higher than those of the safflor group(P<0.01).Compared with safflor group,in the EGB group MDA,XO,MPO decreased,SOD and ICAM-1expression increased(P<0.05),but the change of W/D was not statistically significant(P>0.05).Conclusions:SI and EGB may attenuate LIRI through antioxidation,inhibition of neutrophil aggregation and down-regulation of ICAM-1expression.But EGB had more effect on the antioxidation,while SI did better on regulating ICAM-1 expression.     

加味丹参饮通过PTEN/PI3K/Akt信号通路抑制IRI作用的研究

目的:探讨加味丹参饮预处理通过抑瘤基因/磷脂酰肌醇-3激酶/蛋白激酶B(PTEN/PI3K/Akt)信号通路对大鼠心肌缺血再灌注损伤(IRI)的保护作用及机制。方法:将75只雄性远交群(SD)大鼠随机分为5组:假手术组、模型组、加味丹参饮组、加味丹参饮+PI3K/Akt通路抑制剂(LY294002)组、LY294002组,采用结扎大鼠冠状动脉左前降支30min后再灌注60min的方法制备IRI模型。采用酶联免疫吸附测定(ELISA)法检测各组大鼠心肌肌钙蛋白I(c Tn I)表达;取心肌梗死边缘区心肌组织,采用脱氧核糖核苷酸末端转移酶介导的缺口末端标记(TUNEL)法检测心肌凋亡指数,采用免疫组化法检测各组大鼠心肌组织Akt、PTEN的表达。结果:与假手术组比较,模型组c Tn I水平显著升高,大鼠心肌凋亡指数增加,PTEN、Akt表达均显著升高(P<0.05);与模型组比较,加味丹参饮组c Tn I水平均显著降低,Akt表达升高,心肌凋亡指数和PETN表达降低(P<0.05);与加味丹参饮组比较,加入抑制剂后,c Tn I水平均明显降低,Akt表达降低,PTEN表达升高(P<0.05)。结论:大鼠心肌缺血再灌注时,加味丹参饮可以通过降低PTEN表达,激活PI3K/Akt信号通路,抑制大鼠心肌细胞的凋亡,从而减轻心肌损伤,保护心肌。     

浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用

目的:探究浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用。方法:共15只SD大鼠随机分为心肌缺血-再灌注损伤合并脓毒症浅低温(MHT)组、心肌缺血-再灌注损伤合并脓毒症常温(NT)组和假手术常温组作为对照组。大鼠心肌缺血后再灌注同时给予内毒素,然后MHT组将大鼠置于冰床降温,15 min内达(33.0±0.5)℃,随后维持2 h。NT组及对照组实验全程维持在(37.0±0.5)℃。实验全程观察和记录血流动力学指标。浅低温或常温维持2 h后用酶联免疫吸附测定法检测血乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK-MB),观察心肌梗死面积、病理学变化,免疫印迹法检测心肌烟酰胺腺嘌呤二核苷酸磷酸氧化酶2(NOX2),免疫组化检测心肌胱天蛋白酶-3(caspase-3)和肿瘤坏死因子-α(TNF-α)。结果:MHT组再灌注2 h心率较NT组降低[(396.63±39.93)次/min vs(.457.74±32.77)次/min,P<0.05];左心室最大收缩压升高[(129.14±34.05)mmHg vs.(85.63±14.74)mmHg,1 mmHg=0.133 kPa,P<0.05]。MHT组收缩期压力最大变化速率(+max dp/dt)、左心室舒张末期压力(LVEDp)和舒张期压力最小变化速率(-min dp/dt)再灌注2 h较NT组绝对值也有所增加,且均高于对照组,但差异无统计学意义。MHT组的LDH和CK-MB均较NT组显著降低[(1153.61±127.85)U/L vs(.2213.34±599.60)U/L,P<0.05;(1103.22±114.75)U/L vs(.1731.33±688.05)U/L,P<0.05]。心肌病理变化提示MHT组心肌坏死呈点状或灶状,心肌间质淤血程度轻且炎细胞浸润较少。NT组心肌出现水肿、灶状或片状坏死,心肌间质区淤血程度重及存在大量炎细胞浸润。此外,MHT组的心肌梗死面积比率明显小于NT组[(11.23±2.82)%vs.(19.25±4.45)%,P<0.05]。免疫印迹法显示,NOX2在MHT组中相对表达量较NT组减少,但差异无统计学意义(P>0.05)。MHT组的caspase-3相对表达量及TNF-α相对表达量均较NT组显著降低[(1.06±0.34)%vs.(3.27±0.67)%;(12.23±3.31)%vs(.31.14±1.69)%],差异均有统计学意义(P均<0.05)。结论:浅低温对心肌缺血-再灌注损伤合并脓毒症有心脏保护作用,可改善心功能,减少心肌梗死面积,减轻心肌损伤、炎症、氧化应激及凋亡。     

基于PI3K/Akt通路探讨氯吡格雷对脑缺血再灌注损伤大鼠的神经保护作用

目的基于磷酯酰激醇3-激酶/蛋白激酶B(PI3K/Akt)通路探讨氯吡格雷对脑缺血再灌注损伤大鼠的神经保护作用.方法建立脑缺血再灌注大鼠模型,随机分为模型组、氯吡格雷组、LY294002(PI3K抑制剂)组、氯吡格雷+LY294002组,每组12只,另取12只SD大鼠设为假手术组.分组处理后,所有大鼠进行神经功能缺损评分并尾静脉取血,处死大鼠,HE染色检测各组大鼠神经元病理情况;三苯基氯化四氮唑(TTC)染色检测各组大鼠脑组织梗死面积;ELISA检测血清中中枢神经特异性蛋白(S100β)、神经元特异性烯醇化酶(NSE)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)水平;蛋白免疫印迹法检测脑组织中PI3K/Akt通路蛋白表达情况.结果与假手术组相比,模型组大鼠脑组织神经元出现坏死、核收缩变小等病理变化,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均明显升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt明显降低(P<0.05);与模型组相比,氯吡格雷组大鼠神经元病理损伤减轻,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均降低(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt升高(P<0.05);LY294002组大鼠神经元病理损伤加重,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt降低(P<0.05).与LY294002组相比,氯吡格雷+LY294002组大鼠神经元病理损伤减轻,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均降低(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt升高(P<0.05).与氯吡格雷组相比,氯吡格雷+LY294002组大鼠神经元病理损伤加重,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt降低(P<0.05).结论氯吡格雷可通过激活PI3K/Akt通路减轻大鼠脑缺血再灌注损伤,保护脑组织.