银杏内酯B 对星形胶质细胞氧化损伤的保护作用

目的:探讨银杏内酯B对过氧化氢(H_2O_2)诱导的星形胶质细胞损伤的保护作用及可能机制。方法:星形胶质细胞传代培养,分为阴性对照组(以正常培养液培养),氧化损伤组(100μmol·L~(-1)的H_2O_2作用12 h),银杏内酯B低剂量组(1×10~(-6) mol·L~(-1)银杏内酯B孵育24 h后,加入H_2O_2作用12 h)和银杏内酯B高剂量组(1×10~(-4) mol·L~(-1)银杏内酯B孵育24 h后,加入H_2O_2作用12 h),MTT比色法检测细胞存活率,流式细胞仪检测细胞活性氧(ROS)水平,分光光度计检测上清液中超氧化物歧化酶(SOD)、如谷胱甘肽过氧化物酶(GSH-Px)活性及丙二醛(MDA)的含量。结果:银杏内酯B能抑制氧化损伤引起的细胞活性的下降,降低星形胶质细胞内ROS的生成,促进SOD、GSH-Px水平的升高及MDA水平的下降。结论:银杏内酯B通过提高细胞内SOD、GSH-Px含量,降低细胞内MDA含量发挥其较强的抗氧化作用,从而为其用于治疗神经系统疾病提供可靠的实验依据。     

铜藻多糖对H2O2诱导的HaCaT细胞氧化应激的保护作用

为探究铜藻多糖(Sargassum horneri polysaccharides, SHP)对H₂O₂诱导的人角质形成细胞(HaCaT)氧化应激损伤的保护作用,测定了SHP对总抗氧化能力(T-AOC)、DPPH自由基、羟自由基(·OH)和超氧阴离子自由基(O₂^·-)的清除作用,以评价SHP的体外抗氧化能力,并建立H₂O₂诱导HaCaT细胞氧化损伤模型;通过测定细胞存活率、细胞活性氧以及酶活,评价SHP对HaCaT细胞氧化损伤的保护作用。结果表明,当SHP为1 mg/mL时,DPPH的清除率为68%、·OH清除能力65.48 U/mL;在SHP为3 mg/mL时,O₂^·-清除能力为84.86 U/mL,T-AOC为33.55。SHP能显著提高H₂O₂诱导氧化损伤的HaCaT细胞活力,其中经100μg/mL SHP处理后,HaCaT细胞存活率由56.85%提高到80.57...     

奥拉帕尼对黑素瘤细胞的作用及机制研究

目的:探讨奥拉帕尼对黑素瘤细胞的作用及其机制。方法:应用不同浓度的奥拉帕尼处理黑素瘤细胞,利用CCK8检测肿瘤细胞活性。应用Western blot技术检测奥拉帕尼处理黑素瘤细胞后肿瘤细胞内凋亡及周期相关蛋白表达水平。结果:与对照组相比,5μM奥拉帕尼处理黑素瘤A2058细胞即可抑制肿瘤细胞活性(85.53±2.593)%。随着奥拉帕尼处理浓度倍增对黑素瘤细胞活性的抑制作用越强。在10μM、20μM、40μM、80μM奥拉帕尼处理浓度下,黑素瘤细胞活性分别是(68.88±1.484)%、(47.21±1.759)%、(33.04±1.261)%、(28.17±1.731)%。奥拉帕尼处理黑素瘤细胞后可促进肿瘤细胞内凋亡相关蛋白PARP1剪切体表达增加,并可抑制细胞周期相关蛋白cyclin D1的表达。结论:奥拉帕尼通过促进黑素瘤细胞凋亡及抑制肿瘤细胞周期蛋白表达的机制发挥抑制黑素瘤细胞活性的作用。     

