阿霉素中毒性心肌细胞肌浆网摄钙功能变化

阿霉素中毒性心肌细胞肌浆网摄钙功能变化张亚臣荣烨之吕宝经赵美华杨瑾文阿霉素对心肌的毒性作用一直是阿霉素临床应用的一大障碍，以往的研究表明，阿霉素中毒性心肌病变与心肌细胞内钙调控障碍密切相关。我们通过测定细胞内游离钙浓度、肌浆网钙摄取功能及肌浆网调钙蛋...     

生长激素对阿霉素中毒大鼠心肌细胞的抗凋亡作用

目的 :观察不同剂量生长激素 (GH)对阿霉素中毒所致大鼠心肌细胞凋亡的影响。方法 :建立体外培养的大鼠心肌细胞阿霉素损伤模型 ,加入不同剂量的生长激素 ,采用流式细胞仪 (FCM)检测心肌细胞凋亡和坏死率。以 2 ,3 二苯基溴化四唑 (MTT)比色法绘制心肌细胞生长曲线。结果 :阿霉素可导致心肌细胞损伤 ,表现为心肌细胞细胞坏死和凋亡发生率增高 ;GH能促进心肌细胞增殖并降低其凋亡率 ,在 10 μg·ml- 1 至 5 0 0 μg·ml- 1 范围内 ,其抗凋亡和促增殖作用呈剂量依赖性增强。结论 :GH对阿霉素中毒所致的心肌细胞凋亡有直接的抑制作用     

欣力胶囊对阿霉素所致心肌细胞损伤的保护作用

目的观察欣力胶囊对阿霉素(ADR)中毒心肌细胞的保护作用并探讨其机制。方法采用新生SD乳鼠心肌细胞做原代培养,复制ADR损伤心肌细胞模型,测定培养上清液多项生化指标,并运用流式细胞仪检测凋亡细胞。结果ADR(终浓度为10~(-6)M)可致上清液乳酸脱氢酶(LDH)释放量增加(P<0.01),同时细胞超氧化物歧化酶(SOD)活力下降而丙二醛(MDA)含量升高(P<0.01),欣力胶囊(0.025～0.1 mg/mL)可呈浓度依赖性地降低LDH活力,增加细胞SOD活力和降低MDA含量(P<0.05或P<0.01)。流式细胞仪检测欣力胶囊能降低心肌细胞凋亡率,证实了欣力胶囊的保护作用。结论欣力胶囊能够拮抗ADR引起的自由基脂质过氧化,从而保护心肌细胞。     

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。     

牛磺酸对大鼠培养心肌细胞钙运转功能的作用

以大鼠培养心肌细胞的脂质过氧化损伤模型，采用＾４５Ｃａ示踪技术，直接进行心肌肌浆网，线粒体钙转运动功能的测定，同时观察牛磺酸对心肌过氧化损伤的保护作用，结果表明，牛磺酸能显著改善心肌肌浆网，线粒体钙转运功能，对心肌细胞具有保护作用。     

铬对培养心肌细胞的保护作用

为在细胞水平证实Ｃｒ３＋的抗心肌损伤作用，取Ｗｉｓｔａｒ乳鼠心肌加Ｃｒ３＋培养心肌细胞，用阿霉素损伤，试验前后４次描记细胞搏动，测定ＬＤＨ活性，观察细胞比活率。损伤２４小时后，各组细胞搏动频率减慢，幅度降低，时限变窄，７２小时后对照组较加Ｃｒ３＋组搏动频率减慢，幅度降低，时限变窄，并出现搏动停止，细胞部分脱落。加Ｃｒ３＋组较对照组ＬＤＨ活性增强，细胞比活率升高。结果表明Ｃｒ３＋对培养心肌细胞损伤有明显的保护作用。提示Ｃｒ３＋对心肌损伤的防治有重要意义     

原代培养的心肌细胞中毒性心肌炎模型的建立

目的 为阿霉素(ADR)中毒性心肌炎机制的研究及药物治疗提供依据.方法 取0～2日龄sD乳鼠原代心肌细胞培养,观察ADR不同浓度(0.01、0.1、1、10、100μg/ml)及不同作用时间(1μg/ml ADR作用24,48,72h)对心肌细胞存活率及培养上清液乳酸脱氢酶(LDH)、谷草转氨酶(GOT)水平的影响,并检测细胞搏动频率.结果 不同浓度ADR均可降低细胞存活率,但10 ng/ml作用后存活率明显降低,呈浓度依赖性.不同浓度ADR均可升高LDH和GOT释放量,亦呈浓度依赖性;随ADR作用时间延长,心肌细胞存活率降低,LDH和COT升高,呈时间依赖性.结论 ADR对原代培养的心肌细胞可造成氧化损伤,损伤程度与ADR浓度及作用时间呈正比.     

