RNA阵列技术检测自发性高血压大鼠肌浆网Ca2+-ATP酶和受磷蛋白基因表达

目的:探讨肌浆网Ca²⁺-ATP酶(SERCA)和受磷蛋白(PLB)在原发性高血压发病过程中的变化特点及其相互关系。方法:提取2、4、6、8、10、12不同周龄雄性自发性高血压大鼠(SHR)和正常血压大鼠(WKY)的心室肌、血管平滑肌、肝脏和肾脏组织的总RNA,共294个样品,利用高通量RNA阵列技术(RNAarray)检测SERCA和PLB基因在不同周龄SHR和WKY中mRNA表达谱改变。结果:SHR在6、8、10、12周龄血压出现显著高于同周龄WKY(均P<0.01),10、12周龄心室肌重量／体重比出现显著增加(均P<0.01),心肌和血管平滑肌SERCA的表达在4、6、8、10、12周龄出现显著高于同周龄WKY(P<0.05或P<0.01)。PLB基因表达在两组间无显著差异(P>0.05)。心肌的SERCA与PLB表达量比值在6、8、10、12周龄出现显著大于同周龄WKY(P<0.05或P<0.01),而血管平滑肌的SERCA与PLB表达量比值在4、6、8、10、12周龄出现显著大于同周龄WKY(P<0.05或P<0.01)。结论:肌浆网SERCAmRNA表达改变及SERCA与PLB比例失常是高血压发生和发展过程中重要的分子生物学机制。     

干细胞移植对慢性心功能不全兔心室肌细胞膜Na+-K+泵和肌浆网Ca2+泵活性的影响

研究经冠状动脉灌注移植自体骨髓单个核细胞（BMCs）、间充质干细胞（MSCs）和骨骼肌成肌细胞（SMs）对CHF兔CMNKA和SERCA的影响，探讨干细胞移植治疗CHF的确切机制。使用阿雩素制作兔CHF模型，经双球囊封堵主动脉根部后分别灌注BMCs、MSCs、SMs和无血清DMEM液。4周后处死动物，比较干细胞移植后CMNKA和SERCA活性变化。与对照组相比，假手术组CMNKA和SERCA活性降低（P〈0．05）。不同类型的干细胞移植后心室肌CMNKA活性均明显改善（P分别小于0．05、0．01和0．01）。干细胞移植各组SERCA有改善的趋势，但与假手术组相比，差异无统计学意义（P均大于0．05）。说明干细胞移植能够改善衰竭心室肌细胞膜Na^＋-K^＋ATP酶和肌浆网Ca^2＋ATP酶的异常，这可能是其治疗心力衰竭的重要机制之一。     

急性心肌梗死大鼠钙调蛋白的改变及卡维地洛的干预作用

目的：研究急性心肌梗死（AMI）后心力衰竭大鼠心肌钙调蛋白肌质网Ca2+-ATP酶（SERCA）和受磷蛋白（PLB)的变化及卡维地洛对其干预作用。 方法： 选取AMI术后成活的雄性SD大鼠随机分为AMI组、卡维地洛组两组。给药6周后观察血流动力学参数、心室重构指标及钙调蛋白SERCA、PLB的蛋白和mRNA表达。另设正常对照组及假手术组。 结果： AMI组左室舒张末压（LVEDP）、各心室重量均显著大于假手术组，左室内压最大收缩和舒张速率（±dp/dt）显著低于假手术组；SERCA蛋白和mRNA表达显著低于假手术组（P<0.01），PLB蛋白和mRNA表达高于假手术组（P<0.01）。卡维地洛组的LVEDP、心室重量均显著低于AMI组，±dp/dt显著高于AMI组；卡维地洛治疗使SERCA蛋白和mRNA表达明显升高（P<0.05），但未能改变PLB蛋白和mRNA水平(P>0.05）。 结论： 急性心肌梗死后心力衰竭中钙调蛋白SERCA和PLB的变化可能是心肌收缩功能失调的重要机制；卡维地洛能有效地抑制大鼠AMI后心室重构并改善血流动力学，其分子机制可能与钙调蛋白SERCA含量正常化有关。     

