银杏叶提取物对低氧复氧、H2O2和谷氨酸损伤时谷氨酸引起的大鼠星形胶质细胞［Ca2+］i变化的影响

目的研究银杏叶提取物对低氧复氧、H₂O₂和L-谷氨酸损伤时谷氨酸升高大鼠星形胶质细胞［Ca²⁺］_i的影响。方法钙荧光探针Fluo-3/AM标记胞浆内游离钙离子，激光扫描共聚焦显微镜测定［Ca²⁺］_i的变化。结果 在低氧复氧、H₂O₂以及高浓度的L-谷氨酸损伤后，外源性谷氨酸（27 μmol·L^-1）均不能引起培养乳大鼠星形胶质细胞正常的［Ca²⁺］_i升高，反而使［Ca²⁺］_i分别降低(3.3±1.6)%，(81±11)%和(81±7)%；损伤前预先给予GbE（10 mg·L^-1）不能明显改善星形胶质细胞的谷氨酸反应，但预先给予GbE（100 mg·L^-1）后，27 μmol·L^-1谷氨酸可使损伤的星形胶质细胞［Ca²⁺］_i分别升高(135±98)%，(117±93)%和(89±36)%。结论低氧复氧、H₂O₂以及高浓度的L-谷氨酸均能损伤星形胶质细胞的谷氨酸反应，影响神经细胞与胶质细胞的双向交流。GbE能明显逆转不同损伤后谷氨酸诱导星形胶质细胞［Ca²⁺］_i的异常变化，使星形胶质细胞在不同损伤时能维持正常功能，该作用可能与GbE的脑保护作用有关。     

M3受体与大鼠缺血性心肌细胞凋亡关系的研究M3受体与大鼠缺血性心肌细胞凋亡关系的研究

目的观察M₃受体对大鼠缺血性心肌细胞凋亡的作用及其机制。方法结扎大鼠左冠状动脉前降支建立急性心肌缺血模型,给予M₃受体激动剂胆碱或阻断剂4DAMP进行干预,观察M₃受体对其的影响。结果缺血前15 min iv胆碱10 mg·kg^-1可提高血清超氧化物歧化酶(SOD)活力,降低丙二醛(MDA)含量,减少凋亡细胞的数量(P<0.01),并可增加Bcl-2表达,减少Fas表达。预先5 min iv 4DAMP 0.12 mg·kg^-1阻断心肌M₃受体可逆转胆碱的作用。结论激动M₃受体对结扎大鼠冠状动脉诱导的心肌损伤有保护作用,其机制可能与调节Bcl-2和Fas表达从而抑制心肌细胞凋亡有关。     

毒毛旋花子苷元对豚鼠心室肌细胞内钙浓度的影响

观察毒毛旋花子苷元(strophanthidin, Str)对分离豚鼠心室肌细胞内游离钙浓度(［Ca²⁺］_i)的影响。酶解分离豚鼠心室肌细胞, 用Fluo 3-AM负载, 激光共聚焦显微镜法测定单个豚鼠心室肌细胞［Ca²⁺］_i的荧光密度。Str可浓度依赖性地升高［Ca²⁺］_i, Str (10 μmol·L^-1)在［Ca²⁺］_i升高达峰值时, 可使细胞挛缩, 而Str (1和10 nmol·L^-1)对细胞形态无影响。TTX、 尼索地平或升高细胞外钙可影响Str (1和100 nmol·L^-1)对［Ca²⁺］_i的升高作用,而对Str (10 μmol·L^-1)无明显影响。在外液中加入ryanodine或去除细胞外钙, 则3个检测浓度的Str升高［Ca²⁺］_i作用均被明显抑制。在无K⁺、 无Na⁺液中, 10 μmol·L^-1 Str升高［Ca²⁺］_i的作用减弱, 而Str (1和100 nmol·L^-1)升高［Ca²⁺］_i的作用无明显影响。加入TTX、 尼索地平或增加细胞外的钙离子浓度, 则3个检测浓度Str的作用均受到影响。提示低浓度Str对［Ca²⁺］_i的升高作用与抑制Na⁺、K⁺-ATP酶活性无关, 而与促进L-型钙通道和TTX敏感性钠通道的“slip-mode”钙电导有关; 高浓度Str升高［Ca²⁺］_i的作用则是抑制Na⁺、K⁺-ATP酶的结果。此外, Str对［Ca²⁺］_i的升高作用还与直接作用于ryanodine受体促进内钙释放有关。     

