ROLE OF OXYGEN IN MYOCARDIAL REOXYGENATION INJURY AND THE PROTECTIVE EFFECT OF SHENG MAI SAN

The mechanism of myocardial reoxygenation injury and Sheng Mai San's (生脉散) protection on the myocardium were studied by the Langendorff isolated perfused heart system. After the anoxic perfusion for 40 minutes, the myocardial ultrastructure was abnormally changed. The myocardial succinate dehydrogenase (SDH), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities were decreased. After anoxia for 35 minutes and reoxygenation for 5 minutes, the myocardial ultrastructural changes were more prominant. The activities of SDH, SOD and GSH-Px were further depressed with the level of end product of lipid peroxidation, malondialdehyde (MDA), being increased. When Sheng Mai San was added into the perfusate during the anoxia and reoxygenation processes, myocardial ultrastructure was seen to be improved, The SDH, SOD, and GSH-Px activities were elevated with the level of MDA being reduced, Thus, it can be concluded that the oxygen free radicals and the lipid peroxidation play critical roles in the process of reoxygenation injury on the myocardium and that Sheng Mai San possesses protective effect on the myocardial injury through improving myocardial ultrastructure and metabolism.     

EFFECT OF HIGENAMINE ON ACTION POTENTIAL OF PURKINJE''''S CELLS AND VENTRICULAR MYOCARDIAL CELLS IN DOGS

Action potentials of isolated Purkinje's cellsin dogs and the electrophysiological actions ofdl-demethylcoclaurine(DMC)on dog Purkinje'scells were studied by glass microelectrodes.The effects of DMC on the action potentialof Purkinje's cells were:(1)increase of am-plitude of the plateau phase;(2)enhancementof repolarization of phase 3 and shortening ofAPD;(3)DMC(1×10~(-7)g/ml)caused a shorten-ing of APD without any significant change ofthe ERP,while DMC(1×10~(-6)g/ml)caused shor-tening of both APD and ERP;(4)DMC(10~(-6)g/ml)increased the slope of phase 4,decreasedthe threshold of depolarization,and increasedthe automaticity of the Purkinje's cells;(5)theaction of DMC on the Purkinje's cells was onlypartially blocked by tetraodontoxin and vera-pamil.The above results suggest that:(1)LMCenhances the influx of both Na~+ and Ca~(++) inslow channel;(2)relatively high concentrationsof DMC may induce tachyarrhythmias,whilelower concentrations may prevent the arrhyth-mias;(3)DMC may increase the ventricular ratein patients with complete heart block abovebundle of His but not in blockages below Hisbundle;(4)there is a slight increase of ERF bylow concentration of DMC DMC thus appearssafer than isopreterenol in the treatment ofbradyarrhythmias.     

STUDIES ON HAWTHORN AND ITS ACTIVE PRINCIPLE Ⅱ.EFFECTS ON CULTURED RAT HEART CELLS DEPRIVED OF OXYGEN AND GLUCOSE

Vitexin rhamnoside(VR)is one of the activeprinciples extracted from the leaves of hawthorn(Crataegus pinnatifida Bge.vat.major N.E.Br.).Theaction of VR on the performance of cultured ratheart cells and rat heart ceils deprived of oxygen andglucose was observed.Results showed no evidentchanges in the heart beat rate,rhythm,range orstrength of heart ceil clusters before and after me-dication.VR did not counter the actions of ouabainand aconitine at cellular levels.Results also demon-strated VR's protective action on cultured heart cellsdeprived of oxygen and glucose.     

