食品添加剂亚硫酸钠对肝细胞蛋白合成功能的影响

目的探讨食品添加剂亚硫酸钠对肝脏蛋白合成功能的可能影响。方法以不同浓度的亚硫酸钠(Na2SO3)作用于正常人二倍体肝细胞株HL-7702(简称L-02)细胞,终浓度分别为0.039、0.156、0.625和2.5 mmol/L,并设阴性对照组和阳性对照组(体积分数为0.3%的乙醇)。采用生化分析法检测不同接触时间后各染毒组肝细胞培养上清中天冬氨酸转氨酶(AST)、丙氨酸转氨酶(ALT)、总蛋白和白蛋白含量。结果①Na2SO3染毒24 h,随着染毒浓度的增加,各组肝细胞培养上清中AST活性逐渐升高,0.625和2.5 mmol/L组与阴性对照组比较,差异有统计学意义(P0.05或P0.01)。而在染毒48和72 h后,各染毒组与对照组比较,无统计学差异;当作用24和48 h后,随Na2 SO3浓度增加,各组肝细胞培养上清中ALT活性逐渐升高,与对照组比较,差异有统计学意义(P0.05或P0.01);染毒72 h后,各染毒组与对照组之间的ALT活性无差异。②Na2SO3染毒24、48和72 h后,各染毒组肝细胞培养上清中白蛋白和总蛋白的含量与阴性对照组比较无统计学差异(P0.05)。结论亚硫酸钠染毒不同时间后可能对肝细胞膜结构造成一定影响使培养上清中转氨酶活性明显增加,但对肝细胞的蛋白合成功能无明显影响。     

亚硫酸钠对人胚肾293细胞的毒性作用与胞内蛋白水平变化的关系

目的研究食品添加剂亚硫酸钠(Na2SO3)对人胚肾293细胞(HEK293)的毒性作用与胞内重要蛋白质p53、增殖细胞核抗原(PCNA)和三磷酸腺苷(ATP)结合转运子G2(ABCG2)含量改变之间的关系。方法采用细胞毒性试验(MTS)法观察Na2SO3对HEK293细胞的毒性作用,用蛋白印记法检测HEK293细胞中p53、PCNA和ABCG2蛋白水平。结果0.625～10mmol/L NaSO3处理组的细胞活性与对照组相比,差异有统计学意义(P0.01),说明NaSO3对HEK293细胞有明显的毒性作用;蛋白印记分析发现最高剂量组10mmol/L Na2SO3可同时降低细胞内p53、PCNA和ABCG2蛋白水平,而其余剂量组0.039～2.5mmol/L Na2SO3对HEK293细胞内p53、PCNA和ABCG2蛋白的水平无明显影响。结论在本试验条件下,当Na2SO3的接触浓度达到一定水平时对人胚肾293细胞具有明显的毒性作用,这种毒性作用很可能与其降低肾细胞内的蛋白水平,干扰肾细胞的正常功能相关。     