人参皂苷Rg1对H2O2诱导的HaCaT细胞氧化损伤保护作用研究

目的 观察人参皂苷Rg₁对H₂O₂诱导的HaCaT细胞氧化损伤保护作用,并探讨其机制。方法 体外培养HaCaT细胞, H₂O₂诱导细胞建立氧化应激损伤模型,分为空白组、H₂O₂损伤组、人参皂苷Rg₁保护组。细胞增殖与毒性检测试剂盒(CCK-8)检测细胞存活率,Hochest染色法检测细胞凋亡情况,活性氧检测试剂盒测定细胞活性氧(ROS)水平,Western blot检测细胞中caspase-3、caspase-6、caspase-8、GAPDH蛋白表达。结果 H₂O₂诱导HaCaT细胞半数抑制浓度为100 μg?mL^-1;与H₂O₂损伤组比较,5、10和15mg?L^-1人参皂苷Rg₁预处理后,HaCaT细胞存活率明显升高(P<0.05),细胞核皱缩损伤状态明显改善,细胞凋亡数量显著减少。同时,人参皂苷Rg₁预处理可显著降低HaCaT细胞ROS水平,下调凋亡相关标志蛋白-活化型caspase-3、caspase-6、caspase-8蛋白表达水平。结论 人参皂苷Rg₁对H₂O₂诱导的HaCaT细胞氧化应激损伤具有一定的保护作用,其机制可能与增强细胞清除自由基能力及抑制凋亡相关。     

过氧化氢诱导牛主动脉内皮细胞损伤和胞内Ca2+升高及钙拮抗剂的抑制作用

为探讨缺氧/缺血过程中自由基损伤与钙超载的关系,观察了过氧化氢(H₂O₂)诱导培养牛主动脉内皮细胞(BAEC)的损伤和胞内游离钙([Ca²⁺]i)的变化。结果表明,H₂O₂可剂量、时间依赖地诱导BAEC活性下降(MTT值下降),脂质过氧化产物丙二醛(MDA)生成显著增加,同时伴有[Ca²⁺]i迅速显著升高。钙拮抗剂硝苯地平可剂量依赖地抑制H₂O₂引起的[Ca²⁺]i升高;同时能显著升高BAEC的MTT值,降低MDA生成,有效对抗H₂O₂诱导的BAEC损伤。提示,H₂O₂诱导内皮损伤可能与升高[Ca²⁺]i有关,Ca²⁺超载可能是活性氧致损伤的途径之一。钙拮抗剂对活性氧损伤具有一定保护作用。     

蚓激酶的心肌保护作用及机制

目的研究蚓激酶对心肌缺血的保护作用，并进一步探讨其可能机制。方法采用结扎大鼠左冠状动脉前降支制备急性心肌缺血模型，观察蚓激酶对心肌缺血的保护作用；应用全细胞膜片钳和激光扫描共聚焦技术，研究蚓激酶对L-型钙电流(I_Ca-L)和细胞内游离钙离子浓度的影响。结果蚓激酶80，40和20 mg·kg^-1剂量组均可缩小心肌梗死面积。膜片钳研究结果表明，当刺激电压为+10 mV时，10和50 μmol·L^-1蚓激酶使I_Ca-L降低共聚焦结果显示，在静息状态下，10 μmol·L^-1蚓激酶对［Ca²⁺］_i无明显影响；但10 μmol·L^-1蚓激酶对60 mmol·L^-1 KCl诱导的［Ca²⁺］_i升高却有明显抑制作用，并且在整个实验过程中(240 s)并未出现明显的峰值。结论蚓激酶对大鼠心肌缺血具有保护作用，其机制可能与抑制I_Ca-L及下调［Ca²⁺］_i有关。     