PROTECTIVE EFFECT OF INSULIN ON ISOLATED RAT HEARTS

The protective effect of preoperative intravenous infusion of high doses of insulin (2U/100gm) was studied in isolated rat heart models, using modified Langendorff apparatus. Fifteen rat hearts were equally divided into three groups: Group Ⅰ(control group) received glucose and potassium within 60 min. prior to the onset of operation. Group Ⅱ (insulin group) was administered with glucose, insulin and potassium(GIK)within 60 min. before operation, whereas Group Ⅲ(insulin cardioplegia group)was treated with the same amount of GIK Preoperatively as well as an addition of insulin (100U/L) to the cardioplegia. All the rat hearts were subjected to a 30-min. period of ischemia. Coronary effluent, lactic dehydrogenase (LDH) of coronary effluent, myocardial water content, histochemistry and ultrastructure of myocardium were studied. After reperfusion, the amount of coronary effluent was 2.84±0.79 ml/min/100gm in Group Ⅱ, 1.32±0.45 ml/min/100gm in Group Ⅰ and 1.72±1.03 ml/min/100gm in Group Ⅲ, respectively, (Group Ⅱ vs Group Ⅰ or Ⅲ p<0.05), LDH was significantly lower in Group Ⅱ (4.48±1.24 U/L) than in Group Ⅰ (25.16±8.96 U/L) (P<0.01) and in Group Ⅲ (17.8±12.2 U/L) (P<0.05), but no significant difference could be seen between Group Ⅰ and Group Ⅲ. Myocardial water content was 71.5±1.21% in Group Ⅱ and 78.57±3.14% in Group Ⅰ (p<0. 01), whereas it was 75.42±3.28% in Group Ⅲ(vs Group Ⅰ and Ⅱ p>0.05).Histochemical succinodehydrogenase (SDH) reaction was graded 0 to 1 in Group Ⅱ and 2 to 3 in Group Ⅰ and Ⅲ (p<0.01). Group Ⅱ showed nearly normal myocardial ultrastructure with increased glycogen stores, while Groups Ⅰ and Ⅲ revealed local myofibrillary disorganization. disrupted mitochondria and Pronounced depletion of glycogen storages. These results prove that the Protective effect of preoperative application of high doses of insulin together with glucose and potassium on isolated rat hearts is definitely superior to the use of glucose and potassium alone. These findings also suggest that addition of insulin to cardioplegia is ineffective and even harmful to the ischemic myocardium.     

THE LOCALIZATION OF ADRENOMEDULLIN IN RAT KIDNEY TISSUE AND ITS INHIBITORY EFFECT ON THE GROWTH OF CULTURED RAT MESANGIAL CELLS

Adrenomedullin（AM），anovelhypotensivepeptideoriginallyisolatedfromhumanpheochromocytoma（１），wassynthesizedinvarioustissues（２，３）．Thecalcitoninreceptor－likereceptor／receptoractivity－modifyingpro－tein－２complexapparentlyservesasafunctionala－     

PROTECTIVE EFFECT OF MELATONIN ON NEURAL CELLS AGAINST THE CYTOTOXICITY OF OXYRADICALS

Objective. To investigate the exact mechanism of melatonin to prohibit the apoptosis of neural cells induced by various kinds of cytotoxic agents. Methods. We used the methods of phase contrast microscopy, MTT assay and hoechst dye staining to check this mechanism in SKNSH and U251 cell lines. Results. Both 2mmol/L H2O2 and 0. 5 μmol/L amyloid β- protein (Aβ) induce these two cell lines die via apoptosis. Either melatonin or glutathione can significantly protect both cell lines. The protective effect of 10 μmol/L melatonin is as same as that of 60μmol/L glutathione. Conclusion. Melatonin can partly inhibit the cytotoxicity of H2O2 and Aβ through its role as a free radical scavenger.     

EFFECT OF ELECTROACUPUNCTURE ON THE OXYGEN METABOLISM OF MYOCARDIUM DURING MYOCARDIAL ISCHEMIC INJURY

Treatment of coronary heart disease,anginapectoris,acute and chronic myocardial infarc-tion with acupuncture has been reported withcertain beneficial effect.Experiment on animalsdemonstrated that needling at Neiguan acupoint(P 6) could obviously improve cardiac hemokine-tics and contractility of myocardium and reducethe ischemic area of myocardium inducedby ligation of the coronary artery.A recenttheory has demostrated that the decrease in thevolume of blood flow in the coronary artery and     

STUDY ON THE MECHANISM AND EFFECTS OF GLY-TYR-NH2 AND GLY-TYR-LYS ON RAT LUTEAL CELLS IN VITRO

The action of Gly-Tyr-NH2,(GY-NH2) and Gly-Tyr-LYS(GYK) on ^125I-LH binding,cAMP accumulation and progesterone production was investigated.Incubation of rat luteal cells for 2.5h with GH-NH2 and GYK at dosage of 0.2mmol/L caused a significant inhibition of basal and gonadotropin-stimulated steroidogenesis.GYNH2 and GYK were also foumnd to reduce cAMP formation in response to hCG.The activity of adenylate cyclase of luteal cells was inhibitd by 0.2mmol/LGY-NH2 and GYK.GY-NH2 and GYK at a concentration of 0.2mmol/L were not found to have an inhibitory effect on 8Br-cAMP-stimulated progesterone production.GY-NH2 and GYK did not affect ^125I-LH binding to LH receptors on the luteal cellsurface.These results suggest that GY-NH2 and GYK inhibit steroidogenesis at the step of gonadotropin-stimulated c AMP for mation in luteal cells.Adenylate cyclase in luteal cells was also inhibited.     