亚硝酸钠与亚硫酸钠联合毒性对人胚肾细胞HEK-293 Apaf-1信号通路的影响

目的探讨亚硝酸钠与亚硫酸钠联合毒性对人胚肾细胞HEK-293 Apaf-1信号通路的影响。方法取处于对数生长期的HEK-293细胞,用亚硝酸钠、亚硫酸钠染毒。采取3×3析因设计:对照组(0. 0 mmol/L Na2NO2+0. 0 mmol/L Na2SO3)、低亚硝酸钠组(低N,3. 0 mmol/L Na2NO2)、高亚硝酸钠组(高N,12. 0 mmol/L Na2NO2)、低亚硫酸钠组(低S,4. 0 mmol/L Na2SO3)、高亚硫酸钠组(高S,16. 0 mmol/L Na2SO3)、低N低S组(3. 0 mmol/L Na2NO2+4. 0 mmol/L Na2SO3)、低N高S组(3. 0 mmol/L Na2NO2+16. 0 mmol/L Na2SO3)、高N低S组(12. 0 mmol/L Na2NO2+4. 0 mmol/L Na2SO3)、高N高S组(12. 0 mmol/L Na2NO2+16. 0 mmol/L Na2SO3),培养24 h,MTT法检测细胞活力,酶联免疫吸附法测定培养液中Apaf-1、Caspase9和Bax水平。结果低N组存活率略高于对照组(P0. 05),Bax、Apaf-1和Caspase9蛋白表达水平略低于对照组(P0. 05);高N组HEK-293存活率低于对照组及低N组(P0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于对照组及低N组(P 0. 01);低S组HEK-293存活率低于对照组(P 0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于对照组(P0. 01);高S组HEK-293存活率低于对照组及低S组(P 0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于对照组及低S组(P0. 01);低N高S组HEK-293存活率低于低N低S组(P0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于低N低S组(P0. 01);高N高S组HEK-293存活率低于高N低S组(P0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于高N低S组(P 0. 01);高N低S组HEK-293存活率低于低N低S组(P 0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于低N低S组(P0. 01);高N高S组HEK-293存活率低于低N高S组(P0. 01),Bax、Apaf-1和Caspase9蛋白表达水平高于低N高S组(P0. 01);在低N低S组剂量组,Apaf-1低于两者单独作用时的水平之和(P0. 01)。Apaf-1与Bax,Apaf-1与Caspase9正相关关系明显(P0. 01); Na2NO2与Na2SO3单独作用时均可影响Bax、Apaf-1和Caspase9水平的变化(P0. 05或P0. 01); Na2NO2与Na2SO3对Apaf-1的交互作用明显(P0. 01),对Bax和Caspase9交互作用不明显(P0. 05)。结论 Apaf-1通路可能参与了Na NO2与Na2SO3致人胚肾细胞HEK-293的凋亡过程; Na2NO2与Na2SO3对Apaf-1存在交互作用,在N低S组表现为拮抗作用。     

乙酰辅酶A羧化酶反义寡核苷酸对非酒精性脂肪肝细胞模型的作用

目的观察乙酰辅酶A羧化酶(ACC)反义寡核苷酸(ASODN)对HL-7702肝细胞脂肪变性的影响。方法用计算机软件设计并合成特异性靶向ACC的硫代修饰ASODN。用静脉脂肪乳剂体外培养正常HL-7702肝细胞48 h,制备体外脂肪肝细胞模型。以脂质体法将ACC-ASODN转染至脂肪肝细胞模型,设置空白组(HL-7702肝细胞组)、模型组(脂肪肝细胞模型组)、低高2个浓度实验组(5,10μmol·L^-1ACC-ASODN转染组)。以ACC-ASODN转染入脂肪肝细胞模型24 h后,放射性同位素技术测定ACC酶活性,HPLC法测定丙二酰辅酶A含量,放射性同位素技术测定肉碱棕榈酰转移酶Ⅰ(CPT I)活性,用全自动生化分析仪测定4组肝细胞内三酰甘油(TG)含量。结果 ACC-ASODN转染入脂肪肝细胞模型24 h后,空白组、模型组及低、高2个浓度实验组的肝细胞ACC活性(U)分别是0.74,0.33,0.20,0.18;这4组的细胞内丙二酰辅酶A含量(nmol·L^-1)分别是14.3,12.4,7.5,6.8;这4组的细胞CPTⅠ活性(U)分别是1.33,1.47,3.85,3.95;这4组的TG含量分别是0.20,0.52,0.37,0.28 mmol·L^-1。模型组与空白组的以上几项指标比较,差异均有统计学意义(均P<0.05);实验组与模型组的以上几项指标比较,差异均有统计学意义(均P<0.01)。结论 ACC-ASODN作用于肝细胞,通过抑制肝细胞ACC活性,使TG含量下降,从而减轻肝细胞脂肪变性。     