Bcl-2蛋白对环匹阿尼酸诱导CHO细胞凋亡的保护作用

Hoechst 33258染色和DNA电泳分析揭示了内质网钙泵抑制剂环匹阿尼酸(CPA)呈浓度依赖性地诱导CHO细胞凋亡, 表现出染色体固缩和DNA片断形成的典型特征. Bcl-2的过度表达对CPA诱导的CHO细胞凋亡具有保护作用. 采用Fura-2技术测定细胞内游离钙浓度(［Ca²⁺］_i)变化，观察到Bcl-2对CPA触发的细胞Ca²⁺库Ca²⁺释放无任何影响. 结果表明Bcl-2蛋白对CPA诱导的CHO细胞凋亡的保护作用不是通过抑制CPA诱导的Ca²⁺释放，而是作用于［Ca²⁺］_i升高的下游途径.     

神经肽DGAVP和Org2766对神经细胞内游离Ca2+的影响

运用Ca²⁺指示剂Fura-2作为细胞内钙离子的荧光探针,利用AR—CM—MIC阳离子测定系统,检测了分离的神经细胞内游离钙及其变化,并观测了DGAVP和Org2766对蛋白质合成抑制剂茴香霉素(ANI)引起细胞内钙离子浓度([Ca²⁺]_i)变化的影响。结果表明茴香霉素可使[Ca²⁺]_i显著升高,且有量效关系;DGAVP本身并不引起[Ca²⁺]_i发生显著变化,但适当剂量的DGAVP可显著对抗一定剂量范围内ANI升高[Ca²⁺]_i的作用,提示DGAVP对抗ANI的蛋白质合成抑制效应可能是通过拮抗ANI升高[Ca²⁺]_i这一途径实现的,另一神经肽Org2766则可能不是通过这一机制发生作用。从细胞内Ca²⁺的角度看,这两种肽的作用机理显然是不同的。     

没药甾酮对H2O2损伤PC12细胞的保护作用

探讨没药甾酮(guggulsterone)对氧化应激损伤PC12细胞的保护作用。以过氧化氢(hydrogen peroxide，H₂O₂)损伤PC12细胞为氧化应激损伤模型， 维生素E为对照， 采用四甲基偶氮唑蓝［3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide，MTT］法检测细胞增殖状况； 试剂盒检测乳酸脱氢酶(lactate dehydrogenase,LDH)及一氧化氮(nitric oxide，NO)的释放； DCFH法和Fura 2-AM法检测细胞内活性氧(reactive oxygen species，ROS)和Ca²⁺的含量； 碘化丙啶(propidium iodide，PI)染色流式细胞术(flow cytometry，FCM)检测细胞凋亡； 罗丹明123(rhodamine 123，Rh 123)染色FCM检测细胞线粒体膜电位(mitochondrial membrane protential，MMP)。结果表明， 没药甾酮(0.1～10 μmol·L^-1)可使200 μmol·L^-1 H₂O₂作用24 h后的PC12细胞生长抑制率下降； 细胞外LDH和NO， 细胞内ROS和Ca²⁺含量降低； 明显抑制200 μmol·L^-1 H₂O₂作用12 h后诱导的PC12细胞凋亡和线粒体膜电位降低作用，没药甾酮(0.1～10 μmol·L^-1)使细胞凋亡率由24.3%下降至18.4%、 15.9%、 11.8%。实验结果表明, 没药甾酮对氧化应激损伤PC12细胞具有保护作用， 其机制可能为降低细胞内ROS含量， 进而抑制LDH和NO释放， 降低细胞内Ca²⁺含量， 升高线粒体膜电位,减少细胞凋亡。     