不同龄SHR心肌细胞内Ca^2＋及心肌细胞NE含量的变化

采用荧光探针结合计算机图像处理技术测定幼年、成年、老年ＳＨＲ心肌单细胞内游离Ｃａ＾２＋浓度，采用高血压液相色谱法测定幼年、成年、老年ＳＨＲ心肌去甲肾上腺素含量。结果显示随着年龄增加，ＳＨＲ心肌细胞内游离Ｃａ＾２＋增加，而心肌组织ＮＥ含量下降。与老年ＷＫＹ大鼠比较，老年ＳＨＲ心肌细胞内Ｃａ＾２＋含量较高，而其心肌组织ＮＥ含量却较少。     

心肌细胞中线粒体的Ca2+信号转导

心肌细胞中的Ca2+信号转导主要发生于细胞膜、肌浆网及线粒体等亚细胞结构。对前两者的研究较为透彻,而对线粒体Ca2+信号转导的过程尚存在较大争议。本文主要介绍了线粒体Ca2+信号转导的过程中Ca2+进出线粒体的几条途径,包括其功能特点、作用方式和调控机制等,并进一步分析了线粒体与其相邻肌浆网之间的Ca2+信号转导过程。     

Histidine-rich Ca binding protein: a regulator of sarcoplasmic reticulum calcium sequestration and cardiac function

Defects in the pathways that regulate cardiac sarcoplasmic reticulum (SR) calcium (Ca) cycling represent prime targets for driving the deterioration of function and progression to heart failure. We hypothesized that the histidine-rich Ca binding protein (HRC) in the SR may be involved in SR Ca cycling and that alterations in HRC levels would result in abnormal cardiac Ca homeostasis. In order to test this hypothesis, we generated transgenic mice with cardiac overexpression (3-fold) of HRC. Increased cardiac HRC levels were associated with impaired SR Ca uptake rates (35%) and attenuated cardiomyocyte Ca transient decay (38%), without alterations in peak Ca transients or SR Ca load. The depressed SR Ca sequestration was associated with attenuated rate of Ca extrusion via Na-Ca exchange. Triadin protein expression levels and L-type Ca channel current density were increased, while the channel inactivation kinetics were not altered. Impaired SR Ca uptake and delayed Ca decline rates triggered hypertrophy and compromised the heart's responses to increased stress by either hemodynamic overload or the aging process. By 18 months of age, cardiac remodeling deteriorated to congestive heart failure in transgenic mice. Collectively, these data suggest that HRC may be an integral regulatory protein involved in cardiac muscle SR Ca uptake and Ca homeostasis.     

阿托伐他汀对压力负荷引起高血压大鼠心肌肌浆网钙泵活力的影响

目的观察阿托伐他汀对压力负荷增高所致左心室肥厚(LVH)和心肌肌浆网钙泵(SERCA)活力的影响。方法雄性SD大鼠50只随机分为假手术组、腹主动脉缩窄(AAC)组、阿托伐他汀10mg/(kg·d)(Ato10mg)、阿托伐他汀30mg/(kg·d)(Ato30mg)和氨氯地平5mg/(kg·d)组,每组10只。采用腹主动脉缩窄术建立LVH动物模型,灌胃法给药4周。鼠尾容积法测量收缩压,计算左心室质量指数(LVMI),即左心室质量/体质量(LVM/BM);HE染色检测心肌细胞平均直径;无极磷酸根法测定SERCA活力;双波长荧光分光光度计检测心肌细胞内Ca2+浓度。结果与假手术组相比,AAC组收缩压、LVMI、心肌细胞平均直径、细胞内Ca2+浓度均显著升高,心肌SERCA活力(4.0±0.6)比假手术组(6.4±0.8)μmol/(mgpro.h)明显降低(均P<0.05)。与AAC组比较,阿托伐他汀30mg组及氨氯地平组均能降低大鼠收缩压、LVMI、心肌细胞平均直径和细胞内Ca2+浓度,同时能明显提高心肌SERCA活力[Ato30mg组(4.9±0.4),氨氯地平组(4.8±0.5)比AAC组(4.0±0.6)...     

