丝裂原活化蛋白激酶选择性抑制剂对葡聚糖硫酸钠结肠炎的影响

目的探讨p38丝裂原活化蛋白激酶（p38MAPK）选择性抑制剂SB203580对葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎的影响。方法24只雌性BALB／C小鼠均分为三组：正常对照组、DSS结肠炎组和SB203580干预组。结肠炎组小鼠每日自由摄取5％DSS溶液．干预组小鼠在摄取5％DSS溶液72h后，每日腹腔注射SB2035801mg／kg体质量。各组小鼠每日记录疾病活动指数（DAI）评分，H-E染色观察小鼠结肠黏膜组织学改变。ELISA法测定结肠组织巾肿瘤坏死因子（TNF）-a含量。免疫组化染色观察磷酸化的活化转录因子2（P-ATF2）在结肠组织炎性细胞内的表达情况。结果正常对照组和DSS结肠炎组小鼠的DAI评分为0．224-0．09和4．81±1．08（P〈0．05），组织学评分为1．03±0．38和11．0±0．75（P〈0．05），经SB203580干预后分别为1．96±0．89和7．16±1．46，与结肠炎组小鼠比较差异有统计学意义（P00．05）。正常对照组与DSS结肠炎组小鼠的结肠匀浆TNF-a含量分别为（42．98±17．31）和（128．34±33．76）pg／ml（P〈0．05），SB203580于预后下降为（81．86±25．11）pg／ml，与结肠炎组小鼠比较差异有统计学意义（P〈0．05）。正常对照组与结肠炎组小鼠结肠组织炎性细胞P-ATF2的表达分别为（6．91±1．83）％和（81．02±12．35）％（P〈0．05），经SB203580处理后为（38．59±8．12）％，与结肠炎组小鼠比较差异有统计学意义（P00．05）。结论阻断p38MAPK信号转导通路可明显缓解DSS诱导的结肠炎。预示此信号转导通路可为溃疡性结肠炎新药研究提供有价值的靶标。     

p38丝裂原活化蛋白激酶抑制剂减少大鼠肝脏炎症细胞因子的表达

目的 观察p38丝裂原活化蛋白激酶(MAPK)抑制剂SB203580阻断p36 MAPK信号通路,减少脑死亡大鼠肝脏促炎细胞因子表达的作用.方法 雄性Wistar大鼠30只,体质量180～200 g,随机分3组,每组10只.脑死亡组:诱导大鼠及死亡;脑死亡+SB203580组:大鼠脑死亡诱导成功后,经阴茎背静脉注射SB203580(10 mg/kg);两组大鼠脑死亡诱导成功,行人工呼吸6 h后,若平均动脉压大于80 mm Hg(1 mm Hg=0.133 kPa),则为脑死亡供体,获取肝脏待检.对照组:正常大鼠麻醉后取肝脏待检.逆转录-聚合酶链反应检测肝脏肿瘤坏死因子(TNF)α和白细胞介素(IL)-1β的mRNA表达,Western blot检测肝脏TNF α和IL-1 β的蛋白质表达以及磷酸化p38 MAPK的表达.多个样本间比较行One-Way ANOVA分析,SNK法行两两样本间比较.结果 脑死亡组大鼠肝脏出现p38 MAPK磷酸化,磷酸化p38 MAPK的相对表达量比对照组明显增加(0.190±0.004比0.001±0.002),差异有统计学意义(q=172.53,P＜0.01);肝脏TNF α的mRNA和蛋白质表达量分别为0.670±0.012和0.240±0.003,较对照组(分别为0.130±0.013和0.001±0.002)明显增加(q值分别为123.99和243.09,P值均＜0.01);肝脏IL-1 β的mRNA和蛋白质表达量分别为0.560±0.009和0.190±0.003,较对照组(分别为0.160±0.010和0.001±0.002)明显增加(q值分别为135.35和192.23,P值均＜0.01).脑死亡SB203580组大鼠肝脏p38 MAPK磷酸化下降,磷酸化p38 MAPK的表达量(0.120±0.004)比脑死亡组明显下降(q=63.90,P＜0.05),但仍明显高于对照组(q=108.63,P＜0.01);肝脏TNF α的mRNA和蛋白质表达量分别为0.430±0.016和0.180±0.004,较脑死亡组明显下降(q值分别为55.11和61.03,P值均＜0.01),但仍高于对照组(q值分别为68.89和182.06,P值均＜0.01);肝脏IL-1β的mRNA和蛋白质表达量分别为0.270±0.009和0.140±0.004,较脑死亡组明显下降(q值分别为98.13和50.85,P值均＜0.01),但仍高于对照组(q值分别为37.22和141.38,P值均＜0.01).结论 SB203580能抑制p38 MAPK的磷酸化,阻断p38 MAPK信号通路,减少脑死亡大鼠肝脏促炎细胞因子表达,降低肝脏免疫原性.     