比较不同类型抗抑郁剂对新生大鼠神经细胞内游离Ca2+浓度的影响

The ability of antidepressant drugs to increase the concentration of intracellular Ca²⁺(［Ca²⁺］_i) was examined in dispersed brain cells from neonatal rat cortex and hippocampus using the Ca²⁺ sensitive fluorescent indicator Fura-2. Desipramine (DIM 0.1-1.0 mmol·L^-1) increased ［Ca²⁺］_i in a concentration-dependent manner. DIM (1.0 mmol·L^-1) and fluoxetine (1.0 mmol·L^-1) induced ［Ca²⁺］
_i increases were not altered by the absence of external Ca²⁺ or by the presence of nimodipine (10 μmol·L^-1). Pretreatment with neomycin (10 mmol·L^-1), an inhibitor of inositol 1,4,5-trisphosphate production, significantly inhibited DIM-induced ［Ca²⁺］_i increase but could not effectively inhibit fluoxetine-induced ［Ca²⁺］_i increase. Pretreatment with dantrolene (0.05 mmol·L^-1), an exhaustor of Ca²⁺ store, inhibited fluoxetineinduced ［Ca²⁺］_i increase, suggesting that DIM and fluoxetine provoke intracellular Ca²⁺ mobilization. In addition, fluoxetine-induced ［Ca²⁺］_i increase was about 1.5 times higher than that induced by DIM at the same concentration (0.4 mmol·L^-1). Moclobemide, an inhibitor of monoamine oxidase A, did not affect ［Ca²⁺］_i. It is concluded that DIM and fluoxetine may be Ca²⁺ mobilizing agents.     

Effect of dopamine receptor 1 on apoptosis of cultured neonatal rat cardiomyocytes in simulated ischaemia/reperfusion

Dopamine receptors exist in many tissues, including rat cardiac tissue. However, the physiological importance of dopamine receptors in the homeostatic regulation of cardiac function is unclear. In this study, a model of ischaemia/reperfusion was established by culturing primary neonatal rat cardiomyocytes in ischaemia-mimetic solution for 2 hr, followed by incubation in normal culture medium for 24 hr. Lactate dehydrogenase activity, superoxide dismutase activity and malondialdehyde content were determined colorimetrically with a spectrophotometer. Apoptotic cell death was assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling staining and flow cytometry, and morphological alterations were observed with transmission electron microscopy. The intracellular free calcium concentration ([Ca2+]i) was measured by confocal laser scanning microscopy. Finally, the expression of dopamine receptor 1 (DR1), caspase-3, -8 and -9, Fas, Fas ligand and Bcl-2 and the release of cytochrome c were analysed by Western blot. The results showed that DR1 expression was increased markedly during ischaemia/reperfusion. Treatment with 10 microM SKF-38393 (DR1 agonist) significantly increased lactate dehydrogenase activity, decreased superoxide dismutase activity and increased malondialdehyde content in the culture medium. The DR1 agonist promoted the release of cytochrome c, accumulation of [Ca2+]i, and apoptosis induced by ischaemia/reperfusion. Furthermore, SKF-38393 up-regulated the expression of caspase-3, -8 and -9, Fas and Fas ligand, and down-regulated Bcl-2 expression. In contrast, 10 microM SCH-23390 (DR1 antagonist) had no significant effects on the above indicators. In conclusion, DR1 activation is involved in the apoptosis of cultured neonatal rat cardiomyocytes in simulated ischaemia/reperfusion through the mitochondrial and death receptor pathways.     