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。     

比索洛尔提高心力衰竭大鼠心肌SERCA2a活性

目的观察比索洛尔对心力衰竭大鼠心肌肌浆网钙ATP酶2a(SERCA2a)活性的影响。方法腹腔注射阿霉素建立大鼠心力衰竭模型。实验分为对照组、假手术组、模型组、比索洛尔组、卡托普利组和比索洛尔+卡托普利组。检测心功能指标;ELISA法检测血浆脑钠肽水平;茎环状引物实时定量PCR检测心肌miR-25-3p表达水平;Western blot检测心肌SERCA2a和受磷蛋白(PLB)表达水平;定磷法测定心肌SERCA2a活性。结果与对照组比较,模型组大鼠心功能明显减退(P0.01),血浆脑钠肽水平和心肌miR-25-3p表达水平明显升高(P0.01),SERCA2a和PLB表达水平、SERCA2a/PLB比值和SERCA2a活性明显降低(P0.01);与模型组比较,比索洛尔组、卡托普利组和比索洛尔+卡托普利组大鼠心功能明显改善(P0.01),血浆脑钠肽水平和心肌miR-25-3p表达水平明显降低(P0.01),SERCA2a和PLB表达水平明显升高(P0.01);比索洛尔组和比索洛尔+卡托普利组SERCA2a/PLB比值和SERCA2a活性明显高于模型组(P0.05)。结论比索洛尔可以下调心肌miR-25-3p表达水平,提高SERCA2a和PLB表达水平,增强SERCA2a活性。     

rAAV1-SERCA2a转染改善心力衰竭犬心功能及其机制探讨

 目的:研究重组1型腺相关病毒(rAAV1)介导的肌浆/内质网Ca2+-ATP酶2a（SERCA2a）基因转移对心力衰竭（HF）犬心功能的作用并探讨其机制。方法:采用快速右心室起搏建立比格犬的HF模型,设对照组、HF组、HF+EGFP组和HF+SERCA2a组（均n＝4）。后2组经开胸心肌内注射rAAV1-EGFP或rAAV1-SERCA2a,剂量为1×1012病毒基因组。结果:基因转移30 d后,HF+SERCA2a组超声心动图左室射血分数接近对照组,较HF组明显改善（P＜0.05),SERCA2a mRNA较HF组显著提高（P＜0.05）,SERCA2a蛋白在心肌组织中的表达显著高于HF组（P＜0.05),心肌细胞凋亡指数和基质金属蛋白酶9（MMP-9）表达较HF组显著降低（P＜0.05）。HF+EGFP组各项观察指标接近HF组。但是,受磷蛋白mRNA的水平没有改变。结论:rAAV1-SERCA2a转染上调HF犬心肌组织SERCA2a的表达,能改善心功能,抑制心室重塑;其机制可能与抑制心肌细胞凋亡、下调MMP-9表达有关。     

腺相关病毒载体介导的PLB基因反义RNA对大鼠心肌细胞肌浆网Ca2+-ATPase活性和［Ca2+］i的作用

目的：探讨腺相关病毒载体介导的磷酸受纳蛋白（PLB）反义RNA对肌浆网Ca2+-ATPase活性以及细胞内钙浓度（［Ca2+］i）的作用。 方法： 构建PLB反义RNA的重组腺相关病毒载体（rAAV-asPLB）和携带报告基因LacZ的重组腺相关病毒载体（rAAV-LacZ）。分别转染培养的大鼠心肌细胞，测定PLB mRNA和蛋白质表达，检测肌浆网Ca2+-ATPase活性和［Ca2+］i。 结果： RT-PCR和Western blotting显示，感染rAAV-asPLB的心肌细胞的PLB mRNA和蛋白质表达低于正常对照和感染rAAV-LacZ组；而Ca2+-ATPase活性大于正常对照和感染rAAV-LacZ组。激光共聚焦显微镜检测显示，静息状态时，rAAV-asPLB感染组［Ca2+］i降低；异丙肾上腺素刺激后，各组［Ca2+］i均升高，但是rAAV-asPLB感染组［Ca2+］i变化幅度大。 结论： 腺相关病毒介导的PLB反义RNA对大鼠心肌细胞PLB表达具有抑制作用，增强Ca2+-ATPase活性，降低静息状态的［Ca2+］i ，增加异丙肾上腺素刺激后［Ca2+］i 的变化幅度。     