p38信号通路在内皮细胞微粒诱导人脐静脉内皮细胞表达细胞间黏附分子-1中的作用

目的观察p38信号通路（P38MAPK）在内皮细胞微粒（EMPs）诱导人脐静脉内皮细胞（HU—VECs）表达细胞间黏附分子-1（ICAM-1）中的作用。方法将体外培养的HUVECs随机分组：①EMPs不同时点观察组：用EMPs（终浓度105／m1）分别刺激细胞0、3、6、12、24h;②EMPs不同剂量作用组：分别用终浓度为0、10^2、10^3、10^4、10^5／ml的EMPs刺激细胞24h;③EMPs＋p38MAPK特异性抑制剂SB203580组：在EMPs（终浓度10^5／ml）刺激前,与终浓度为5μmol／L的SB203580共同孵育30min。用蛋白免疫印迹法（Western blot）测定p38MAPK磷酸化表达,实时荧光定量PCR测定ICAM—1mRNA的表达。结果EMPs可激活p38MAPK,使磷酸化p38MAPK蛋白表达量及ICAM—1mRNA表达量增加,且呈剂量和时间依赖性。p38MAPK特异性拈抗剂SB203580可显著抑制EMPs的此作用。结论p38信号通路可能部分参与了对EMPs诱导HUVECs表达ICAM-1的调控。     

p38MAPK对大鼠肾小球系膜细胞表达COX-2的影响

目的 探讨p38丝裂原活化蛋白激酶（p38MAPK）和环氧化酶2（COX-2）的关系,从而研究p38MAPK和COX-2在糖尿病肾病（DN）中的作用机制.方法 分别以高葡萄糖、高胰岛素、过氧化氢和糖基化终产物孵育大鼠肾小球系膜细胞系HBZY-1;先以p38MAPK特异抑制剂SB203580预处理细胞系HBZY-1,再给予上述4种因素孵育细胞系HBZY-1,观察细胞系HBZY-1 p38MAPK和COX-2的表达.结果 高葡萄糖、高胰岛素、过氧化氢和糖基化终产物均可独立激活p38MAPK,使其磷酸化表达量增加,COX-2表达也明显增加;SB203580预处理后,COX-2表达被显著抑制.结论 p38MAPK调控COX-2的表达,表明p38MAPK是COX-2的上游激酶之一,p38MAPK和COX-2可能在DN的发生发展过程中起重要作用.     

p38 MAPK信号转导通路参与NO诱导兔关节软骨细胞凋亡

目的探讨p38 MAPK信号转导通路在软骨细胞凋亡中的作用。方法体外培养兔关节软骨细胞,一氧化氮(NO)供体NOC-18和p38 MAPK抑制剂SB203580作用于细胞24 h,用AnnexinV-FITC/PI流式细胞术检测软骨细胞凋亡率,W estern b lot测定p38、磷酸化p38蛋白的表达水平。结果与对照组比较,SB203580显著降低了NOC-18诱导的软骨细胞凋亡率(P<0.05);NOC-18以浓度依赖的方式促进p38 MAPK的磷酸化,而SB203580能抑制其磷酸化(P<0.05)。结论p38 MAPK通路参与了NO诱导的兔关节软骨细胞凋亡的信号转导。     

