苦参素对H2O2诱导乳鼠心肌细胞氧化应激损伤保护作用的研究

目的 研究苦参素（oxymatrine,OMT）对H₂O₂诱导乳鼠心肌细胞氧化应激损伤的保护作用。方法 无菌环境下分离并培养乳鼠心肌细胞72h后随机分为空白对照组、H₂O₂（200μmol/L）干预组、OMT（20、40、60μmol/L）+H₂O₂（200μmol/L）干预组,每组设10个复孔。药物干预12h后,MTT法检测细胞存活率,采用氧敏感荧光探针DCFH-DA检测氧自由基（ROS）;测定细胞中抗氧化酶（SOD、GSH-Px、CAT）活性和丙二醛（MDA）含量,检测细胞培养液中心肌酶（AST、CPK、LDH）含量,流式细胞术（flow cytometry,FCM）检测细胞凋亡并计算凋亡率,Western blot法检测细胞中caspase-3、NF-κB蛋白表达并进行半定量分析。结果 与H₂O₂（200μmol/L）干预组比较,OMT（40、60μmol/L）干预12h能够显著提高H₂O₂诱导损伤乳鼠心肌细胞存活率,降低ROS含量,改善SOD、GSH-Px、CAT活性并降低MDA含量,降低培养基中AST、CPK、LDH含量,降低细胞凋亡率,降低caspase-3、NF-κB蛋白表达,差异均有统计学意义（P<0.05,P<0.01）。结论 苦参素可能通过改善抗氧化酶活性而提高氧自由基清除能力、抑制促凋亡蛋白表达而降低细胞凋亡,对H₂O₂诱导乳鼠心肌细胞氧化应激损伤起到保护作用。     

风湿性心脏病心肌细胞内肌浆网钙离子转运功能变化的机制

目的：探讨风湿性心脏病（风心病）慢性心力衰竭时心肌细胞内肌浆网Ca2 转运功能变化的机制。方法：采用Westernblot法测定19例风心病患者（风心病组）和6例意外脑死亡者（对照组）心肌肌浆网钙泵蛋白和兰尼碱受体含量,同时采用草酸盐易化的肌浆网Ca2 摄取法测定两组心肌肌浆网的Ca2 摄取功能,采用测定“裸露”心肌束的咖啡因敏感性方法测定风心病患者心肌肌浆网的Ca2 释放功能。结果：风心病组钙泵蛋白和兰尼碱受体相对含量比对照组分别显著减少23％（P＜0．01）和10％（P＜0．05）,心肌匀浆肌浆网Ca2 摄取量和摄取率也均显著低于对照组（P＜0．05～P＜0．01）,并且风心病患者钙泵蛋白相对含量变化与肌浆网Ca2 摄取率变化呈显著正相关（r=0．81,P＜0．01）,“裸露”心肌束的相对Ca2 释放速率变化也明显低于正常水平,且与兰尼碱受体相对含量变化密切相关（r=0．67,P＜0．05）。结论：风心病心肌细胞内肌浆网Ca2 摄取和释放功能下降的机制主要与肌浆网的Ca2 摄取和释放蛋白含量变化有关。     

Antisense oligodeoxynucleotides of sulfonylurea receptors inhibit ATP-sensitive K+ channels in cultured neonatal rat ventricular cells

 To identify the functional sulfonylurea receptor (SUR), a subunit of the adenosine 5′-triphosphate (ATP)-sensitive K⁺ (K_ATP) channels, in neonatal rat ventricular cells, such cells in primary culture were treated for 6 days with antisense (AS) oligodeoxynucleotides (ODNs) complementary to the mRNA for SURs. For quantification, single-channel (inside-out patches) and whole-cell currents were measured using the patch-clamp technique. The maximal K_ATP currents (at 0 mV) induced by metabolic inhibition were 48.9±2.8 pA/pF in control (n=48), 34.3±3.5 pA/pF in AS-SUR1 (n=21, P<0.05 vs control), and 23.5±3.4 pA/pF in AS-SUR2 (n=17, P<0.01 vs control). As a control, scramble oligonucleotides had no effect. The fast Na⁺ current and inward-rectifying K⁺ current were not affected by AS-SURs. Treatment with both AS-SUR1 and AS-SUR2 had no additive effects on inhibition of K_ATP currents compared with AS-SUR2 alone. The single-channel conductance, open probability, and kinetics (in ATP-free solution) were not significantly different between control, AS-SUR1, and AS-SUR2. These results suggest that treatment with AS-ODN for SUR1 or SUR2 reduced the number of functional K_ATP channels. Furthermore, in four out of seven control cells tested, outward K⁺ currents were stimulated by diazoxide, which is a potent K⁺ channel-opening drug for the constructed SUR1/Kir6.2 and SUR2B/Kir6.2 channels, but not for the SUR2A/Kir6.2 channel. Therefore, in neonatal rat ventricular cells, both SUR2 and SUR1 subtypes could be integral components of the functional K_ATP channels. The larger population of K_ATP channels may be constructed with SUR2, whereas a smaller population may be constructed with a combination of SUR1 and SUR2. Received: 29 May 1998 / Received after revision: 8 September 1998 / Accepted: 13 October 1998     

