感染性休克大鼠心肌肌浆网摄钙功能的变化

本工作观察大鼠感染性休克不同阶段心肌肌浆网(SR)摄钙功能的改变。结果表明在休克早期心肌SR的钙摄取功能尚无明显变化;SR Ca~(2+)-ATP酶活性抑制和钙摄取量降低出现在感染性休克的晚期阶段,可能是心功能障碍的重要原因。     

糖尿病大鼠心肌磷酸受纳蛋白基因表达和肌浆网 Ca2+-ATPase活性的变化

目的：观察糖尿病(DM)大鼠心肌磷酸受纳蛋白（PLB）基因表达和肌浆网 Ca2+-ATPase活性的变化及其与心功能的关系。方法:复制糖尿病大鼠模型，分别于4、6、8周后对糖尿病组和对照组进行左心室血流动力学检测，测定心肌PLB mRNA转录水平以及蛋白表达水平变化，检测心肌肌浆网 Ca2+-ATPase活性。结果:糖尿病大鼠心肌PLB mRNA转录和蛋白表达水平4周时与正常大鼠无明显差异，6周时和8周时明显高于正常大鼠；肌浆网 Ca2+-ATPase活性4周时无明显改变，6周时和8周时明显低于正常大鼠；糖尿病大鼠4周时LVSP、LVEDP、±dp/dtmax与正常大鼠无明显差异，6周、8周时LVSP、±dp/dtmax显著降低，LVEDP显著升高。结论：糖尿病大鼠心肌PLB表达水平升高，肌浆网 Ca2+-ATPase活性降低，引起心功能下降。     

糖尿病大鼠心肌磷酸兰苯蛋白含量的改变

目的：观察糖尿病大鼠心肌肌质网Ca²⁺-ATP酶（SERCA）和磷酸兰苯蛋白（PLB）的改变。方法：复制糖尿病大鼠模型,12周后比较糖尿病大鼠和对照组大鼠的心脏/体重比,并以Western印迹法测定两组大鼠心肌组织SERCA和PLB含量。结果：糖尿病大鼠心脏/体重比显著大于对照组（P<0.01）;虽然SERCA在两组间无显著差异,但是糖尿病大鼠心肌内PLB表达以及PLB/SERCA比值显著高于对照组（P<0.05）。结论：糖尿病可造成大鼠心肌内PLB含量和PLB/SERCA比值增高。     

压力负荷性左室肥厚大鼠心肌钠钙交换体和肌浆网钙泵的表达

目的 观察压力负荷性左室肥厚大鼠心功能异常及心肌钠钙交换体(NCX)和肌浆网钙泵(SERCA2a)的表达变化.方法 缩窄大鼠腹主动脉制备压力负荷性心肌肥厚模型,测定在体血流动力学及左室重量指数(LVWI),用RT-PCR和Western blot法检测左室组织NCX及SERCA2a的表达.结果 与假手术组相比,模型大鼠左室收缩压(LVSP)及左室舒张末压(LVEDP)均显著升高(P<0.01,P<0.001);左室重量指数显著增加(P<0.001)及左室NCX mRNA表达上调(P相似文献   

钙调蛋白与肥厚心肌的心律失常

钙调蛋白(calmodulin,CaM)是广泛存在于真核生物体内的一种多功能蛋白质,是Ca2+在体内的一个重要受体。CaM通过Ca2+/CaM依赖的钙调神经磷酸酶及CaMKⅡ,调节心肌细胞肥大相关基因的表达;通过心肌细胞膜上钙通道的磷酸化,造成钙超载,进而诱导心肌肥厚及肥厚心肌心律失常的发生。钙调蛋白在肥厚心肌心律失常机制的阐述,对指导临床治疗和开发新的、更有效的药物具有重要的意义。     