AGEs刺激对小鼠肝脏moesin表达及其磷酸化水平的影响

目的探讨糖基化蛋白终产物（AGEs）刺激对小鼠肝脏膜突蛋白（moesin）表达及其磷酸化水平的影响。方法 24只C57 BL/6雌性小鼠,随机分为对照组、AGE组、SB203580＋AGE组和Y27632＋AGE组,各6只。制备模型后,取小鼠肝脏组织进行石蜡包埋、切片,通过免疫组化法对各组肝脏moesin及其磷酸化moesin进行观察并行半定量分析。结果四组moesin均主要表达在肝窦和微血管的内皮细胞,肝细胞或胆管上皮细胞无表达;对照组磷酸化moesin几乎观察不到;AGE组肝窦和微血管内皮细胞中558位苏氨酸磷酸化moesin的表达明显增加;SB203580＋AGE组和Y27632＋AGE组肝脏内皮细胞磷酸化moesin染色深度明显低于AGE组并高于对照组。对照组、AGE组、SB203580＋AGE组、Y27632＋AGE组moesin灰度值分别为84.7±0.35、86.2±0.57、85.5±0.69、84.9±0.67,各组moesin相比,P均〉0.05;其磷酸化moesin灰度值分别为34.6±0.36、82.2±0.92、35.7±0.51、35.9±1.67;AGE组的磷酸化moesin与其余三组相比,P均〈0.05。结论 moesin在肝脏主要表达在肝窦和微血管的内皮细胞,AGEs处理或抑制p38 MAPK、ROCK活性后再给予AGEs均不影响肝脏moesin蛋白的表达;AGEs可导致肝脏内皮细胞moesin磷酸化,p38 MAPK和ROCK两条信号途径参与了moesin磷酸化的过程。     

硫化氢在p38MAPK信号通路对大鼠肝星状细胞凋亡中的作用

目的探讨硫化氢(H2S)在p38MAPK信号通路对大鼠肝星状细胞(hepatic stellate cell,HSC)凋亡中的作用及磷酸化P38、Caspase-3蛋白表达的变化。方法实验设对照组(HSC加含10%胎牛血清的DMEM培养液)、二甲基亚砜(DMSO)组(对照组基础上加DMSO,使其终浓度为0.1%)、NaHS组(对照组基础上加NaHS,使其终浓度为50μmol/L)、SB组(DMSO组基础上加SB203580,使其终浓度为75μmol/L)、SB加NaHS(SB+NaHS)组;采用Hoechst荧光染色检测细胞凋亡;Western blotting法检测磷酸化p38MAPK表达及Caspase-3蛋白表达水平。结果与对照组比较,SB组和SB+NaHS组HSC-T6的凋亡率增加(P0.05),NaHS组p38MAPK磷酸化水平及Caspase-3表达均明显增高(P0.01);与NaHS组比较,SB组和SB+NaHS组细胞凋亡率增加明显(P0.01),p38MAPK磷酸化水平表达降低(P0.01);SB+NaHS组较SB组Caspase-3蛋白表达升高(P0.05)。结论 p38MAPK及Caspase-3在H2S刺激的HSC-T6中表达增强,H2S能促使SB203580诱导的HSC-T6细胞凋亡,其作用机制可能与活化p38MAPK的磷酸化途径,进而激活Caspase-3的表达有关。     

阿托伐他汀抑制同型半胱氨酸诱导的内皮细胞凋亡涉及NADPH氧化酶及p38MAPK途径

目的观察阿托伐他汀对同型半胱氨酸（Hcy）诱导的人脐静脉内皮细胞凋亡及活性氧的影响,并探讨其作用机制。方法Hcy单独或联合阿托伐他汀、N-乙酰半胱氨酸（NAC）、还原型辅酶Ⅱ（NADPH）氧化酶抑制剂（DPI）或p38促细胞分裂剂激活性蛋白激酶（p38MAPK）阻断剂（SB203580）处理人脐静脉内皮细胞后,检测细胞凋亡率,活性氧水平,NADPH氧化酶活性,caspase-3 mRNA的表达和p-p38MAPK的表达。结果阿托伐他汀明显抑制Hcy诱导的人脐静脉内皮细胞凋亡及活性氧的产生,并能拮抗Hcy诱导的NADPH氧化酶的激活,p38MAPK蛋白的磷酸化及caspase-3 mRNA表达的增加。NAC、DPI、SB203580可产生相同的作用。结论阿托伐他汀可能通过抑制NADPH氧化酶的激活,p38MAPK磷酸化途径抑制Hcy诱导的人脐静脉内皮细胞活性氧的产生和细胞凋亡。     