Effects of low sodium perfusion on cardiac caffeine sensitivity and calcium uptake

Myocardial compartmentation of calcium was investigated in the arterially perfused rabbit interventricular septum under conditions of augmented calcium uptake. Reduction of perfusate sodium concentration (100-36 mM [Na]0) produced the expected increased active force development and an increased myocardial calcium content that was inversely proportional to [Na]0. Caffeine was used to inhibit calcium uptake by the sarcoplasmic reticulum (SR) and to stimulate SR calcium release. The diastolic tension response to caffeine was also inversely proportional to [Na]0: at [Na]0 of 139 mM, 10 mM caffeine increased diastolic tension by 20%; whereas at 36 mM [Na]0 diastolic tension increased by 205%. The increase in diastolic tension in response to caffeine was considered a reflection of increased cytosolic calcium. The increase in diastolic tension with caffeine required that reduced [Na]0 be present at the time caffeine was administered. Caffeine sensitivity (measured by an increase in diastolic tension) and active force development declined to control levels within 3 minutes after the end of a 40 minute period of low [Na]0 perfusion despite the presence of an additional 1 mmole calcium per kg dry wt in the muscle at the 3 minute mark when caffeine was added. The results indicate that low [Na]0 perfusion induces an increment in myocardial calcium content, a major fraction of which is neither related directly to contractility nor involved in the response to caffeine.     

Effects of A1 adenosine receptor stimulation on the expression of genes involved in calcium homeostasis

We investigated whether A(1) adenosine receptor stimulation affects expression of genes involved in calcium homeostasis, including sarcolemmal L-type Ca(2+) channel, Na(+)/Ca(2+) exchanger, sarcoplasmic reticulum (SR) Ca(2+)-ATPase, phospholamban, or ryanodine receptor. Three models of A(1) stimulation were used: i) an acute model, i.e. isolated perfused rat hearts treated for 120 min with 15 nM R-phenylisopropyladenosine (R-PIA), an A(1) receptor agonist; ii) a subacute model, i.e. rats treated with 1.5 mg/kg R-PIA e.v. and sacrificed after 24 h; iii) a transgenic model, i.e. mice overexpressing A(1) adenosine receptors. In all models gene expression was determined by RT-PCR, and oxalate-supported Ca(2+) uptake, representing SR Ca(2+) uptake, was measured in the crude homogenate. Significant increase in the expression of the phospholamban gene was observed in each model of A(1) stimulation, while the expression of the other four genes was not significantly modified. In the acute model, SR Ca(2+) uptake was unaffected, however in the subacute and transgenic models uptake rate was significantly reduced. In parallel experiments, hearts obtained from the subacute model demonstrated a significant reduction in irreversible tissue injury from 30 min of ischemia and 120 min of reperfusion. Increased resistance to ischemia has already been reported also in our transgenic model. In conclusion, A(1) adenosine receptor stimulation up-regulates phospholamban gene expression, which leads within 24 h to a reduced rate of SR Ca(2+) uptake. Changes in Ca(2+) homeostasis might contribute to the delayed cardioprotective effect of adenosine.     

The effect of hyperthyroidism on the sarcoplasmic reticulum and myosin ATPase of dog hearts.

Large doses of desiccated thyroid were administered to dogs for from 55 to 176 days (mean 118 days) to evaluate the effect of long-term administration upon the myocardium. An increased pulmonary vascular bed and cardiac enlargement were found in most animals. Calcium-activated myosin adenosine-triphosphatase (ATPase) activity was significantly elevated at pH values of 7.0 and below. The ATPase activity of sulfhydryl-modified myosin was also altered. However, in the presence of K⁺ and EDTA, the myosin ATPase activity was similar to that of myosin from normal dog hearts. The calcium uptake by the cardiac sarcoplasmic reticulum (CSR) (in the presence of oxalate) was significantly less than normal for the thyroid-treated dogs. The calcium content of the CSR was also less than normal for the treated dogs. The norepinephrine content of the myocardium from the thyroid-treated dogs was less than normal, but when corrected for hypertrophy was within normal limits.     

Different Effects of Adenosine and Calcium Channel Blockade on Myocardial No-Reflow after Acute Myocardial Infarction and Reperfusion

Background Adenosine and calcium channel blockers have been used in the treatment of angiographic no-reflow directly after angioplasty for acute myocardial infarction (AMI). However, their effects on tissue perfusion after AMI and reperfusion are undefined. The present study was designed to compare the effect of adenosine with that of the calcium channel blockers diltiazem and verapamil on myocardial no-reflow. Materials and methods Coronary ligation area and area of no-reflow were determined with both myocardial contrast echocardiography in vivo and histopathological evaluation in 44 Yorkshire mini-swines randomized into five study groups: ten in control, eight in adenosine-treated, nine in diltiazem-treated, nine in verapamil-treated and eight in sham-operated. An acute myocardial infarction and reperfusion model was created with 3-h occlusion of the left anterior descending coronary artery followed by 1-h reperfusion. Results Compared with the control group, adenosine significantly decreased the area of no-reflow measured with both methods from 78.5 and 82.3% to 20.7 and 21.5% of ligation area, respectively (both P < 0.01), reduced necrosis area, maintained VE-cadherin, β-catenin and γ-catenin levels in reflow myocardium (P < 0.05–0.01). Although diltiazem and verapamil also significantly decreased the area of no-reflow, they failed to significantly modify necrosis area, VE-cadherin, β-catenin and γ-catenin levels. Conclusions These findings support the concept that adenosine can reduce both structural and functional no-reflow, while calcium channel blockade can only reduce functional no-reflow.     