长期甲状腺素刺激对大鼠心肌Ca /钙调蛋白依赖性蛋白激酶Ⅱ的影响

目的: 通过观察长期甲状腺素刺激对心肌Ca²⁺/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKII)的影响,探讨CaMKII是否参与甲亢性心脏病的发生发展。方法: 将20只SD大鼠随机分为甲状腺素刺激组和对照组,每组各10只。以0.2 mg·kg^-1·d^-1的剂量腹腔注射甲状腺素或等体积生理盐水3个月(每次给药前称体重),造模后3个月处死大鼠。以心重(HW)、心重与体重之比(HW/BW)、左心室重与体重之比(LVW/BW)及心肌细胞直径大小反映心肌肥厚;以心肌血管周围胶原面积(PVCA)/血管腔面积(VA)的比值反映心肌纤维化。用实时定量RT-PCR和Western blotting分别从mRNA水平和蛋白表达水平反映CaMKII的变化。结果: 造模3个月后与对照组相比,甲状腺素刺激组的HW/BW、LVW/BW、心肌细胞直径大小和心肌纤维化程度(PVCA/VA)均明显高于对照组,分别是对照组的1.87、1.84、2.15和1.94倍,差异均显著(P<0.05,P<0.01);甲状腺素刺激组心肌细胞中CaMKII mRNA表达水平、蛋白含量与对照组相比均降低,分别是对照组的40%和79%,但CaMKII的活性较对照组增加1.58倍,其差异均显著(P<0.05)。结论: 长期甲状腺素刺激诱导大鼠心肌肥厚模型中,甲状腺素降低心肌CaMKII的表达,但心肌CaMKII的活性增加,CaMKII可能参与甲状腺素诱导的甲亢性心脏病的发生发展。     

维生素D_3诱导的钙超载大鼠心肌肌浆网功能变化

目的 :观察钙超载大鼠心肌肌浆网 (SR )功能的变化。方法 :腹腔注射维生素D3和nicotine灌胃复制大鼠心肌钙超载模型。差速离心制备心肌肌浆网 ,微孔过滤技术测定SR的钙释放与钙摄取 ,放射配基法测定SRryanodine受体结合能力。结果 :钙超载大鼠心肌钙含量比对照组高 32 4% (P <0 0 1) ,心肌SR钙摄取和钙释放分别低 6 4%和 40 % (P <0 0 1)。心肌SRCa2 -ATP酶活性低 6 5 % (P <0 0 1)。SR特异 [3H]-ryanodine结合的最大值Bmax低 5 1% (P <0 0 1)。结论 :钙超载大鼠心肌SR功能下降。     

腺相关病毒介导的PLB基因反义RNA对糖尿病大鼠心肌肌浆网

目的: 构建磷酸受纳蛋白(PLB)反义RNA腺相关病毒载体(rAAV-asPLB),建立糖尿病(DM)大鼠模型。直接心肌注射rAAV-asPLB,观察其对DM大鼠心肌PLB基因转录和蛋白表达的影响,以及对心肌肌浆网Ca²⁺-ATPase活性的作用。方法: 利用质粒辅助重组腺相关病毒系统试剂盒构建rAAV-asPLB。腹腔注射链脲佐菌素(STZ)诱导DM大鼠模型,将实验动物分为4组:正常组、DM组、盐水组和rAAV-asPLB组。盐水或rAAV-asPLB注射后6周,RT-PCR检测心肌PLB mRNA转录;Western blotting检测PLB蛋白表达水平;检测心肌肌浆网Ca²⁺-ATPase活性。结果: (1)成功构建rAAV-asPLB,诱导出DM大鼠模型。(2)DM组和盐水组PLB mRNA水平均高于正常组;rAAV-asPLB组PLB mRNA水平较DM组和盐水组明显降低。 (3)DM组和盐水组PLB 蛋白水平均高于正常组;rAAV-asPLB组PLB 蛋白水平较DM组和盐水组明显降低。(4)肌浆网Ca²⁺-ATPase活性在DM组和盐水组中较正常组明显降低,而rAAV-asPLB组较DM组和盐水组升高。结论: rAAV-asPLB抑制DM大鼠心肌PLB表达,增强Ca²⁺-ATPase活性。     