MR弥散加权成像在鉴别前列腺良恶性组织中的价值

目的研究前列腺良恶性病灶的磁共振表观弥散系数（apparent diffusion coefficienl，ADC）的差异。方法对健康对照27例、前列腺癌（PCa）患者25例行MR弥散加权成像（diffusion weighted imaging，DWI）。按B超引导穿刺活检操作医师在前列腺样图中标出的相应位置选出感兴趣区域（regions of interest，ROI），分别对癌灶和正常前列腺组织的ADC值进行测定，比较其差异是否存在统计学意义。结果健康对照组的ADC平均值（1．73±0．16）×10^-3 mm^2／s；最低值（1．30±0．15）×10^-3mm^2/s；PCa组ADC平均值（0．81±0．12）×10^-3mm^2／s；最低值（0．58±0．10）×10^-3mm^2/s，分别通过t检验（P〈0．001），两组间差异均存在统计学意义。结论ADC值能定量地反映前列腺组织信息，PCa病灶的ADC值明显低于正常组织。ADC值是鉴别前列腺良恶性病灶一个很有价值的可定量参数。     

反义真核细胞转化生长因子βⅠ型受体与反义基质金属蛋白酶组织抑制因子-1联合作用对大鼠肝纤维化的影响

目的观察反义转化生长因子βⅠ型受体（TβRI真核表达质粒与反义基质金属蛋白酶组织抑制因子-1（TIMP-1）真核表达质粒联合作用对实验性大鼠肝纤维化的影响。方法构建大鼠反义真核细胞表达质粒，导入大鼠肝纤维化模型体内，通过I型胶原的免疫组织化学以及苦味酸-酸性品红染色观察两种反义质粒联合作用对大鼠肝纤维化的影响，用目标积分吸光度（A）值表示各实验组动物肝组织中蛋白的表达量。结果反义TβRI疗组、反义TβRI反义TIMP-1治疗组、反义TIMP-1治疗组、pcDNA3．1（＋）空质粒对照组、模型对照组、正常对照组TβRI白的A值分别为：（2．11±0．88）×10^5、（1．06±0．57）×10^5、（3．46±1．14）×10^5、（5．66±2．54）×10^5、（5．19±1．22）×10^5和（0．38±0．27）×10^5；TIMP-1蛋白的A值分别为：（1．10±0．22）×10^5、（0．30±0．12）×10^5、（0．65±0．15）×10^5、（2．05±0．36）×10^5、（1．97±0．28）×10^5和（0．10±0．12）×10^5；I型胶原的蛋白表达的A值分别为：（4．37±1．30）×10，、（0．90±0．32）×10^5、（3．40±0．91）×10^5、（6．90±1．61）×10^5、（7．34±1．68）×10^5和（0．41±0．21）×10s。反义TIMP-1治疗组TIMP-1蛋白表达量显著降低（P〈0．05），反义TβRI疗组TβRI白表达量显著降低（P〈0．05），两种反义质粒可有效抑制相应蛋白的表达；反义TIMP-1表达质粒与反义TβRI达质粒均可减少受损肝脏中I型胶原的沉积（P〈0．05），联合应用可进一步减少受损肝脏中I型胶原的沉积（P〈0．01）。在病理形态学方面的观察，反义TIMP-1表达质粒与反义TβRI达质粒均可使受损肝脏的病理形态有一定改善，联合应用可使受损肝脏的病理形态得到进一步的改善。结论反义TIMP-1表达质粒与反义TβRI达质粒对肝纤维化的发展均有一定的干预作用，联合作用可产生更有效的阻止作用。     

Kinase activity, heat shock protein 27 phosphorylation, and lung epithelial cell glutathione