心房颤动患者心房肌浆网Ca~(2 )-ATP酶基因mRNA表达变化的研究

目的　研究心房颤动 (房颤 )患者Ca2 调节基因 -肌浆网Ca2 ATP酶mRNA表达的改变 ,探讨房颤时心肌细胞浆Ca2 超负荷的原因及其在房颤发生和维持中的作用。方法　 38例风心病二尖瓣狭窄接受外科手术者 ,手术时取右心房及右心耳各约 10 0mg,通过逆转录 -聚合酶链反应技术 ,以GAPDH为内参照 ,测量肌浆网Ca2 ATP酶mRNA的变化。结果　房颤者肌浆网Ca2 ATP酶mRNA较窦性心律者下调 ,而且随房颤持续时间的延长下调越明显 ,心房不同部位无差别。结论　房颤患者Ca2 ATP酶mRNA下调 ,说明肌浆网Ca2 ATP酶与房颤的发生或维持有关     

心脏收缩调节刺激对心肌细胞钙动力学的影响

目的通过计算机理论模拟心肌细胞电生理模型,在心肌动作电位(AP)绝对不应期内施加非兴奋性电刺激,观察胞内自由钙离子浓度变化及心脏收缩调节。方法在人心室细胞电生理模型的基础上,根据近年相关实验成果,通过改造以模拟衰竭心肌细胞的电生理特性。结果改造后模型的AP和胞内钙浓度变化,和临床发现非常相似。心脏收缩调节刺激大大增强了钠-钙交换器活性,在AP间期更多的钙离子经过此交换器进入胞内,逐拍提高了肌浆网内的钙浓度峰值,因而下一搏中有更多的钙离子释放到胞浆中,从而逐渐提高了细胞内的自由钙浓度,最后收敛于一个稳定值,AP的延长和胞内钙活动密切相关。结论适宜的AP绝对不应期刺激能提高肌浆网内钙的集聚,增强心肌收缩。     

Incidence and Predictors of Left Ventricular (LV) Thrombus after ST-Elevation Myocardial Infarction (STEMI) in the Holy Capital of Saudi Arabia

BackgroundPatients with acute myocardial infarction (AMI) especially those with large MI (myocardial infarction) as identified by ST elevation in multiple contiguous ECG leads or anterior MI, may suffer significant myocardial damage leading to impaired wall motion and contractility which may lead to the formation of left ventricular thrombus (LVT) in the patient. This study was aimed to establish the incidence of LV thrombus and determine the predictors associated with the formation of LV thrombus in patients with AMI.MethodsThis retrospective study was held at the only cardiothoracic centre of Makkah, which provides tertiary level cardiac services. A total of 3084 consecutive patients with acute MI between 2016 and 2019 were identified and divided into two groups i.e. group I (with LVT) and group II (without LVT). The case notes, echocardiography data and cardiac catheterization lab records were reviewed to identify patients with LV thrombus. Regression analysis was employed to evaluate the predictors responsible for the formation of LV thrombus.ResultsThe overall incidence for LV thrombus was determined as 8.4% (n = 260/3084), while in the subpopulation of pilgrims, it was 8.2% (83/1001). Mean age for patients with and without LVT was 54 ± 11 years vs 56 ± 12 years (p < 0.003), respectively. There was no significant difference between the two groups with respect to gender, diabetes, hypertension, smoking, Arabic speaking or BMI>30. Coronary thrombus aspiration was utilized in 17% vs 12% (p < 0.023) patients with LVT and without LVT, respectively. It was observed that the patients with cardiac arrest tend to develop more LVT i.e. 8.5% vs 5.2% (p < 0.033). However, LV thrombus formation was significantly associated with anterior STEMI with incidence of LVT reaching 13.4% and low ejection fraction (all MI types) i-e. 32 ± 9% vs 42 ± 11%, with p < 0.000 for both independent predictors.ConclusionsLV thrombus is a relatively common occurrence in patients with acute MI, especially those with anterior STEMI and low ejection fraction<30%. Appropriate imaging studies are required for all acute MI patients in order to ascertain the presence or absence of LV thrombus as it has major influence on further management.