二甲基甲酰胺对HL7702肝细胞毒性及线粒体膜电位的影响北大核心CSCD

目的观察二甲基甲酰胺(DMF)对HL7702肝细胞的细胞活力、凋亡及线粒体膜电位的影响,探讨DMF引起肝细胞凋亡的可能机制。方法 HL7702肝细胞给予50、100、150、200和250 mmol/L DMF处理,于24 h后检测其细胞存活率,乳酸脱氢酶(LDH)释放量。根据细胞毒性测试结果设置对照组及DMF染毒组(200 mmol/L)。流式细胞术检测DMF对HL7702细胞凋亡以及对线粒体膜电位的影响。结果 DMF剂量依赖性地降低HL7702细胞的存活率,其中150、200和250 mmol/L DMF组与对照组相比,细胞存活率明显降低;并且,随着DMF染毒浓度增加,释放至细胞外的LDH的含量增加,与DMF浓度呈正相关。200 mmol/L DMF染毒24 h后,与对照组相比,细胞凋亡率增加,差异有统计学意义(P<0.001),线粒体膜电位降低,差异也有统计学意义(P<0.001)。结论 DMF对HL7702细胞的毒性作用具有剂量依赖性,DMF引起HL7702线粒体膜电位的改变与DMF导致细胞凋亡有关。     

二甲基甲酰胺对HL7702肝细胞毒性及线粒体膜电位的影响

目的观察二甲基甲酰胺(DMF)对HL7702肝细胞的细胞活力、凋亡及线粒体膜电位的影响,探讨DMF引起肝细胞凋亡的可能机制。方法 HL7702肝细胞给予50、100、150、200和250 mmol/L DMF处理,于24 h后检测其细胞存活率,乳酸脱氢酶(LDH)释放量。根据细胞毒性测试结果设置对照组及DMF染毒组(200 mmol/L)。流式细胞术检测DMF对HL7702细胞凋亡以及对线粒体膜电位的影响。结果 DMF剂量依赖性地降低HL7702细胞的存活率,其中150、200和250 mmol/L DMF组与对照组相比,细胞存活率明显降低;并且,随着DMF染毒浓度增加,释放至细胞外的LDH的含量增加,与DMF浓度呈正相关。200 mmol/L DMF染毒24 h后,与对照组相比,细胞凋亡率增加,差异有统计学意义(P0.001),线粒体膜电位降低,差异也有统计学意义(P0.001)。结论 DMF对HL7702细胞的毒性作用具有剂量依赖性,DMF引起HL7702线粒体膜电位的改变与DMF导致细胞凋亡有关。     

羧甲基葡聚糖体外抗肿瘤作用的研究

目的研究不同取代度羧甲基葡聚糖(CMG)的体外抗肿瘤作用。方法以HL-7702正常肝细胞、HepG-2肝癌细胞、MGC-803胃癌细胞为实验材料,通过四甲基偶氮唑盐(MTT)比色法分析。结果各种取代度的CMG对HL-7702的生长影响较小,但对HepG-2和MGC-803的抑制作用明显,并且随浓度升高对HepG-2、MGC-803的抑制作用也随之增强,尤以取代度为0.556的CMG2最为显著。CMG2浓度达到500μg/mL时对HepG-2的生长抑制率为54.3%,浓度为1 000μg/mL时对MGC-803抑制率达到51.3%。结论在体外实验中,取代度0.55左右的CMG能有效抑制HepG-2肝癌细胞、MGC-803胃癌细胞的生长。     

番茄红素对CCl4诱导的正常肝细胞株HL-7702损伤的影响

目的体外观察番茄红素对人正常肝细胞株HL-7702细胞活力及凋亡的影响,探讨其对肝细胞的保护作用。方法体外培养人正常肝细胞株HL-7702,建立CCl4肝损伤模型,终浓度为2、5、10μmol·L-1的番茄红素干预处理,MTT法测定细胞活性、Horchest33342染色及TUNEL检测观察细胞凋亡。结果番茄红素在2～10μmol·L-1浓度范围内的对肝细胞无毒性,可抑制CCl4所致肝细胞活性下降,减少CCl4所致的肝细胞凋亡,一定剂量范围内与番茄红素浓度相关。结论番茄红素对正常肝细胞HL-7702具有保护作用。     