甘草次酸通过PI3K-AKT途径抑制H2O2所致大鼠心肌细胞氧化损伤

目的:研究甘草次酸对H_2O_2所致大鼠心肌细胞氧化损伤的影响及其可能机制。方法:采用H_2O_2处理建立H9c2大鼠心肌细胞氧化损伤模型后,比较模型中ROS生成和细胞凋亡比例,使用不同浓度的甘草次酸孵育H9c2细胞24、48h后,通过流式细胞仪检测ROS的生成量,Annexin V-FITC/PI双标记流式细胞术检测凋亡率,蛋白质印迹法检测检PI3K、AKT1、p-AKT蛋白的表达。结果:H9c2大鼠心肌细胞氧化损伤模型中ROS生成和细胞凋亡率分别为(49.33±3.23)%和(33.89±1.45)%,与对照组相比有显著差异;100μmol/L和200μmol/L的甘草次酸作用24 h后,H9c2大鼠心肌细胞氧化损伤模型中表达ROS细胞的比例(35.39±1.24)%和(30.46±0.95)%,凋亡细胞比例分别为(29.47±3.15)%和(23.17±1.46)%,当作用48 h后,H9c2大鼠心肌细胞氧化损伤模型中表达ROS细胞的比例(42.67±1.89)%和(35.49±1.63)%,凋亡细胞比例分别为(40.22±3.06)%和(35.26±2.78)%,与对照组相比有显著性差异;使用渥曼青霉素后,各甘草次酸组的与对照组无显著性差异。结论:甘草次酸可能通过PI3K-AKT途径抑制H_2O_2所致大鼠心肌细胞氧化损伤。     

H2O2诱导Neuro-2a细胞死亡机理的研究

细胞内线粒体呼吸链过程中的电子漏和神经细胞代谢的酶类如单胺氧化酶(MAO)等可产生活性氧物质(ROS)如H2O2等.ROS对细胞有毒性作用,导致细胞死亡,在许多疾病特别是神经退行性疾病中具有重要作用.我们用H2O2诱导N-2a神经母细胞瘤细胞,利用光镜、荧光显微镜、透射电镜观察了诱导的N-2a细胞的死亡,结果表明其死亡形式不同于典型的细胞凋亡,而类似于Ⅱ型神经细胞编程性死亡,死亡细胞染色质呈团块状凝集,细胞核膜仍保持完整.DNA不降解形成ladder,且不需要caspase-3,1的活性,但是H2O2诱导的Neuro-2a细胞死亡可以被Bcl-XL抑制.我们的结果可以说明,ROS介导的细胞毒性作用是导致Ⅱ型神经细胞编程性死亡的一个原因.     

ABA诱导蚕豆气孔保卫细胞H2O2的产生

以蚕豆叶片下表皮为材料,将荧光探针HPTS导入蚕豆气孔保卫细胞内,利用荧光光谱和激光共聚焦显微技术,检测了ABA诱导蚕豆气孔关闭过程中H     

厄贝沙坦对链脲佐菌素和过氧化氢诱导的β细胞氧化损伤保护作用

目的 探讨厄贝沙坦对链脲佐菌素(STZ)和过氧化氢(H₂O₂)诱导的β细胞损伤影响。方法 (1)将NIT-1细胞分为对照组及1、2、5 mmol/L STZ和300、500μmol/L H₂O₂组,处理30 min后,采用Hoechst 33342法检测各组细胞凋亡形态变化,流式细胞术检测细胞凋亡率,RT-qPCR检测Caspase3 mRNA水平。(2)将NIT-1细胞分为STZ及0.001、0.01、0.1 mmol/L厄贝沙坦组,作用24、48和72 h。(3)将NIT-1细胞分为H₂O₂及0.001、0.01、0.1 mmol/L厄贝沙坦组,作用24、48和72 h。采用流式细胞术检测细胞凋亡率和活性氧(ROS)含量,RT-qPCR检测血管紧张素II型1受体(AT1R)mRNA表达。结果 Hoechst 33342染色显示,5 mmol/L STZ组相较于1、2 mmol/L STZ组,500μmol/L H₂O_2<...     

氧化苦参碱对H2O2诱导的L6成肌细胞凋亡的影响

研究氧化苦参碱对L₆大鼠成肌细胞H<>sub>2O₂凋亡的影响．采用过氧化氢损伤L₆大鼠成肌细胞的方法,建立L₆大鼠成肌细胞H₂O₂凋亡模型．使用剂量为0.3,0.15,0.75 g/L的氧化苦参碱处理细胞．应用MTT法统计存活率和流式细胞仪检测细胞周期及凋亡率,用DAPI荧光染色、HE染色以及Bax和Bcl-2抗体鉴定损伤程度,Western blot检测蛋白质差异．结果表明,H₂O₂损伤的成肌细胞存活率降低,凋亡率增加．各种剂量氧化苦参碱能提高成肌细胞的存活率,促使Bcl-2增高,Bax降低．对成肌细胞的保护程度随氧化苦参碱剂量增加而增强,在剂量为0.3 g/L时,效果显著,其次是0.15、0.75 g/L的氧化苦参碱．其生理生化机制是氧化苦参碱保护₂O₂通过NFκB信号通路造成的大鼠成肌细胞凋亡模型．结果显示,氧化苦参碱具有作为新的抗氧化药物的潜力．     