兔膈肌肌浆网Ca2+-ATPase活性及钙离子的转运

本文分别用定磷法测定兔膈肌SR Ca 2 -APTase 活性、Fura-2 荧光法测定SR Ca 2 释放、摄取动力学和[ 3 H] -Ryanodine 与RyR 结合实验测定SR RyR 的量,分析其功能特性。 结果显示兔隔肌、心肌和骨骼肌SR Ca 2 -APTase 活性分别为70.13 ±8.25、 41.25 ±6.25 和120.17± 17.03 m mol/L pi/mg 蛋白/h1 。膈肌的SRCa 2 -APTase 活性显著高于心肌P<0.01 。但明显低于骨骼肌P<0.01; 膈肌SR Ca 2 释放量和摄取速度显著快于心肌（P<0.01）,但明显低于骨骼肌（P<0.01）;膈肌SR RyR 同[ 3 H] Ryanodine 的最大结合值（Bmax）是0.78 ±0.05pmol/mg 蛋白,其解离常数（KD）是6.93 1.13nmol/L,分别位于心肌和骨骼肌范围内。本文认为膈肌Ca 2 释放单位、SR Ca 2 -APTase 和SR Ca 2 释放摄取动力学分别具有心肌和骨骼肌的一些特征,其Ca 2 释放可能具有变构偶联和CICR 偶联两种形式,心肌型DHPR 亚型,RyR 3 和SERCA 2 a 的存在可能是膈肌ECC 依赖于细胞外Ca 2 的主要原因。     

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。     

兔角膜内皮细胞Na~+-K~+-ATP酶的电镜酶细胞化学观察

目的　探讨兔角膜内皮细胞上Na+ K+ ATP酶的分布。方法　本文采用电镜酶组化方法对兔角膜内皮细胞Na+ K+ ATP酶的分布进行观察。结果　角膜内皮细胞面向前房部分的细胞膜的Na+ K+ ATP酶活性较高。结论　内皮细胞活性的检测有利于角膜保存的研究     

Ca2+ uptake by cardiac sarcoplasmic reticulum ATPase in situ strongly depends on bound creatine kinase

The role of creatine kinase (CK) bound to sarcoplasmic reticulum (SR), in the energy supply of SR ATPase in situ, was studied in saponin-permeabilised rat ventricular fibres by loading SR at pCa 6.5 for different times and under different energy supply conditions. Release of Ca²⁺ was induced by 5 mM caffeine and the peak of relative tension (T/T _max) and the area under isometric tension curves, S _T, were measured. Taking advantage of close localisation of myofibrils and SR, free [Ca²⁺] in the fibres during the release was estimated using steady state [Ca²⁺]/tension relationship. Peak [Ca²⁺] and integral of free Ca²⁺ transients (S[Ca²⁺]_f) were then calculated. At all times, loading with 0.25 mM adenosine diphosphate, Mg²⁺ salt (MgADP) and 12 mM phosphocreatine (PCr) [when adenosine triphosphate (ATP) was generated via bound CK] was as efficient as loading with both 3.16 mM MgATP and 12 mM PCr (control conditions). However, when loading was supported by MgATP alone (3.16 mM), T/T _max was only 40% and S[Ca²⁺]_f 31% of control (P < 0.001). Under these conditions, addition of a soluble ATP-regenerating system (pyruvate kinase and phosphoenolpyruvate), did not increase loading substantially. Both S _T and S[Ca²⁺]_f were more sensitive to the loading conditions than T/T _max and peak [Ca²⁺]. The data suggest that Ca²⁺ uptake by the SR in situ depends on local ATP/ADP ratio which is effectively controlled by bound CK. Received: 23 January 1996/Received after revision: 19 April 1996/Accepted: 3 May 1996     

Unchanged protein expression of sarcoplasmic reticulum Ca2+-ATPase, phospholamban, and calsequestrin in terminally failing human myocardium

The enhanced diastolic Ca²⁺ levels observed in cardiac myocytes from patients with idiopathic dilated cardiomyopathy (DCM) may be either a consequence of functional impairment of sarcoplasmic reticulum calcium- ATPase (SERCA 2) and its regulator protein phospholamban or due to a reduction in the number of SERCA 2 proteins. As different myocardial membrane preparations may lead to different accumulation of proteins, the present study evaluated two different membrane preparations, in human failing and nonfailing myocardium for comparison of SERCA 2 activity and the protein expression of SERCA 2 and phospholamban. Crude membranes and tissue homo-genates without any centrifugation steps were prepared from human nonfailing hearts (donor hearts, NF, n=18) and terminally failing hearts (heart transplant, DCM, n=18). Calsequestrin protein expression was used as an internal control for overall protein expression. In both crude membranes and homogenates maximal SERCA 2 activity (V _max) was significantly reduced in failing heart preparations (NF crude membranes, 130±8; DCM crude membranes, 102±5 nmol ATP/mg protein per minute). In contrast, the protein expression of SERCA 2 (NF crude membranes, 488±35; DCM crude membranes, 494±42; P=0.92), phospholamban (NF crude membranes, 497±51; DCM crude membranes, 496±45; P=0.98) and calsequestrin (NF crude membranes, 109±06; DCM crude membranes, 107±08; P=0.84) was unchanged in NF and DCM hearts in both preparation methods. This was also the case when the protein expression was normalized to calsequestrin protein levels. Preparation of sarcoplasmic reticulum in crude membranes led to enhanced purification and consequently higher SERCA 2, phospholamban, and calsequestrin protein levels in crude membranes than in the homogenates, which was paralleled by an increase in SERCA 2 enzyme activity. In conclusion, the altered Ca²⁺ handling in DCM may be a consequence of reduced SERCA 2 enzyme activity and not the result of differences in protein expression of the Ca²⁺ regulating proteins SERCA 2, phospholamban, and calsequestrin in human myocardium. The present study emphasizes the importance of different myocardial membrane preparations with respect to quantitative investigations of protein expression and function. Received: 2 September 1997 / Accepted: 2 December 1997     