2种静脉铁剂对HL-7702正常肝细胞的毒性作用

目的 探究羧基麦芽糖铁(ferric carboxymaltose,FCM)及蔗糖铁(iron saccharate,IS)对HL-7702正常肝细胞的毒性及氧化应激作用.方法 选用浓度为2、1、0.5、0.25、0.125、0.062 mg·mL-1的静脉铁剂与HL-7702细胞共培养24h,MTT法和乳酸脱氢酶(L...     

天麻素通过激活AMPK通路减少油酸诱导的HL-7702细胞脂肪蓄积

目的研究天麻素(GSTD)对油酸(OA)诱导的HL-7702细胞脂肪蓄积的抑制作用,并探讨其可能的细胞信号通路。方法以噻唑蓝(MTT)法测定GSTD对HL-7702细胞存活率的影响;以1 mmol·L-1的OA处理24 h诱导细胞脂肪变性,同时加入不同浓度的GSTD,油红O(ORO)染色观察细胞脂肪蓄积情况并测定细胞内三酰甘油(TG)含量;以Western blot检测GSTD处理后细胞中AMPKα和ACC的磷酸化水平;以compound C处理细胞,研究其对GSTD药效的影响。结果 GSTD浓度≤3 386.5μmol·L-1时对HL-7702细胞没有明显毒性。OA处理24 h后细胞中出现大量脂滴蓄积,TG含量明显增加,但同时加入浓度为169.3或338.7μmol·L-1的GSTD可明显抑制HL-7702细胞的脂肪蓄积,并使TG含量分别平均下降35%和43.6%(与单加OA的细胞比较P<0.01)。GSTD处理后能时间和浓度依赖性地增加细胞中的p-AMPKα和p-ACC水平,compound C能完全阻断GSTD对AMPK通路的激活作用以及减少肝细胞TG蓄积的作用。结论 GSTD可明显抑制OA诱导的HL-7702细胞脂肪蓄积,降低TG含量,其作用依赖于细胞中AMPK通路的激活。     

黄药子醇提物Caco-2细胞摄取液对HL-7702和HepG2细胞毒性研究

目的：研究黄药子醇提物Caco-2细胞摄取液对HL-7702和HepG2细胞的毒性。方法：75%乙醇回流提取得黄药子提取物,高、中、低剂量作用于Caco-2细胞,以经Caco-2细胞的摄取物作用于HL-7702细胞和HepG2细胞,进行细胞活性实验,测定生化指标ALT、AST、GSH-PX和MDA值。结果：与对照组比,高剂量组和中剂量组黄药子醇提物Caco-2细胞摄取液作用后,HL-7702细胞和HepG2细胞的存活率显著降低（P<0.01）;高剂量组黄药子醇提物Caco-2细胞摄取液作用72 h后,HL-7702细胞上清液中ALT、AST显著升高（P<0.01）;高剂量组黄药子醇提物Caco-2细胞摄取液作用48 h和72 h后, HepG2细胞上清液中ALT、AST显著升高（P<0.01）。高剂量组和中剂量组黄药子醇提物Caco-2细胞摄取液作用48 h和72 h后,HL-7702细胞和HepG2细胞上清液中MDA显著升高,GSH-PX显著降低（P<0.01）。结论：黄药子醇提物Caco-2细胞摄取液对HL-7702和HepG2细胞有毒性。     