The 27-kDa heat shock protein (Hps27) is phosphorylated in a way that appears to regulate antioxidant defenses by mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), a component of the p38(MAPK) pathway. To investigate the role of Hsp27 in cellular resistance to oxidant stress, lung cells (A549) were incubated with MAPK inhibitors to investigate the pathway's role in antioxidant defense. Cells were harvested for measurement of reduced gluthathione and glutathione disulfide (GSH and GSSH); or, exposed to 2,3-dimethoxy-1,4-napthoquinone (DMNQ). Inhibition of MAPK with SB203580 decreased total cellular glutathione (mean +/- SE): Vehicle, 150 +/- 20 mu M; SB203580, 57 +/- 10* (*P < .01). Inhibition of MAPK tripled [GSSG]/[GSH]: Vehicle, 0.29 +/- 0.09; SB203580, 1.06 +/- 0.43* (*P > .05; n = 6 per group). Hsp27 protein content did not change significantly after MAPK inhibition: Vehicle 2.20 +/- 0.24 ng/mg protein; SB203580, 2.03 +/- 0.34 (P > .05). Transfection of epithelial cells with wild-type (pcDNA-HA-Hsp27) or phosphomimic (pcDNA-HA-Hsp27-S3D) vector increased Hsp27 protein, which significantly protected cells from oxidant stress. Inhibition of the MAPK system, including p38(MAPK), results in cellular oxidant stress. Hsp27, which is phosphorylated by MK2 in the MAPK pathway, protects epithelial cells from oxidant stress.     

Role of phasic dynamism of p38 mitogen-activated protein kinase activation in ischemic preconditioning of the canine heart

Although ischemic stress, including ischemic preconditioning (IP), activates p38 mitogen-activated protein kinase (MAPK), the relationship between p38 MAPK activation and the underlying cellular mechanisms of cardioprotection by IP is not verified in vivo. We examined the effects of the selective p38 MAPK inhibition on the cardioprotective effect of IP in the open-chest dogs. The coronary artery was occluded 4 times for 5 minutes, separated by 5 minutes of reperfusion (IP) followed by 90 minutes of occlusion and 6 hours of reperfusion. We infused SB203580 into the coronary artery during IP and 1 hour of reperfusion, during IP alone, and during sustained ischemia in the IP group. p38 MAPK activity markedly increased during IP but did not additionally increase at the onset of ischemia and was even attenuated at 15 minutes of sustained ischemia, and heat-shock protein (HSP) 27 was phosphorylated and translocated from cytosol to myofibril or nucleus without affecting total protein level at the onset of ischemia compared with the control group. SB203580 treatment (1 micromol/L) only during IP blunted the infarct size limitation by IP (37.3+/-6.3% versus 7.4+/-2.1% in the IP group, P:<0.01) and attenuated either phosphorylation or translocation of HSP27 during IP. Although the SB203580 treatment throughout the preischemic and postischemic periods had no significant effect on infarct size (33.3+/-9.4%) in this model, treatment with SB203580 only during ischemia partially mimicked the infarct size limitation by IP (26.8+/-3.5%). Thus, transient p38 MAPK activation during ischemic preconditioning mainly mediates the cardioprotection followed by HSP27 phosphorylation and translocation in vivo in the canine heart.     

Inhibition of p38 mitogen-activated protein kinase decreases cardiomyocyte apoptosis and improves cardiac function after myocardial ischemia and reperfusion

BACKGROUND: Activation of p38 mitogen-activated protein kinase (MAPK) plays an important role in apoptotic cell death. The role of p38 MAPK in myocardial injury caused by ischemia/reperfusion, an extreme stress to the heart, is unknown. METHODS AND RESULTS: Studies were performed with isolated, Langendorff-perfused rabbit hearts. Ischemia alone caused a moderate but transient increase in p38 MAPK activity (3.5-fold increase, P<0.05 versus basal). Ischemia followed by reperfusion further activated p38 MAPK, and the maximal level of activation (6.3-fold, P<0.01) was reached 10 minutes after reperfusion. Administration of SB 203580, a p38 MAPK inhibitor, decreased myocardial apoptosis (14.7+/-3.2% versus 30.6+/-3.5% in vehicle, P<0.01) and improved postischemic cardiac function. The cardioprotective effects of SB 203580 were closely related to its inhibition of p38 MAPK. Administering SB 203580 before ischemia and during reperfusion completely inhibited p38 MAPK activation and exerted the most cardioprotective effects. In contrast, administering SB 203580 10 minutes after reperfusion (a time point when maximal MAPK activation had already been achieved) failed to convey significant cardioprotection. Moreover, inhibition of p38 MAPK attenuated myocardial necrosis after a prolonged reperfusion. CONCLUSIONS: These results demonstrate that p38 MAPK plays a pivotal role in the signal transduction pathway mediating postischemic myocardial apoptosis and that inhibiting p38 MAPK may attenuate reperfusion injury.     