神经肽Y诱导大鼠心肌细胞内游离钙重分布研究

目的: 观察神经肽Y(NPY)对大鼠心肌细胞胞浆钙浓度和肌浆网(SR)内钙含量的影响。方法: 用100 nmol·L^-1 NPY刺激Sprague-Dawley乳鼠心肌细胞24 h, 用荧光染料Fluo-4 AM负载胞浆钙, 记录静息状态下心肌细胞胞浆钙浓度，并用咖啡因诱导的胞浆钙瞬变幅度来反映肌浆网内总钙负荷；用荧光染料Fluo-5N AM 直接标记心肌细胞肌浆网内游离钙离子。所有钙影像均由Leica SP2激光共聚焦显微镜记录。结果: 100 nmol·L^-1 NPY刺激24 h后，心肌细胞胞浆游离钙浓度明显高于对照组（P<0.05）；心肌细胞肌浆网内游离钙含量明显低于对照组 (P<0.01)；咖啡因诱导下钙瞬变幅度也低于对照组。结论: 24 h NPY刺激可导致心肌细胞内游离钙出现空间分布的变化，即胞浆钙浓度增高而肌浆网内钙负荷减少。     

Thyroid control of contractile function and calcium handling in neonatal rat heart

Newborn rats were rendered hyperthyroid (daily subcutaneous injections of L-triiodothyronine, 10 g 100 g^–1 body weight) or hypothyroid (0.05% 6-n-propyl-2-thiouracil in drinking water to nursing mothers) during the first 3 weeks of postnatal life. Compared with the euthyroid group, hyperthyroidism resulted in: (1) cardiac enlargement with right ventricular preponderance, (2) increased cardiac contractile function, (3) increased Ca²⁺ uptake by the sarcoplasmic reticulum (SR), (4) decreased sensitivity to the negative inotropic effect of verapamil and (5) greater inhibition of contractile function by ryanodine. Hypothyroidism generally resulted in opposite changes. The data suggest that the development of the heart and its contractile function during early postnatal life depends on the plasma level of thyroid hormones. In particular, the relative contribution of the SR and sarcolemmal Ca²⁺ transport to the control of cardiac contractility seems to be markedly affected by altered thyroid states. The postnatal maturation of the SR function is accelerated in hyperthyroidism but retarded in hypothyroidism. Consequently, hyperthyroid hearts appear to be less dependent and hypothyroid ones more dependent on trans-sarcolemmal Ca²⁺ fluxes when compared with age-matched euthyroid animals.     

舒张性心力衰竭兔Ca2+调控蛋白mRNA和蛋白质的表达

目的:探讨心肌细胞内Ca²⁺超负荷以及Ca²⁺调控蛋白在舒张性心力衰竭(DHF)发生中的作用。方法:采用RT-PCR和Westernblot技术测定实验兔Ca²⁺调控蛋白mRNA和蛋白质表达的变化。结果:⑴DHF兔心肌细胞内Ca²⁺含量显著高于假手术组(P＜0.01);⑵DHF兔SRCa²⁺-ATPase活性明显低于假手术组(P＜0.01);⑶DHF兔SRCa²⁺-ATPase和细胞膜L型Ca²⁺通道的mRNA水平明显低于假手术组(P＜0.05),而磷酸受纳蛋白、兰尼碱受体和肌集钙蛋白的mRNA转录无明显差异(P＞0.05);⑷DHF兔SRCa²⁺-ATPase的蛋白质表达明显低于假手术组(P＜0.05);磷酸受纳蛋白的相对含量与假手术组无明显差异(P＞0.05)。结论:SRCa²⁺-ATPase的mRNA和蛋白质表达减低以及细胞膜L型Ca²⁺通道mRNA转录减低是导致心肌细胞内Ca²⁺超负荷及DHF发生的重要因素。     

Effects of K-201 on the calcium pump and calcium release channel of rat skeletal muscle

The benzothiazepine derivative K-201 has been suggested as a potential therapeutic agent due to its antiarrhythmogenic action. To understand how the drug alters calcium release from the sarcoplasmic reticulum (SR), we investigated its effects on the SR calcium channel and calcium pump by single channel electrophysiology, whole-cell confocal microscopy, and ATPase activity measurements on control and post-myocardial infarcted (PMI) rat skeletal muscle. In bilayers, K-201 induced two subconductance states corresponding to ∼24% (S₁) and ∼13% (S₂) of the maximum conductance. Dependence of event frequency and of time spent in S₁ and S₂ on the drug concentration was biphasic both in control and in PMI rats, with a maximum at 50 μM. At this concentration, the channel spends 26 ± 4% and 24 ± 4%, respectively, of the total time in these subconductance states at positive potentials, while no subconductances are observed at negative potentials. K-201 altered the frequency of elementary calcium release events: spark frequency decreased from 0.039 ± 0.001 to 0.023 ± 0.001 s⁻¹ sarcomere⁻¹, while the frequency of embers increased from 0.011 ± 0.001 to 0.023 ± 0.001 s⁻¹ sarcomere⁻¹. Embers with different amplitude levels were observed after the addition of the drug. K-201 inhibited the Ca²⁺ ATPase characterized by IC_50,contr = 119 ± 21 μM and n _Hill,contr = 1.84 ± 0.48 for control and IC_50,PMI = 122 ± 18 μM and n _Hill,PMI = 1.97 ± 0.24 for PMI animals. These results suggest that although K-201 would increase the appearance of subconductance states, the overall calcium release is reduced by the drug. In addition, the effect of K-201 is identical on calcium release channels from control and PMI rats.     