卡托普利对外源性羟自由基诱导心肌细胞凋亡的影响

目的观察卡托普利对由外源性羟自由基诱导的心肌细胞凋亡有无影响。方法①利用第４代心肌细胞,随机分１５组,在终浓度为１０＾－５ｍｏｌ／Ｌ、１０＾－４ｍｏｌ／Ｌ、１０＾－３ｍｏｌ／Ｌ、１０＾－２ｍｏｌ／Ｌ、１０＾－１ｍｏｌ／Ｌ的羟自由基无血清条件培养下分别共孵育８ｈ、１６ｈ、２４ｈ,确定１０＾－３ｍｏｌ／Ｌ及２４ｈ为诱导心肌细胞凋亡的最佳浓度及时间。②在上述条件下分别观察３种不同浓度卡托普利（１０＾－７     

MAPK相互作用蛋白激酶1对心肌细胞炎症的作用

目的 于在体水平和离体水平研究MAPK相互作用蛋白激酶1对心肌细胞炎症的作用。方法 应用MAPK相互作用蛋白激酶1基因敲除小鼠和C57 BL/6野生型小鼠,行主动脉缩窄术,于术后4周取材。应用免疫荧光染色,检测心肌组织中P-NF-κBp65在心肌细胞中的核转位。应用Western blot法检测心肌组织中P-NF-κBp65和TNF-α。应用Mnk1 shRNA腺病毒转染技术,降低H9c2细胞中Mnk1的表达,给予血管紧张素Ⅱ刺激48h。应用免疫荧光染色,检测H9c2细胞中P-NF-κBp65的核转位。应用RT-PCR检测H9c2细胞中TNF-α mRNA的表达。结果 在体实验表明,主动脉缩窄术后4周,与野生型小鼠相比,MAPK相互作用蛋白激酶1基因敲除小鼠心肌组织中P-NF-κBp65在心肌细胞中的核转位明显增多,TNF-α和P-NF-κBp65的蛋白表达明显增加。离体实验表明,MAPK相互作用蛋白激酶1表达降低的H9c2细胞中P-NF-κBp65的核转位明显增多,TNF-α mRNA的表达明显增加。结论 MAPK相互作用蛋白激酶1基因缺失促进压力负荷诱导的小鼠心肌组织炎症,其表达降低可促进血管紧张素Ⅱ诱导的心肌细胞炎症。     

卡托普利对缺氧/复氧乳鼠心室肌细胞游离钙的影响及其离子通道机制

目的：观察卡托普利晚期预处理对缺氧/复氧乳鼠心室肌细胞游离钙的影响及其离子通道机制。方法:建立培养乳鼠心肌细胞缺氧/复氧损伤模型。设正常对照组、缺氧/复氧组、缺氧预适应组和卡托普利组。经Flou-3/AM负载染色后，采用流式细胞分析技术，测定细胞内钙离子浓度(［Ca²⁺］i)；利用膜片钳技术，观察L-型钙通道和钠钙交换电流的变化。结果:（1）缺氧/复氧时，［Ca²⁺］i和Na⁺/Ca²⁺交换电流高于正常对照组（P<0.01），L-型钙电流（I_Ca-L）峰值下降，I-V曲线上移，半数失活电压(V_0.5)减小，ICa-L失活曲线左移。（2）晚期预处理和卡托普利使缺氧/复氧时［Ca²⁺］i低于缺氧/复氧组（P<0.01）；I_Ca-L增加，I-V曲线下移，V_0.5增大及稳态失活曲线右移；Na⁺/Ca²⁺ 交换电流减少；但［Ca²⁺］i和Na⁺/Ca²⁺交换电流高于对照组（P<0.05）。（3）卡托普利组与缺氧预适应组比较上述指标均无显著差异 。结论：心肌细胞缺氧/复氧，通过Na⁺/Ca²⁺交换电流的异常增加可引起［Ca²⁺］i的异常升高及其钙超载；卡托普利通过轻度增加Na⁺/Ca²⁺交换电流及其［Ca²⁺］i而触发晚期预处理，抑制后续缺氧/复氧引起的Na⁺/Ca²⁺交换电流及其［Ca²⁺］i的异常增加。     