EFFECT OF GOSSYPOL ACETIC ACID ON CHROMOSOME ABERRATIONS AND ANEUPLOIDIES IN OOCYTES AND ZYGOTES OF MICE

It was reported that gossypol acetic acid could effectively inhibit th~ implantation in ratA. This finding indicated that gossypol acet/c acid might also be used as a female contraceptive. The Present study further investigated the genetic effect of gossypol acetic     

THE EFFECT OF ALL-TRANS RETINOIC ACID ON GAP JUNCTIONAL INTERCELLULARCOMMUNICATION AND CONNEXIN 43 GENE EXPRESSION IN GLIOMA CELLS

INTRODUCTIONGapjunctionsaresmallaqueouschannelsthatcon－nectneighboringcellsandallowthepassageofmoleculewhosemolecularweightisnotmorethan１０００Da．Invertebrates，gapjunctionsareformedbytheconjunctionoftwoconnexons，eachconsistingofahexamerofcon－nexinpr     

硒铁对实验大鼠心肌细胞电生理的协同性影响

目的研究硒（Ｓｅ）铁（Ｆｅ）微量元素异常时心肌细胞损害的机理。方法用细胞内微电极技术分别测定饲养１４周后大鼠心肌细胞电生理的改变。结果与对照组相比，单纯高Ｆｅ组无变化；单纯低Ｓｅ组ＲＰ、ＡＰＡ降低、ＡＰＤ５０延长；低Ｓｅ并高Ｆｅ组ＲＰ、ＡＰＡ也降低，但与低Ｓｅ组相比无显著性差异，ＡＰＤ５０则明显延长。提示低Ｓｅ是心肌细胞损害的基本原因，高Ｆｅ对心肌损害有一定的协同作用     

吲哒帕胺对兔心肌缺血和再灌注损伤的保护作用的超微结构研究

应用离体兔心Ｌａｎｇｅｎｄｏｒｆ灌注动物模型，研究吲哒帕胺对心肌缺血和再灌注损伤的保护作用。１４只兔随机分为对照组和实验组。离体兔心缺血和４０ｍｉｎ后再灌注，分别取再灌注１５、３０、６０和３６０ｍｉｎ左室游离壁心肌标本，做超微结构观察。结果显示，实验组心肌超微结构改变明显小于对照组，提示吲哒帕胺对心肌缺血和再灌注损伤具有明显的保护作用。     

温针对异丙肾上腺素所致的大鼠急性心肌损伤保护的组化观察

通过预先给予温针刺激，观察浊地异丙肾上腺素（ＩＳＰ）所致的ｗｉｓｔａｒ大白鼠急性心肌损伤在４８小时的琥珀酸脱氢酶（ＳＤＨ）和乳酸氢酶（ＬＤＨ）活性变化，通过数格求积结果表明，温针能明显减轻琥珀酸脱氢酶和乳酸脱氢酶活性产物缺失面积，对ＩＳＰ所致的ｗｉｓｔａｒ大白鼠急性心肌损伤有为保护作用。     

牛磺酸对培养的心肌细胞缺氧再给氧损伤的保护作用

目的：观察牛磺酸对培养的心肌细胞损伤的影响。方法：以培养的心肌细胞为模型。在缺氧再给氧损伤细胞后,观察心肌细胞活力及搏动频率的变化,结果：牛磺酸可以提高心肌细胞的活力,提高心肌细胞的搏动频率,使心肌细胞的搏动频率明显恢复。结论：牛磺酸对缺氧再给氧损伤培养的心肌细胞有保护作用。     