Impaired calcium homeostasis in aged hippocampal neurons

Development of neurodegenerative diseases such as Alzheimer's and Parkinson's disease is strongly age-associated. The impairment of calcium homeostasis is considered to be a key pathological event leading to neuronal dysfunction and cell death. However, the exact impact of aging on calcium homeostasis in neurons remains largely unknown. In the present work we have investigated intracellular calcium levels in cultured primary hippocampal neurons from young (2 months) and aged (24 months) rat brains. Upon stimulation with glutamate or hydrogen peroxide aged neurons in comparison to young neurons demonstrated an increased vulnerability to these disease-related toxins. Measurement of calpain activity using Western blot analysis showed a significant increase in basal activity of calpains in aged neurons. The observed increase of calpain activity was correlated with elevated protein levels of μ-calpain. Ca²⁺-imaging experiments performed on living individual neurons using the dye calcium green demonstrated a twofold increase in intracellular calcium concentration in aged neurons as compared to young neurons. The observed changes of intracellular calcium in aged neurons might play a role in their increased vulnerability to neurodegeneration.     

Calcium transport proteins in the nonfailing and failing heart: gene expression and function

In heart failure alterations of intracellular Ca²⁺ handling are thought to be a major reason for impaired contraction and relaxation. Peak Ca²⁺ transients are reduced, resting Ca²⁺ levels elevated, and the time course of diastolic Ca²⁺ decline is markedly prolonged in failing hearts. The proteins of the sarcoplasmic reticulum and the sarcolemmal Na⁺/Ca²⁺ exchanger are the most important tools for Ca²⁺ homeostasis in the cardiomyocyte, and their molecular cloning has allowed prediction of structure/function analysis. The investigation of function and gene expression of these proteins in failing myocardium has been an area of intensive research in recent years in order to provide a more detailed understanding of the pathophysiology of heart failure. Quantitative changes in expression of the sarcoplasmic reticulum Ca²⁺-ATPase, the ryanodine receptor, and the Na⁺/Ca²⁺ exchanger with correlations to functional alterations have been reported both in experimental animal models and in the human failing heart. However, in human heart failure these findings are currently the subject of a lively discussion because observations have apparently been in part contradictory. This review discusses the proteins involved in myocardial Ca²⁺ handling and describes the current state of research on expressional and functional alterations and their potential implication in the pathomechanism of heart failure.Abbreviations ANF Atrial natriuretic factor - PLN Phospholamban - RyR Ryanodine receptor - SR Sarcoplasmic reticulum - SERCA Sarco(endo)plasmic reticulum Ca²⁺-ATPase     

Role of sarco/endoplasmic reticulum calcium content and calcium ATPase activity in the control of cell growth and proliferation

Ca²⁺, the main second messenger, is central to the regulation of cellular growth. There is increasing evidence that cellular growth and proliferation are supported by a continuous store-operated Ca²⁺ influx. By controlling store refilling, the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) also controls store-operated calcium entry and, thus, cell growth. In this review, we discuss data showing the involvement of SERCA in the regulation of proliferation and hypertrophy. First, we describe the Ca²⁺-related signaling pathways involved in cell growth. Then, we present evidence that SERCA controls proliferation of differentiated cells and hypertrophic growth of cardiomyocytes, and discuss the role of SERCA isoforms. Last, we consider the potential therapeutic applications of increasing SERCA activity for the treatment of cardiovascular diseases and of modulating SERCA and SR content for the treatment of cancer.