成纤维细胞生长因子-21改善胰岛素抵抗肝细胞对葡萄糖的吸收及机制

目的建立正常人肝细胞(HL-7702)胰岛素抵抗(in-sulin resistance,IR)模型,探讨成纤维细胞生长因子-21(FGF-21)对胰岛素抵抗的改善作用及其机制。方法培养HL-7702细胞,利用高浓度胰岛素和地塞米松(dexametha-sone,DEX)诱导IR模型。GOD-POD试剂盒测定细胞葡萄糖消耗量,Western blot检测GLUT1和磷酸化ERK1/2表达水平。结果 FGF-21促进HL-7702细胞葡萄糖的消耗且呈剂量依赖性,与胰岛素联合用药提高葡萄糖消耗量。在随后IR模型实验中,FGF-21改善IR模型细胞葡萄糖消耗量。FGF-21作用24 h,GLUT1的表达量明显增高,p-ERK1/2的含量增强。当加入ERK1/2特异性抑制剂PD98059,FGF-21促ERK1/2的磷酸化作用被抑制。IR模型中,FGF-21仍能提高p-ERK1/2的含量。结论 FGF-21促进HL-7702细胞对葡萄糖的消耗,改善IR HL-7702细胞葡萄糖消耗量,提高葡萄糖转运蛋白GLUT1和ERK1/2磷酸化的表达。     

奥沙利铂诱导人白血病细胞株凋亡的研究

目的：研究第三代铂类化合物奥沙利铂对人早幼粒细胞白血病细胞株(HL—60)的影响。方法：采用MTT法检测奥沙利铂对HL—60细胞作用的时间效应和剂量效应；流式细胞仪检测细胞的DNA含量，分析细胞周期的改变；光镜和电镜观察奥沙利铂作用后细胞形态变化。结果：随着作用时间及药物浓度的增加，奥沙利铂对HL-60细胞增殖的抑制作用就越明显。0．032mmol/L奥沙利铂作用72小时，细胞生长抑制率86．5％，流式细胞仪检测HL-60细胞Q／M期细胞增多，形态学显示细胞凋亡。结论：奥沙利铂有明显抑制恶性白血病细胞生长和促进细胞凋亡的作用。     

丹参酮ⅡA对损伤肝细胞的保护作用及活化肝星状细胞的抑制作用

目的探索丹参酮ⅡA对体外培养肝细胞株HL-7702的安全使用剂量并观察丹参酮ⅡA对肿瘤坏死因子α(TNF-α)和过氧化氢(H2O2)所致体外培养肝细胞损伤的保护作用;同时探讨丹参酮ⅡA对活化肝星状细胞增殖的抑制作用。方法体外培养人肝细胞株HL-7702,加入不同浓度的丹参酮ⅡA,通过MTT比色法检测肝细胞存活率并检测培养上清液中丙氨酸转氨酶(ALT)和乳酸脱氢酶(LDH)含量的变化。建立TNF-α和H2O2所致肝细胞损伤模型,测定培养上清液中的ALT和LDH含量,同时用MTT比色法检测肝细胞存活率。体外培养大鼠肝星状细胞株HSC-T6,加入不同浓度的丹参酮ⅡA,通过MTT比色法检测肝星状细胞存活率。结果①丹参酮ⅡA在一定的剂量范围内对肝细胞无细胞毒性,超过该剂量时,其细胞毒性表现为细胞存活率下降和肝细胞合成分泌的ALT、LDH水平增高。②丹参酮ⅡA可改善TNF-α所致肝细胞存活率下降及ALT、LDH水平的增高。③丹参酮ⅡA可改善H2O2所致肝细胞存活率的下降。④丹参酮ⅡA可抑制活化肝星状细胞的增殖。结论①丹参酮ⅡA对于体外培养肝细胞株(HL-7702)的安全剂量范围为1～2μg/ml。②丹参酮ⅡA在安全剂量范围内能改善TNF-α和H2O2所致体外培养人肝细胞株的损伤。③丹参酮ⅡA在25～100μg/ml的剂量范围内可以有效抑制活化肝星状细胞的增殖。     

Astaxanthin induces mitochondria-mediated apoptosis in rat hepatocellular carcinoma CBRH-7919 cells