锌对高脂血清培养乳鼠心肌细胞的作用

本实验研究了高脂血清和锌对培养的乳鼠心肌细胞作用。结果表明：高脂血清培养的心肌细胞搏动部位数明显减少，细胞出现明显的超微结构改变。同时心肌细胞脂质过氧化物（ＬＰＯ）明显增多，加锌则能明显增加细胞自发博动部位数，减少细胞内ＬＰＯ，并使细胞损伤明显减轻，结果提示高脂血清对培养的心肌细胞损伤与心肌细胞脂质过氧化有关，锌对高脂血清所致的心肌细胞损作胃保护作用。     

缺血预适应对心肌梗塞的保护作用及其机制

目的：观察心肌缺血预适应对心肌梗塞（ＡＭＩ）的保护作用。方法：选择２１０例ＡＭＩ病例，根据ＡＭＩ前有无心肌缺血、心绞痛将其分为两组。Ａ组有缺血预适应，Ｂ组无缺血预适应，将ＡＢ两组临床资料进行对比分析。结果：Ａ组小面积心肌梗塞的发生率明显高于Ｂ组，而左心衰竭、心律失常的发生率及病死率明显低于Ｂ组，有统计学意义。结论：心肌缺血预适应对ＡＭＩ具有保护作用，主要表现在限制梗塞的扩大，维护了梗塞后心功能，降     

心脑宁对缺血心脏及脑的保护作用

结扎大鼠左冠状动脉前降支４ｈ后，与梗塞对照组比较，心脑宁９．３ｇ·ｋｇ（－１）、１８．ｇ·ｋｇ（－１）３１．０ｇ·ｋｇ（－１）使ＭＩＡ％分别减少２７．１％、５９．７％和６３．６％；使血清中ＣＫ和ＬＤＨ分别减少３７．５％、４３．１％和５１．２％及５６．０％、５１．３％和６６．１％，作用明显优于阳性对照药生脉饮，统计学有显著性差异。生脉饮６．４９．ｋｇ（－１）使ＭＩＡ％减少３０．０％，ＣＫ和ＬＤＨ分别减少１５．６％及２７．４％。但心脑宁不如普萘洛尔作用强。心脑宁还能降低小鼠心肌乳酸含量，增加断头小鼠的呼吸次数和延长维持时间，表明心脑宁对缺氧、缺血心肌及脑均具有保护作用。     

人参皂苷Rg2对体外培养低氧心肌细胞的保护作用

目的 观察人参皂苷Rg2对低氧心肌细胞的保护作用.方法 取新生24 h的Wistar大鼠心肌细胞,体外培养4 d,随机分为正常组、模型组、人参皂苷Rg2组.人参皂苷Rg2组加入0.025 mmol/L的人参皂苷Rg2,正常组与模型组加入等量的培养液.孵育4 h后,将模型组与人参皂苷Rg2组移入37 ℃恒温密闭容器中,连续充以体积分数0.95的N2和体积分数0.05的CO2混合气体,流速20 mL/min,持续1 h,然后应用锥虫蓝染色计数存活细胞,流式细胞仪检测细胞凋亡情况,酶法测定超氧化物歧化酶(SOD)的活性及丙二醛(MDA)、一氧化氮(NO)的含量.结果 人参皂苷Rg2组与正常组心肌细胞凋亡率比模型组明显降低(F=4.75,q=6.44～8.09,P<0.05);人参皂苷Rg2组与正常组心肌细胞SOD活性、MDA和NO含量与模型组相比差异有显著性(F=5.67～13.72,q=4.35～13.68,P<0.05).结论 人参皂苷Rg2在体外有抗低氧损伤的作用,其作用机制可能是通过抑制细胞凋亡、提高抗氧化酶的活力、清除自由基而发挥作用.     

芒果甙对柔红霉素致大鼠心肌毒性细胞中铁调节蛋白表达的影响

目的:探讨铁调节蛋白1(IRP1)及铁调节蛋白2(IRP2)在芒果甙保护柔红霉素致大鼠心肌细胞毒性作用中的表达及其意义。方法:以4μmol/L柔红霉素单用或联合应用25～200μmol/L芒果甙为处理因素作用于大鼠心肌细胞24,48h及72h,应用qRT-PCR法检测各组心肌细胞IRP1、IRP2mRNA表达。结果:25～200μmol/L芒果甙模型组在干预24h后IRP1、IRP2表达水平较柔红霉素组(4μmol/L)降低,干预48,72h后,二者表达较柔红霉素组升高。结论:芒果甙能改变柔红霉素致大鼠心肌毒细胞中铁调节蛋白的表达水平,对细胞内铁代谢产生影响。