细胞内游离钙与柯萨奇病毒B3诱导的大鼠培养心肌细胞凋亡

目的 探讨（Ｃａ＾２＋）ｉ在柯萨奇病毒（ＣＶ）Ｂ３诱导心肌培养细胞凋亡中的作用。方法 ＤＮＡ裂点检测法（３′－末端标记）及扫描电镜检测细胞凋亡。Ｆｌｕｏ３－ＡＭ负载心肌细胞,共聚劁业微镜观察（Ｃａ＾２＋）ｉ荧光强度变化。结果：感染２４ｈ,心肌细胞内ＣＶＢ３的浓度达峰值,感染１０ｈ未见凋亡的心肌细胞,１７,２４和３６ｈ凋亡细胞分别为５％,６０％和９０％,感染１７ｈ心肌（Ｃａ＾２＋）ｉ浓度达峰值,电镜     

Cytosolic calcium increase in coronary endothelial cells after H2O2 exposure and the inhibitory effect of U78517F.

1. Cytosolic calcium concentrations ([Ca2+]i) were determined with fura-2 on both resting (unstimulated) and A23187-stimulated coronary endothelial cells following injury by hydrogen peroxide (H2O2). 2. Treatment of cells with H2O2 (10(-4) M) caused an increase in the resting [Ca2+]i, which reached a maximum of five fold after 3 h. 3. The increase in resting [Ca2+]i was significantly attenuated by treatment with U78517F, a potent inhibitor of lipid peroxidation, at a concentration of 10(-6) M or greater. Catalase (50 u ml-1) also markedly inhibited the H2O2-induced rise in [Ca2+]i. Pretreatment with verapamil (10(-5) M), nifedipine (10(-6) M) or diltiazem (10(-5) M) had no effect on the increase in [Ca2+]i following addition of H2O2. 4. A23187 produced a transient increase in [Ca2+]i followed by a sustained plateau. The initial peak and plateau phase responses to A23187 were augmented by H2O2. This augmentation of [Ca2+]i was suppressed by U78517F or catalase but not by Ca-entry blockers. 5. Thus, it is likely that lipid peroxidation plays a critical role in the sustained increase in [Ca2+]i that occurs following treatment with H2O2 and that this continues in the presence of agonists which stimulate the endothelium. Voltage-gated Ca2+ channels do not seem to be involved in the genesis of cellular damage associated with sustained large increases in [Ca2+]i.     

Pharmacologic modulation of the immune interaction between cytotoxic lymphocytes and ventricular myocytes

Numerous studies have demonstrated that immune effector mechanisms cause serious heart diseases, among which are heart transplant rejection, myocarditis, and the resulting dilated cardiomyopathy, as well as Chagas' disease. Whereas different effectors of the immune system can affect cardiac function, this review primarily focuses on the immune damage caused by cytotoxic T lymphocytes. The immune attack staged by cytotoxic T lymphocytes is carried out by one of two distinct modes of lymphocytotoxicity: (a) secretion of lytic granules containing the pore-forming protein perforin and a family of serine proteases (i.e., granzymes) and (b) interaction between the lymphocyte Fas ligand and the target cell Fas receptor. Ventricular myocytes challenged by the immune system sustain diverse intracellular changes, among which the rise in intracellular calcium ([Ca2+]i) constitutes an important contributor to myocyte dysfunction. Hence, this [Ca2+]i rise, which does not necessarily result in apoptosis, can affect cardiac function directly and indirectly. Importantly, the final outcomes of these perturbations vary markedly and depend on intracellular circumstances such as the magnitude of the absolute rise in [Ca2+]i and its temporal and spatial determinants, the metabolic status of the myocyte, as well as a fine balance between pro-apoptotic and anti-apoptotic factors. In view of the central role of [Ca2+]i rise in immune-mediated myocyte dysfunction and possibly cell death, this review addresses three topics related to the immune assault on the heart: (a) [Ca2+]i rise in affected myocytes; (b) the source for the [Ca2+]i rise; and (c) pharmacologic modification of the immune-mediated [Ca2+]i rise.     