银杏叶提取物对过氧化氢诱导的星形胶质细胞氧化损伤的保护作用

目的 研究银杏叶提取物（EGb761）对H2O2所致星形胶质细胞氧化损伤的保护作用。方法 用不同浓度的EGb761预处理细胞,再加入H2O2,通过噻唑蓝（MTT）实验、线粒体跨膜电位（△ψm）及细胞色素C释放实验、DNA损伤实验及半胱氨酰天冬氨酸特异性蛋白酶-3（Caspase-3）活性测定,观察EGb761对细胞存活率、线粒体膜通透性、DNA氧化损伤及Caspase-3活性的影响。结果 EGb761能明显降低Hz02对星形胶质细胞的氧化损伤,提高细胞的存活率;维持线粒体膜的完整性,抑制跨膜电位的耗散和细胞色素C的释放;抑制Caspase-3的活化和DNA的降解。结论 EGb761具有清除活性氧,减轻H2O2所致星形胶质细胞的氧化损伤,对星形胶质细胞有保护作用。     

槲皮素对过氧化氢所致PC-12细胞氧化损伤的保护作用

目的:研究槲皮素(quercetin)是否对过氧化氢所致PC-12细胞氧化损伤具有保护作用,以及可能的保护机制。方法:用PC-12细胞建立H2O2氧化损伤模型;测定SOD、T-AOC生化指标判断细胞抗氧化能力;半定量RT-PCR法检测糖皮质激素受体(GR)基因转录水平。结果:①MTT结果:H2O2能使细胞活力显著降低(P0.01),槲皮素的预孵处理能够明显减轻H2O2对PC-12细胞的氧化损伤(P0.050.01)。②SOD活性结果:H2O2作为氧化损伤因素使得细胞SOD活性应激上升(P0.01),Qu组细胞SOD活性维持在较低水平(P0.01)。③T-AOC结果:槲皮素能够显著提高PC-12细胞的总抗氧化能力(P0.01)。④半定量RT-PCR结果:H2O2使PC-12细胞GR基因转录水平显著降低,槲皮素能够减轻其转录所受影响(P0.01)。结论:槲皮素与PC-12细胞的共孵育,提高了细胞整体的抗氧化能力,维持了GR基因的转录水平,继而保护细胞免受后续H2O2的氧化损伤和炎症反应,维持细胞生化环境的稳态。     

抗原负载DCs诱导的CIK细胞对B16黑色素瘤抑制作用的形态学观察

目的:探讨抗原负载树突状细胞(dentritic cells,DCs)诱导的CIK(cytokine induced killer)细胞对B16黑色素瘤的抑瘤作用。方法:分离、培养DC和CIK细胞,取部分DC进行肿瘤抗原负载,将其与CIK细胞按1:10的比例共培养3d,即为抗原负载的DC-CIK。建立B16黑色素瘤小鼠模型,分别于瘤周围皮下注射经Brdu标记的CIK、DC-CIK、抗原负载DC-CIK。按注射细胞进行分组,测量注射前后各组小鼠的瘤体积,计算抑瘤率,比较其抑瘤作用。应用免疫组化方法和透射电镜观察抗原负载DC-CIK细胞在皮肤中的分布及杀伤肿瘤细胞的形态学表现。结果:抗原负载DC诱导的CIK(细胞组抑瘤率(86.57%)高于CIK细胞组(33.34%,P<0.05)和DC-CIK细胞组(61.08%,P<0.05);光镜下抗原负载DC-CIK细胞主要分布在皮下组织,癌组织周围,特别是癌巢周边。透射电镜下抗原负载DC-CIK细胞体积大,核有切迹,细胞质内细胞器丰富,粗面内质网扩张。细胞表面有突起,与肿瘤细胞密切接触。大量肿瘤细胞凋亡、坏死。结论:CIK细胞经抗原负载DC诱导后抑瘤作用明显强于单纯CIK细胞和DC-CIK细胞。     

Calcium Plays a Complex Role in the Regulation of Melanogenesis in Murine B16 Melanoma Cells