特异性p38蛋白激酶抑制剂SB203580对小鼠感染肺炎衣原体后细胞因子变化的影响

目的 探讨特异性p38蛋白激酶(p38 MAPK)抑制剂SB203580对小鼠感染肺炎衣原体后细胞因子变化.方法 使用TLR4基因缺失(C3H/HeJ)小鼠90只,随机分为正常组、感染组和SB203580组,每组再分别按0、1、4、7、14 d分成5小组.正常组鼻内接种二磷酸蔗糖缓冲液,感染组鼻内接种肺炎衣原体约4.0×106 IFU/ml,SB203580组在感染肺炎衣原体后腹腔注射SB203580(100 mg/kg).分别在接种后第0天,第1天、第4天、第7天、第14天预定的时间处死小鼠,取肺组织分别采用Western blot法测p38 MAPK蛋白的表达,用酶联免疫吸附法检测肺组织中肿瘤坏死因子α(TNF-α)、白介素1(IL-1)的表达,同时观察各组小鼠肺组织病理变化.结果 感染组肺组织中TNF-α、IL-1的表达水平在各时间点均高于正常组(P＜0.05或P＜0.01),并在第4天出现高峰,14天以后开始下降.SB203580组肺组织中细胞因子TNF-α、IL-1的表达水平在各时间点均低于感染组(P＜0.05或P＜0.01).同时,SB203580组p38 MAPK蛋白表达强度弱于感染组.结论 p38 MAPK参与小鼠感染肺炎衣原体的炎症反应,特异性p38 MAPK抑制剂SB203580能抑制小鼠感染肺炎衣原体后的细胞因子表达,减轻炎症反应.     

p42/44MAPK regulates baseline permeability and cGMP-induced hyperpermeability in endothelial cells

We tested the hypothesis that p42/44MAPK and p38MAPK (mitogen-activated protein kinases; MAPK) signaling pathways regulate endothelial cell permeability to macromolecules. Passage 2-4 human umbilical vein endothelial cells (HUVEC) were grown to confluence on fibronectin-coated Snapwell membranes. The flux of fluorescein isothiocyanate-labeled dextran-70 across the HUVEC monolayers served to determine permeability. Application of 1 mM 8-bromo 3' 5'-cyclic guanosine monophosphate (8-Br-cGMP) increased permeability from 7.0 +/- 1.6 x 10(-6) to 12.5 +/- 2.8 x 10(-6) cm/s (P < 0.05). Pretreatment of HUVEC for 60 min with a selective p42/44MAPK inhibitor (AG126 at 2.7 and 27 microM) blocked 8-Br-cGMP-induced hyperpermeability. However, inhibition of p38MAPK (SB203580 at 0.6 microM) did not influence the cGMP-induced hyperpermeability response. AG126, administered at 27 microM, decreased baseline permeability from 7.9 +/- 0.5 x 10(-6) to 5.9 +/- 0.5 x 10(-6) cm/s (P < 0.05). Our results indicate that the p42/44MAPK signaling pathway is important in the regulation of baseline permeability and cGMP-induced hyperpermeability.     