ELECTRICALLY INDUCED INTRACELLULAR Ca2+ TRANSIENT IN SINGLE VENTRICULAR MYOCYTES: A USEFUL PARAMETER FOR THE STUDY OF CARDIAC DRUGS

1. Fluorescent Ca2+ indicators, such as fura-2/AM and calcium green-1, have become one of the most popular tools for measuring intracellular calcium ([Ca2+]i). 2. Electrical stimulation triggers a cascade of events in the cardiac muscle, which results in a [Ca2+]i transient and, eventually, contraction. The events that occur in electrically induced cardiac myocytes mimic the normal physiological events in vivo. 3. The electrically induced [Ca2+]i transient represents influx of Ca2+ from outside and mobilization of Ca2+ from the intracellular store and is directly related to contraction. Thus, it is more important to determine the electrically induced [Ca2+]i transient than [Ca2+]i. The [Ca2+]i transient can be easily measured with the spectrofluorescence method using fura 2/AM as the Ca2+ indicator in a single ventricular myocyte preparation. 4. We made use of the results of studies on carbachol, tetrandrine and cardiotoxin to illustrate the usefulness of the electrically induced [Ca2+]i transient in the study of actions of cardiac drugs.     

Dopamine D2 receptor stimulation inhibits angiotensin II-induced hypertrophy in cultured neonatal rat ventricular myocytes

1. Myocardial hypertrophy is a common pathological change that accompanies cardiovascular disease. Dopamine D2 receptors have been demonstrated in cardiovascular tissues. However, the pathophysiological involvement of D2 receptors in myocardial hypertrophy is unclear. Therefore, the effects of the D2 receptor agonist bromocriptine and the D2 receptor antagonist haloperidol on angiotensin (Ang) II- or endothelin (ET)-1-induced hypertrophy of cultured neonatal rat ventricular myocytes were investigated in the present study. 2. Protein content and protein synthesis, determined by examining [(3)H]-leucine uptake, were used as estimates of cardiomyocyte hypertrophy. The expression of D2 receptor protein in neonatal rat ventricular myocytes was determined using western blotting. Changes in [Ca(2+)](i) in cardiomyocytes were observed by laser scanning confocal microscopy. 3. Angiotensin II and ET-1, both at 10 nmol/L, induced myocyte hypertrophy, as demonstrated by increased protein content and synthesis, [Ca(2+)](i) levels, protein kinase C (PKC) activity and phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase and mitogen-activated protein kinase (MAPK) p38 (p38). Concomitant treatment of cells with 10 nmol/L AngII plus 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy, MAPK phosphorylation and PKC activity in the membrane, as well as [Ca(2+)](i) signalling pathways, compared with the effects of AngII alone. In addition, 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy induced by 10 nmol/L ET-1. However, pretreatment with haloperidol (10 micromol/L) had no significant effects on cardiomyocyte hypertrophy induced by either AngII or ET-1. 4. In conclusion, D2 receptor stimulation inhibits AngII-induced hypertrophy of cultured neonatal rat ventricular myocytes via inhibition of MAPK, PKC and [Ca(2+)](i) signalling pathways.     

心肌肥厚对κ阿片受体介导的信号通路受损

目的：分离正常及慢性缺氧性右心肥厚的心室肌细胞,观察细胞内[Ca^2 ]i及细胞内pHi对心肌κ－阿片受体激动后的反应。方法：以fura-2和BCECF分别为[Ca^2 ]i和pHi的指示剂,用光谱荧光法测定电刺激引起的细胞内[Ca^2 ]i瞬变及pHi。结果：κ阿片受体选择性激动剂U50,488H可降低电刺激引起的[Ca^2 ]i瞬变和增加pHi,该作用是由蛋白激酶C（PKC）所介导。在肥厚的心室肌细胞,U50,488H的上述作用显著减弱。与此相对应,PKC的激动剂PMA引起的[Ca^2 ]i瞬变降低和pHi的增加作用在肥厚的心室肌细胞亦消失。用NH4C1法观察Na^ -H^ 交我器的功能显示其在肥厚的心室肌细胞无明显改变。结论：心肌肥厚时κ－阿片受体介导的信号通路受损,受损部位发生在PKC与效应器之间。     