We designed to study the role of mitochondria in astaxanthin-induced apoptosis in hepatocellular carcinoma cells. Effect of astaxanthin on cell proliferation was studied by using methyl thiazolyl tetrazolium (MTT) in three tumor cell lines (CBRH-7919, SHZ-88 and Lewis) and normal human hepatocyte HL-7702 cell. Cell apoptosis rate, changes of mitochondrial morphology, mitochondrial transmembrane potential and electron transport chain were evaluated respectively. Expressions of B cell lymphoma/leukemia-2 (Bcl-2) and Bcl-2 associated X protein (Bax) were detected by Western blot. Results as following, astaxanthin had little effect on HL-7702 cell, however its inhibition was most pronounced in CBRH-7919 cell line with an IC?? of 39 μM. This dose of astaxanthin and CBRH-7919 cell line were chosen for further studies. Astaxanthin could induce cell apoptosis and mitochondrial membrane damage. The mitochondrial transmembrane potential and function of electron transport chain were decreased. The expression of Bcl-2 protein was down-regulated but that of Bax protein was up-regulated. In conclusion, astaxanthin showed anticancer effect by inducing cell apoptosis through the regulation of mitochondrial-dependent manner.     

Effect of hydrogen peroxide on persistent sodium current in guinea pig ventricular myocytes

AIM: To study the effect of hydrogen peroxide (H2O2) on persistent sodium current (I(Na.P)) in guinea pig ventricular myocytes. METHODS: The whole-cell, cell-attached, and inside-out patch-clamp techniques were applied on isolated ventricular myocytes from guinea pig. RESULTS: H2O2 (0.1 mmol/L, 0.5 mmol/L and 1.0 mmol/L) increased the amplitude of whole-cell I(Na.P) in a concentration-dependent manner, and glutathione (GSH 1 mmol/L) reversed the increased I(Na.P). H2O2 (1 mmol/L) increased persistent sodium channel activity in cell-attached and inside-out patches. The mean open probability was increased from control values of 0.015+/-0.004 and 0.012+/-0.003 to 0.106+/-0.011 and 0.136+/-0.010, respectively (P< 0.01 vs control). They were then decreased to 0.039+/-0.024 and 0.027+/-0.006, respectively, after the addition of 1 mmol/L GSH (P<0.01 vs H2O2). The time when open probability began to increase and reached a maximum was shorter in inside-out patches than that in cell-attached patches (4.8+/-1.0 min vs 11.5+/-3.9 min, P<0.01; 9.6+/-1.6 min vs 18.7+/-4.7 min, P<0.01). CONCLUSION: H2O2 increased the I(Na.P) of guinea pig ventricular myocytes in a concentration-dependent manner, possibly by directly oxidating the cell membrane.     

Antihypertensive effect of canrenone in a model where endogenous ouabain-like factors are present

The effect of canrenone, an antialdosterone and partial ouabain-agonist drug, was studied in rats that developed volume expansion and hypertension after renal mass reduction and excess Na+ intake (RRM-salt). The RRM-salt was characterized by: (1) increased endogenous "digitalis-like" compounds in plasma [cross reactivity with digoxin-antibodies (57.5 +/- 5.0 vs. 42.1 +/- 3.8 pg/ml, p less than 0.02); inhibition of kidney Na+, K+-ATPase activity (135 +/- 5 vs. 154 +/- 5 mumol/mg/h, p less than 0.01); and inhibition of Na+ extrusion from normal erythrocytes (5.96 +/- 0.40 vs. 7.68 +/- 0.34 mmol/L cells/h, p less than 0.01)]; (2) reduced Na+, K+-pump activity (7.34 +/- 0.29 vs. 10.88 +/- 0.41 mmol/L cells/h, p less than 0.001) and increased Na+ content (4.66 +/- .08 vs. 4.16 +/- 0.11 mmol/L cells, p less than 0.01) in erythrocytes; and (3) low plasma renin activity (2.1 +/- 0.9 vs. 12.6 +/- 1.6 ng/ml/h). Ninety minutes after the administration to RRM-salt of a single oral dose of 60 mg/kg of canrenone, the systolic blood pressure decreased by 36 +/- 4 mm Hg (mean +/- SEM). Chronic canrenone administration (60 mg/kg/day) resulted in a marked antihypertensive effect associated to a correction of volume expansion, a decrease in endogenous "digitalis-like" compounds, and a partial recovery of Na+, K+-pump activity and Na+ content in erythrocytes. Our results suggest that the antihypertensive effect in RRM-salt rats results, at least in part, from antagonism with endogenous "digitalis-like" compounds.     