To learn more of the role of calcium in the regulation of melanogenesis, we have used direct manipulation of medium calcium and pharmacological modulation of intracellular calcium to examine the consequences on unstimulated and cyclic AMP elevated tyrosinase activity and melanin synthesis and distribution in B16 melanoma cells. In unstimulated cells, calcium is clearly inhibitory to tyrosinase activity. However, in cells stimulated with cAMP-elevating agents the requirement for extracellular calcium was changed such that cells required a minimum of 0.4–0.6 mmol medium calcium for maximum tyrosinase response to these agents. Paradoxically, pharmacologically increasing intracellular calcium in cAMP-stimulated cells with ionophore inhibited tyrosinase activity, and the calcium-lowering agent TMB8 and the calcium channel blocker verapamil both stimulated tyrosinase activity. When melanin synthesis was measured in cAMP-stimulated cells, TMB8 was found to significantly increase the sensitivity and the maximum melanogenic response to α-MSH, suggesting the presence of at least one level of endogenous calcium inhibitory control operative in these cells. In addition, TMB8 changed the distribution of melanin between the cell and the medium such that, in the presence of α-MSH and TMB8, significantly more melanin was secreted into the medium. These data suggest that calcium is required for several steps in melanogenesis, having an apparently inhibitory effect on pre-tyrosinase activity in unstimulated cells, but also showing evidence of a positive role in cyclic AMP-stimulated tyrosinase activity, as well as a further possible inhibitory role in melanin movement or secretion.     

Progressive Effects of Phloridzin on Melanogenesis in B16 Mouse Melanoma Cells

When we studied the effects of polyphenols from apple fruits on melanogenesis in B16 mouse melanoma cell lines, phloridzin had dose-dependent progressive effects on melanogenesis between 10 and 500 μg/ml without inhibiting cell growth. At a concentration of 500 μg/ml, phloridzin increased the melanin content in the cells to 181% of that in control cells. In contrast, phloretin, the aglycon of phloridzin, did not activate melanogenesis in the cells and was cytotoxic at a concentration of 5 μg/ml. Phloridzin increased the activity of tyrosinase to 223% of that in control cells. Furthermore, phloridzin inhibited the activity of protein kinase C (PKC), which is recognized to regulate tyrosinase activity. The inhibition of PKC activity continued for 120min from the addition of phloridzin. Therefore, we estimated that the activation of melanogenesis by phloridzin resulted from the increase of tyrosinase activity caused by the inhibition of PKC activity.     

皮下种植黑色素瘤对小鼠血液中脂肪和氨基酸代谢的影响*

目的:探讨皮下种植黑色素瘤对小鼠血液中相关脂肪和氨基酸代谢的影响。方法:野生型小鼠皮下种植B16黑色素瘤细胞,两周后观察小鼠并取不同的组织称重,检测血液中甘油三酯、葡萄糖、脂肪酸、炎症因子的水平。利用质谱方法检测血液中氨基酸的水平。结果:野生型小鼠皮下肿瘤种植2周后体重没有明显变化,脾脏和肝脏的重量明显增加,皮下脂肪组织和腹腔脂肪组织的重量没有明显变化。血液中甘油三酯的水平明显增高,葡萄糖和甘油的水平明显下降。血液中炎症因子Interleukin 6(IL6)和Interferon gamma(IFNγ)的水平明显增加。血液的质谱结果显示有四种氨基酸的水平有明显变化,其中胱氨酸(Cystine)增加了约30倍,丝氨酸(Serine)、谷氨酰胺(Glutamine)和色氨酸(Tryptophan)分别有不同程度的降低。结论:皮下黑色素瘤显著影响小鼠机体营养状态和炎症,并特异性影响血液中氨基酸的代谢。     

Inhibitory Effects of Whisky Polyphenols on Melanogenesis in Mouse B16 Melanoma Cells

Whisky exerts an inhibitory effect on melanogenesis in B16 cells, the anti-melanogenic activity being positively correlated with the aging period and anti-oxidative activity of whisky. We examined the correlation between the inhibition of melanogenesis and the concentration of each compound in various whiskies to evaluate the importance of 11 different whisky polyphenols, including ellagic acid, gallic acid and lyoniresinol, in the anti-melanogenic activity of whisky. The concentration of all the compounds was positively correlated with the anti-melanogenic activity of whisky. Ellagic acid, gallic acid and lyoniresinol were the predominant polyphenols in the whiskies measured by HPLC. These three compounds also significantly inhibited the melanogenesis and tyrosinase activity in B16 cells. Ellagic acid, gallic acid and lyoniresinol were confirmed as the major participants in the anti-melanogenic activity of whisky.     