腺苷A1受体激活在钙调磷酸酶信号通路上对异丙肾上腺素诱导的心肌细胞肥大的抑制作用

目的观察腺苷A1受体激活在钙调磷酸酶(CaN)通路上对异丙肾上腺素(Iso)诱导的心肌细胞肥大的抑制作用及机制。方法体外培养大鼠乳鼠心肌细胞,以Iso 10μmol.L-1诱导心肌细胞肥大,观察腺苷A1受体激动剂R(-)-N6-(2-phenylIsopropyl)adenosine(R-PIA)1μmol.L-1对其作用,进一步探讨钙调神经磷酸酶特异性抑制剂环孢菌素A(CSA)1μmol.L-1、PKA抑制剂cAMP三乙胺盐(RP-cAMPS)1μmol.L-1、百日咳毒素(PTX)5 mg.L-1存在时,腺苷A1受体的激活对心肌细胞肥大的影响。通过Lowry法测心肌细胞蛋白含量;RT-PCR法检测心肌细胞心钠素(ANP)的mRNA表达;Western blot法测心肌细胞CaN的相对表达水平;以Fluo-3/AM为荧光探针,共聚焦显微镜下测量心肌细胞[Ca2+]i瞬变。结果 10μmol.L-1 Iso可以诱导心肌细胞肥大,腺苷A1受体激动剂R-PIA可以使其蛋白含量降低、ANP的mRNA表达减少、CaN相对表达降低、[Ca2+]i荧光强度减小,CSA、RP-cAMPS有类似抑制作用,PTX预处理的情况下,R-PIA对Iso诱导的心肌肥大的抑制作用消失。结论腺苷A1受体可以通过钙调磷酸酶通路抑制Iso诱导的心肌肥大,其机制与降低细胞内[Ca2+]i浓度及CaN表达有关。     

Tanshinone IIA protects cardiac myocytes against oxidative stress-triggered damage and apoptosis

Tanshinone IIA (tan), a derivative of phenanthrenequinone, is one of the key components of Salvia miltiorrhiza Bunge. Previous reports showed that tan inhibited the apoptosis of cultured PC12 cells induced by serum withdrawal or ethanol. However, whether tan has a cardioprotective effect against apoptosis remains unknown. In this study, we investigated the effects of tan on cardiac myocyte apoptosis induced both by in vitro incubation of neonatal rat ventricular myocytes with H(2)O(2) and by in vivo occlusion followed by reperfusion of the left anterior descending coronary artery in adult rats. In vitro, as revealed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay, treatment with tan prior to H(2)O(2) exposure significantly increased cell viability. Tan also markedly inhibited H(2)O(2)-induced cardiomyocyte apoptosis, as detected by ladder-pattern fragmentation of genomic DNA, chromatin condensation, and hypodioloid DNA content. In vivo, tan significantly inhibited ischemia/reperfusion-induced cardiomyocyte apoptosis by attenuating morphological changes and reducing the percentage of terminal transferase dUTP nick end-labeling (TUNEL)-positive myocytes and caspase-3 cleavage. These effects of tan were associated with an increased ratio of Bcl-2 to Bax protein in cardiomyocytes, an elevation of serum superoxide dismutase (SOD) activity and a decrease in serum malondialdehyde (MDA) level. Taken together, these data for the first time provide convincing evidence that tan protects cardiac myocytes against oxidative stress-induced apoptosis. The in vivo protection is mediated by increased scavenging of oxygen free radicals, prevention of lipid peroxidation and upregulation of the Bcl-2/Bax ratio.