The role of sarcoplasmic reticulum and sarcoplasmic reticulum Ca2+-ATPase in the smooth muscle tone of the cat gastric fundus

Circular smooth muscle strips isolated from cat gastric fundus were studied in order to understand whether the sarcoplasmic reticulum (SR) and SR Ca²⁺-ATPase could play a role in the regulation of the muscle tone. Cyclopiazonic acid (CPA), a specific inhibitor of SR Ca²⁺-ATPase, caused a significant and sustained increase in muscle tone, depending on the presence of extracellular Ca²⁺. Nifedipine and cinnarizin only partially suppressed the CPA-induced tonic contraction. Bay K 8644 antagonized the relaxant effect of nifedipine in CPA-contracted fundus. Nitric-oxide-releasing agents sodium nitroprusside and 3-morpholino-sydnonimine completely suppressed the CPA-induced tonic contraction. The blockers of Ca²⁺-activated K⁺ channels, tetraethylammonium, charybdotoxin and/or apamin, decreased the contractile effect of CPA. Vanadate increased the tone but did not change significantly the effect of CPA. CPA exerted its contractile effect even when Ca²⁺ influx was triggered through the Na⁺/Ca²⁺ exchanger and the other Ca²⁺ entry pathways were blocked. Thapsigargin, another specific SR Ca²⁺-ATPase inhibitor, also increased the muscle tone. The effect of thapsigargin was completely suppressed by sodium nitroprusside and 3-morpholino-sydnonimine and partially by nifedipine. In conclusion, under conditions when the SR Ca²⁺-ATPase is inhibited, the tissue develops a strong tonic contraction and a large part of this is mediated by Ca²⁺ influx presumably via nifedipine-sensitive Ca²⁺ channels. This study suggests the important role of SR Ca²⁺-ATPase in the modulation of the muscle tone and the function of SR as a “buffer barrier” to Ca²⁺ entry in the cat gastric fundus smooth muscle. Received: 10 August 1995/Received after revision: 9 November 1995/Accepted: 10 November 1995     

The contribution of the sarcoplasmic reticulum Ca2+-transport ATPase to caffeine-induced Ca2+ transients of murine skinned skeletal muscle fibres

The present study was carried out to investigate the contribution of the Ca²⁺-transport ATPase of the sarcoplasmic reticulum (SR) to caffeine-induced Ca²⁺ release in skinned skeletal muscle fibres. Chemically skinned fibres of balb-C-mouse EDL (extensor digitorum longus) were exposed for 1 min to a free Ca²⁺ concentration of 0.36 μM to load the SR with Ca²⁺. Release of Ca²⁺ from the SR was induced by 30 mM caffeine and recorded as an isometric force transient. For every preparation a pCa/force relationship was constructed, where pCa = −log₁₀ [Ca²⁺]. In a new experimental approach, we used the pCa/force relationship to transform each force transient directly into a Ca²⁺ transient. The calculated Ca²⁺ transients were fitted by a double exponential function: Y ₀ + A ₁⋅exp (−t/t ₁) + A ₂⋅exp(t/t ₂), with A ₁ < 0 < A ₂, t ₁ < t ₂ and Y ₀, A ₁, A ₂ in micromolar. Ca²⁺ transients in the presence of the SR Ca²⁺-ATPase inhibitor cyclopiazonic acid (CPA) were compared to those obtained in the absence of the drug. We found that inhibition of the SR Ca²⁺-ATPase during caffeine-induced Ca²⁺ release causes an increase in the peak Ca²⁺ concentration in comparison to the control transients. Increasing CPA concentrations prolonged the time-to-peak in a dose-dependent manner, following a Hill curve with a half-maximal value of 6.5 ± 3 μM CPA and a Hill slope of 1.1 ± 0.2, saturating at 100 μM. The effects of CPA could be simulated by an extended three-compartment model representing the SR, the myofilament space and the external bathing solution. In terms of this model, the SR Ca²⁺-ATPase influences the Ca²⁺ gradient across the SR membrane in particular during the early stages of the Ca²⁺ transient, whereas the subsequent relaxation is governed by diffusional loss of Ca²⁺ into the bathing solution. Received: 2 February 1996/Accepted: 1 April 1996     