p38 MAP kinase is a mediator of ischemic preconditioning in pigs

OBJECTIVE: The role of p38MAPK in ischemic preconditioning (IP) is still equivocal, insofar as the p38MAPK-inhibitor SB203580 abolished IP in rats, rabbits and dogs, but not in pigs. Blockade of p38MAPK prior to the sustained ischemia also generated contradictory findings, insofar as p38MAPK acted as trigger in dogs but as mediator in rats. We have now tested whether the two structurally unrelated p38MAPK-inhibitors, BIX-645 and SB203580, abolished infarct size (IS) reduction by IP in pigs and whether their effects depended on the time of administration. METHODS: Sixty-five enflurane-anesthetized pigs underwent 90 min low-flow ischemia and 120 min reperfusion without or with one preceding cycle of 10 min preconditioning ischemia and 15 min reperfusion. Pigs received BIX-645 (1 mg/kg, i.v.) or SB203580 (10 microM, i.c.) prior to either IP or the sustained ischemia. RESULTS: IS (% TTC-staining) was reduced by IP [4.8+/-3.1(S.E.M.), P<0.05] compared to placebo (25.8+/-5.5). BIX-645 or SB203580 per se had no effect on IS (23.5+/-5.2 and 21.8+/-4.4, respectively). IS reduction by IP was abolished by BIX-645 (26.2+/-6.4 or 25.5+/-4.7) and SB203580 (19.9+/-4.3 or 16.7+/-4.7), given either prior to IP or the sustained ischemia, respectively. The supernatant of homogenized myocardial biopsies taken during the sustained ischemia from preconditioned pigs receiving either BIX-645 or SB203580 inhibited the anisomycin-stimulated ATF-2 phosphorylation in cultured Rat1 fibroblasts. This in vitro inhibition of ATF-2 phosphorylation correlated to the actual IS. CONCLUSION: The attenuation of the IS-reducing effect of IP depends on the effectiveness of blockade of p38MAPK activity. p38MAPK is a mediator of IP in pigs.     

Coronary microembolization induced myocardial contractile dysfunction through a p38 mapk pathway

Background Cathepsin S and its endogenous inhibitor cystatin C are implicated in the pathogenesis of atherosclerosis,especially in the plaque destabilization and rupture leading to acute coronary syndrome.However, whether circulating cathepsin S and cystatin C also change in association with coronary plaque morphology is unknown yet. Methods Sprague-Dawley rats were randomly divided into three groups;Sham group,CME group and SB203580 group (n=10 per group).CME rats were produced by injection of 42μm microspheres into the left ventricle with occlusion of the ascending aorta.SB203580,a p38 MAPK inhibitor,was injected into femoral vein after finishing the injection of microspheres in SB203580 group.Left ventricular Ejection Fraction was determined by echocardiography.The level of phosphorylated and total P38 MAPK in myocardium was assessed by Western Blot.Results Left ventricular(LV) Ejection Fraction was depressed at 3 hours and until up to 12 hours in CME group.The increased p38 MAPK activation was observed in CME group.The administration of SB203580 partly inhibited the p38 MAPK activity and preserved cardiac contractile function.Conclusions p38 MAPK is significantly activated by CME and the inhibition of p38 MAPK can partly preserve cardiac contractile function.     

Inhibition of p38 MAPK activity fails to attenuate contractile dysfunction in a mouse model of low-flow ischemia

OBJECTIVE: The basal activity of p38 MAPK has recently been shown to impair myocardial contractility. This kinase is activated by ischemia and short-term hibernation. We hypothesized that p38 MAPK activation may contribute to the contractile deficit that characterizes low-flow ischemia. METHODS: In Langendorff-perfused isolated C57BL/6 mouse hearts, perfusion pressure was reduced from 85 to 15 or 30 mm Hg for 120 min to induce ischemic left ventricular dysfunction. The effect of the p38 MAPK inhibitor SB203580 (1 microM/l) on contractile function and p38 MAPK activation was assessed. RESULTS: Reduction in perfusion pressure to 15 or 30 mm Hg was accompanied by stable reductions in coronary flow (83+/-2% and 66+/-2%, respectively) and developed pressure (84+/-2% and 61+/-3%), with minimal infarction (15.6+/-0.69% and 10.6+/-0.98% of LV myocardium, respectively), but marked activation of p38 MAPK (reflected in pHSP27 1092+/-326% basal and 996+/-301% basal, respectively). The p38 MAPK inhibitor SB203580, present during the last 60 min of reduced pressure perfusion, prevented p38 MAPK activation (pHSP27 281+/-92% basal, p=0.01 and 186+/-72% basal, p=0.01) but, despite the presence of a contractile reserve, had no effect on developed pressure. Similarly, early treatment with SB203580 started 5 min after the onset of reduced flow also failed to attenuate contractile dysfunction. CONCLUSION: The p38 MAPK activation that accompanies short-term hibernation does not appear to contribute to the contractile deficit.