转染人核糖核酸酶抑制因子基因对B16黑色瘤细胞及肿瘤转移的影响(英)

人核糖核酸酶抑制因子(human ribonuclease inhibitor, RI)是一种细胞质中分子质量为50 ku的酸性糖蛋白.RI能抑制核糖核酸酶A（RNase A）的活性, RNase A与血管生成因子（angiogenin,Ang）的氨基酸有着高度保守的同源序列.Ang是RNase A超家族的一员,RI通过与RNase A和Ang的紧密结合而抑制其活性.血管生成及新血管的形成, 是肿瘤发生和转移的必要条件.所以抗血管生成将是一种很有希望的对抑制肿瘤生长和转移的有效方法.实验显示RI能有效地抑制肿瘤诱导血管的生成.RI由含有许多亮氨酸重复序列的多肽组成.含有这样重复序列的100多种蛋白质显示了广泛的功能,包括细胞周期调节,DNA修复,对细胞外基质相互作用以及抑制酶活性等.RI被认为是胚胎发育,创伤愈合及肿瘤发生中新血管形成的一种调节因子.RI定位于染色体的11p15.5,与ras基因邻近,在肿瘤病人中经常存在染色体11p15.5部位的变异和异常.RI可能与细胞的生长和分化有关, 因此,RI 可能还具有尚未知的生物学作用.为了进一步了解RI的潜在功能以及探讨RI与肿瘤浸润、转移的关系, 将人的核糖核酸酶抑制因子基因的cDNA通过逆转录包装细胞PA317,并转染到B16小鼠黑色瘤细胞中, 用转染空载体和未转染的B16细胞作为对照.通过PCR, RT-PCR, 蛋白质免疫印迹, 免疫荧光分析鉴定,获得稳定表达人核糖核酸酶抑制因子的细胞株.结果显示, 转染的RI基因在体外能显著地抑制细胞增殖和细胞迁移,增加了细胞的粘附以及改善细胞的恶性形态,B16,B16 pLNCX,B16 pLNCX-RI 3种细胞的倍增时间分别为(24.98±0.16) h, (25.62±0.28) h, (32.64±1.11) h.与对照组相比,转RI的细胞粘附率增加17.8%和19.5%而迁移降低了61.4%和60%.转RI的细胞比对照组细胞较平展,核仁和分裂相较少,胞质嗜碱性减弱,提示细胞增殖活性降低和恶性表型的改善. 将3种B16细胞静脉注射到C57BL/6小鼠中, 结果表明, 转染RI基因的实验组显著地抑制了肿瘤的转移, 与两个对照组相比,荷瘤小鼠有更长的存活时间, 少得多的转移节结, 更低的肿瘤血管密度和肺重量.结果显示,RI的表达可能与黑色瘤的转移有关, 提示RI能显著地抑制肿瘤的转移,可能由于其与抑制血管作用,增加细胞粘附,降低细胞迁移及增殖有关.     

Antitumor Activity of T Cells Generated from Lymph Nodes Draining the SEA-expressing Murine B16 Melanoma and Secondarily Activated with Dendritic Cells

The successful use of tumor-draining lymph nodes (TDLN) as a source of effector cells for cancer immunotherapy depends largely on the immunogenicity of the tumor drained by the lymph nodes as well as the methods for secondary in vitro T cell activation and expansion. We transferred the bacterial superantigen staphylococcal enterotoxin A (SEA) gene into B16 murine melanoma tumor cells, and used them to induce TDLN (SEA TDLN) in syngeneic hosts. Wild-type (wt) TDLN induced by parental B16 tumor was used as a control. In vitro, SEA TDLN cells proliferated more vigorously, produced more IFNγ and demonstrated higher CTL activity than wt TDLN cells when activated with anti-CD3/anti-CD28/IL-2. In vivo, SEA TDLN cells mediated tumor eradication more effectively than similarly activated wt TDLN cells (p<0.01). Furthermore, use of dendritic cells (DC) plus tumor antigen in vitro in addition to anti-CD3/anti-CD28/IL-2 stimulation further amplified the immune function and therapeutic efficacy of SEA TDLN cells. DC-stimulated SEA TDLN cells eliminated nearly 90% of the pulmonary metastasis in mice bearing established B16 melanoma micrometastases. These results indicate that enforced expression of superantigen SEA in poorly immunogenic tumor cells can enhance their immunogenicity as a vaccine in vivo. The combined use of genetically modified tumor cells as vaccine to induce TDLN followed by secondary stimulation using antigen-presenting cells and tumor antigen in a sequential immunization/activation procedure may represent a unique method to generate more potent effector T cells for adoptive immunotherapy of cancer.     