苦豆碱对缺血再灌注引起的H9c2心肌细胞损伤和炎症应答的作用

目的:明确苦豆碱对缺血再灌注(I/R)引起的大鼠心肌H9c2细胞损伤和炎症应答的作用及其机制。方法:采用缺氧/复氧的方法体外模拟缺血再灌注(SI/R)心肌损伤,用不同浓度苦豆碱处理,MTT实验分析苦豆碱对H9c2细胞存活率的影响;流式细胞术检测细胞凋亡;试剂盒检测乳酸脱氢酶(LDH)和丙二醛(MDA)的水平及caspase-3的活性;ELISA分析多种炎性因子水平;同时用Western blot法分析苦豆碱对PI3K/AKT信号通路的影响。结果:苦豆碱可对抗SI/R抑制的H9c2细胞存活率,同时明显降低SI/R引起的LDH及MDA浓度的增加(P0.05)。此外,苦豆碱能够显著抑制SI/R触发的细胞凋亡(P0.05),同时降低SI/R处理后引起的caspase-3活性的增加,并上调Bcl-2/Bax比值(P0.05)。与SI/R组相比,苦豆碱处理可显著性降低H9c2心肌细胞炎性因子白细胞介素6、肿瘤坏死因子α和白细胞介素1β的浓度(P0.05)。此外,与SI/R组相比,苦豆碱处理后可显著增加p-PI3K和p-AKT的蛋白水平(P0.05);当用LY294002抑制PI3K/AKT通路后,苦豆碱促心肌细胞存活、抗凋亡及抗炎症的作用明显减弱(P0.05)。结论:苦豆碱可通过激活PI3K/AKT信号通路对抗心肌细胞缺血再灌注引起的损伤及炎症应答,提示其对心肌缺血再灌注损伤的防治具有潜在应用价值。     

Protective effects of novel single compound, Hirsutine on hypoxic neonatal rat cardiomyocytes

Uncaria rhynchophylla is a traditional Chinese herb that has been applied in China for treatment of ailments of the cardiovascular system, but little is known about its active constituents and effect in cardiomyocytes. In present study, we investigated the cardioprotective effect of 0.1 μΜ, 1 μΜ and 10 μΜ Hirsutine isolated from the methanolic extracts of Uncaria rhynchophylla by high performance liquid chromatography (HPLC) on neonatal rat cardiomyocytes treated with hypoxia to determine the mechanism underlying the protective effect with regard to cardiac anti-oxidant enzymes and apoptosis genes. Hirsutine significantly increased the viability of cardiomyocytes injured by hypoxia. Gene expression levels of proapoptotic genes (Bax, Fas and caspase-3) were significantly downregulated compared with the hypoxic control group (P < 0.05), whereas the expression level of Bcl-2 was upregulated following Hirsutine treatment (P < 0.05). Correspondingly, Hirsutine treatment increased Bcl-2 protein level and decreased Bax protein level. Assay investigating cardiac anti-oxidant enzymes provided further evidence for the protective effect of Hirsutine, as indicated by the induction of the anti-oxidant enzymes superoxide dismutase. The results of present study suggest that the mechanism of action of Hirsutine in hypoxic neonatal rat cardiomyocytes may be related to its anti-oxidant and anti-apoptotic properties. This may open an avenue for developing novel candidate compounds with cardioprotective effect from unique Chinese plant.     

Hypoxia exacerbates Ca-handling disturbances induced by very low density lipoproteins (VLDL) in neonatal rat cardiomyocytes

It is known that myocardium suffers serious alterations under ischemic conditions such as lipid overloading and electrophysiological alterations. However, it is unknown whether intracellular lipid accumulation and calcium dysfunction share common pathophysiological mechanisms under ischemia. The aims of this study were 1) to analyze the effect of normal and high doses of very low density lipoproteins (VLDL) on lipid content and calcium handling; 2) to investigate whether hypoxia modulates the effect of high VLDL doses; and 3) to identify potentially underlying mechanisms in cardiomyocytes. For this purpose, neonatal rat ventricular myocytes cultures were prepared from hearts of 3-4-day-old rats. High doses of VLDL that induced cholesteryl ester (CE) and triglyceride (TG) accumulation strongly reduced sarco(endo)plasmic reticulum Ca ATPase-2 (SERCA-2) expression, calcium transient amplitude and sarcoplasmic reticulum (SR) calcium loading. Interestingly, hypoxia, by upregulating VLDL-receptor expression (4.5-fold at 16 h) increased CE (1.5-fold) and TG (3-fold) cardiomyocyte content and exacerbated the negative effect of VLDL on SERCA-2 expression. Functionally, the hypoxic exacerbation of VLDL-mediated SERCA-2 downregulation was translated into a stronger decrease in calcium transient amplitude and SR calcium loading in myocytes exposed simultaneously to hypoxia and high VLDL. In conclusion, high VLDL doses alter calcium handling in cardiomyocytes and SERCA-2 play a pivotal role in the hypoxic exacerbation of VLDL-mediated effects on cardiac calcium handling. Potentiation of VLDL's effects under hypoxia is explained, at least in part, by hypoxic upregulation of the expression of VLDL-receptor.