Effects of cytosolic Ca2+ on the Ca2+ content of the sarcoplasmic reticulum in saponin-permeabilized rat ventricular trabeculae

 Rat ventricular trabeculae were mounted for isometric tension recording, and then permeabilized with saponin. The Ca²⁺ concentration ([Ca²⁺]) within the permeabilized preparation (cytosolic [Ca²⁺]) was monitored continuously using Indo-1 and the integrals of Ca²⁺ transients resulting from brief caffeine application used as an index of the sarcoplasmic reticulum (SR) Ca²⁺ content. The relationship between SR Ca²⁺ content and cytosolic [Ca²⁺] was studied within the reported physiological range (i.e. 50–250 nmol · l^–1 Ca²⁺). Increasing cytosolic [Ca²⁺] from 50 nmol · l^–1 to 250 nmol · l^–1 increased the steady-state SR Ca²⁺ content about threefold. However, increasing [Ca²⁺] above 250 nmol · l^–1 typically resulted in spontaneous SR Ca²⁺ release, with no further increase in SR Ca²⁺ content. The SR Ca²⁺ content increased only slowly when cytosolic [Ca²⁺] was increased; it was unchanged 20 s after a rapid increase in cytosolic [Ca²⁺], but increased progressively to a new steady-state level during the following 1–2 min. In a parallel series of experiments using intact papillary muscles, increasing extracellular [Ca²⁺] (from 0.5 to 5 mmol · l^–1) significantly increased twitch tension within 20 s of the solution change. These results support previous suggestions that the SR Ca²⁺ content may increase when diastolic cytosolic [Ca²⁺] rises during inotropic interventions such as increased stimulus rate or extracellular [Ca²⁺]. However, the rate at which SR Ca²⁺ responds to changes in cytoplasmic [Ca²⁺] within the diastolic range does not appear rapid enough to explain the early potentiation of twitch tension in intact preparations after an increase in extracellular [Ca²⁺]. Received: 26 August 1997 / Accepted: 28 October 1997     

Effects of thapsigargin and cyclopiazonic acid on sarcoplasmic reticulum Ca2+ uptake,spontaneous force oscillations and myofilament Ca2+ sensitivity in skinned rat ventricular trabeculae

Thapsigargin (TG) and cyclopiazonic acid (CPA) have been reported to be potent inhibitors of the sarcoplasmic reticulum (SR) Ca²⁺ uptake in isolated SR vesicles and cells. We have examined the effect of TG and CPA on (1) the Ca²⁺ uptake by the SR in saponin-skinned rat ventricular trabeculae, using the amplitude of the caffeine-induced contraction to estimate the Ca²⁺ content loaded into the SR, (2) the spontaneous Ca²⁺ oscillations at pCa 6.6 using force oscillation as the indicator, and (3) the myofilament Ca²⁺ sensitivity in Triton X-100-treated preparations. Inhibition of Ca²⁺ loading by TG and CPA increased with time of exposure to the inhibitor over 18–24 min. TG and CPA produced half inhibition of Ca²⁺ loading at 34.9 and 35.7 μM respectively, when 18–24 min were allowed for diffusion. The spontaneous force oscillations were more sensitive to the inhibitors: 10 μM TG and 30 μM CPA both abolished the oscillations in this time. The myofilament Ca²⁺ sensitivity was not affected by 10 and 300 μM TG or CPA. The results show that the concentrations of TG and CPA necessary to inhibit the SR Ca²⁺ uptake of skinned ventricular trabeculae are much higher than the reported values for single intact myocytes. One reason for this may be slow diffusion of the inhibitors into the multicellular trabecula preparation. Received: 28 July 1995/Received after revision: 11 December 1995/Accepted: 18 December 1995