蛇毒金属蛋白酶抑制剂抗小鼠黑色素瘤肺转移

探讨蛇毒金属蛋白酶抑制剂BJ46a抗肿瘤侵袭转移作用。以BJ46a为目的基因,选择杆状病毒表达系统生产重组BJ46a蛋白,ProBondTM亲和层析纯化后处理黑色素瘤细胞B16,经尾静脉接种C57BL/6小鼠,建立B16细胞实验性肺转移模型,20天后以颈椎脱臼法处死小鼠,观察肺组织病理学变化。结果表明：不同浓度重组BJ46a蛋白处理组肺部转移瘤数分别为1.1±0.83、0.9±0.7,明显低于对照组（6.3±3.00,P<0.001）和空白对照组（10.7±5.73,P<0.001）,光镜下对照组肿瘤病理学征象明显,而重组BJ46a蛋白处理组瘤结节小。研究结果首次证明了重组BJ46a蛋白能抑制小鼠黑色素瘤细胞的侵袭转移,为其作为抗肿瘤侵袭转移药物的进一步研制和开发应用提供理论依据和前提条件。探讨蛇毒金属蛋白酶抑制剂BJ46a抗肿瘤侵袭转移作用。以BJ46a为目的基因,选择杆状病毒表达系统生产重组BJ46a蛋白,ProBond™ 亲和层析纯化后处理黑色素瘤细胞B16,经尾静脉接种C57BL/6小鼠,建立B16细胞实验性肺转移模型,20天后以颈椎脱臼法处死小鼠,观察肺组织病理学变化。结果表明：不同浓度重组BJ46a蛋白处理组肺部转移瘤数分别为1.1±0.83、0.9±0.7,明显低于对照组（6.3±3.00,P<0.001）和空白对照组（10.7±5.73,P<0.001）,光镜下对照组肿瘤病理学征象明显,而重组BJ46a蛋白处理组瘤结节小。本研究结果首次证明了重组BJ46a蛋白能抑制小鼠黑色素瘤细胞的侵袭转移,为其作为抗肿瘤侵袭转移药物的进一步研制和开发应用提供理论依据和前提条件。     

Ca2+‐Inactivated K+ Current is Modulated by Endothelin‐1 in B‐16 Murine Melanoma Cells

It is well established that endothelin‐1 (ET‐1) plays a role in differentiation and proliferation in a variety of cells such as fibroblasts and human melanoma cells via a receptor‐mediated mechanism. However, whether ET‐1 modulates ion channel activity in these cell types is still unknown. In this report, we recorded the voltage‐dependent outward K⁺ current in cultured B16 melanoma cells using the patch‐clamp technique. Biophysical and pharmacological properties of the K⁺ current, and the effect of ET‐1 on the K⁺ current were investigated. When cells were loaded with a Ca²⁺‐chelating agent (EGTA or BAPTA), the K⁺ current amplitude gradually increased with time after establishment of the whole cell configuration. Replacement of Ca²⁺ with Co²⁺ in the extracellular medium caused no significant modulation of the K⁺ current amplitude. Addition of BaCl₂ or quinidine to the extracellular solution reduced the K⁺ current amplitude, whereas the K⁺ current was insensitive to tetraethylammonium. ET‐1 (10 nM) reversibly decreased the K⁺ current amplitude and accelerated the decay of the K⁺ current. The ET‐1‐induced inhibitory effect displayed no desensitization following repeated ET‐1 application. Pretreatment with pertussis toxin (PTX) or perfusion of cells with the protein kinase C (PKC) inhibitor H‐7 abolished the inhibitory effect of ET‐1 on the K⁺ current. We conclude that the outward K⁺ current recorded in murine B‐16 melanoma cells represents a Ca²⁺‐inactivated K⁺ current, and that the inhibitory effect of ET‐1 on the K⁺ current may reveal a novel mechanism to control the differentiation and proliferation of melanoma cells.     

H2O2对红细胞抗原性与LPO影响的FCM研究

用流式细胞计（flow cytometry,FCM）测定H₂O₂损伤后的红细胞（RBC）与IgG的结合能力,并直接检测细胞自发荧光的变化,以研究H₂O₂对RBC抗原性和脂质过氧化（LPO）荧光产物生成的影响.结果表明RBC抗原性和自发荧光变化与H₂O₂浓度和作用时间有关,抗原性变化对H₂O₂更敏感,比引起自发荧光明显增强所需H₂O₂浓度低两个数量级;还发现了RBC抗原性和自发荧光的变化与细胞的散射光有相关性.