（—）表没食子儿茶素没食子酸酯增强阿糖胞苷对HL—60细胞的抗肿瘤活性

AIM: To study the potentiation of anti-tumor effect induced by cytosine arabinoside (AraC) with (-)-epigallocatechin-3-gallate (EGCG). METHODS: Growth curve method and MTT assay were used to measure the cytotoxic effect of AraC alone or in combination with EGCG on HL-60 cells. Flow cytometry was used to study the cell cycle distribution of HL-60 cells. Nullification assay was used to examine whether EGCG would nullify the rescue effect of deoxycytidine (dCdR) to AraC. Western blot analysis was employed to investigate bcl-2 expression. Intracellular Ca2+ assay was evaluated. RESULTS: Inhibition of HL-60 cell proliferation induced by AraC was enhanced by EGCG, with multiplication time prolonging from 48 h to 70 h and growth saturation density decreasing from 5.78 to 5.54. The MTT results indicated that IC50 was decreased from (0.34+/-0.29) micromol/L (AraC alone) to (0.11+/-0.09) micromol/L (P<0.05) (in combination with EGCG). Cell cycle analysis indicated that AraC blocked HL-60 cells in G1 phase, inhibited cells in S phase. EGCG had no effect on cell cycle at the current concentration, but enhanced the cell arrest by AraC. Nullification assay indicated that IC50 was 0.03 micromol/L (AraC alone), increased to 0.02 mmol/L when rescued with dCdR, and finally decreased to 4.8 micromol/L when addition with EGCG. The expression of bcl-2 protein was down-regulated after treatment with AraC in combination with EGCG. The intracellular Ca2+ was increased after treatment by AraC in combination with EGCG. CONCLUSION: The combination with EGCG could enhance the anti-tumor effect of AraC on HL-60 cells.     

Sodium-dependence of the potency of inhibitors of the neuronal noradrenaline carrier in the rat vas deferens

Vasa deferentia obtained from reserpine-pretreated rats were incubated (monoamine oxidase and catechol-O-methyltransferase inhibited) in media containing various concentrations of 3H-(-)noradrenaline and Na+ and initial rates of the neuronal uptake of 3H-noradrenaline measured both in the absence and presence of uptake inhibitors after 1 min of incubation. When rates of uptake were determined at various 3H-noradrenaline (1.0-12.2 mumol/l) and two fixed Na+ concentrations (25 and 140 mmol/l), the inhibition of uptake produced by (+)amphetamine, (-)metaraminol, desipramine, nomifensine and cocaine was competitive with respect to 3H-noradrenaline at both Na+ concentrations. While the Ki for (+)amphetamine, (-)metaraminol desipramine and nomifensine increased when the Na+ concentration was lowered, that for cocaine decreased. When the Na+ concentration was varied (10-140 mmol/l) and the 3H-noradrenaline concentration held constant (1.2 mumol/l), (+)amphetamine, (-)metaraminol, nomifensine and desipramine acted as mixed-type inhibitors with respect to Na+, and the inhibition of uptake produced by these drugs was the more pronounced, the higher the Na+ concentration. On the other hand, cocaine was competitive with Na+ and the inhibition produced by this drug was the more pronounced, the lower the Na+ concentration. It is concluded that the inhibitors of neuronal uptake tested here act in dependence on the external Na+ concentration. Desipramine and nomifensine resemble alternative amine substrates in being more potent at high than at low Na+ concentrations. On the other hand, cocaine is more potent at low than at high Na+ concentrations.