Dilated cardiomyopathy and heart failure caused by a mutation in phospholamban

Molecular etiologies of heart failure, an emerging cardiovascular epidemic affecting 4.7 million Americans and costing 17.8 billion health-care dollars annually, remain poorly understood. Here we report that an inherited human dilated cardiomyopathy with refractory congestive heart failure is caused by a dominant Arg --> Cys missense mutation at residue 9 (R9C) in phospholamban (PLN), a transmembrane phosphoprotein that inhibits the cardiac sarcoplasmic reticular Ca2+-adenosine triphosphatase (SERCA2a) pump. Transgenic PLN(R9C) mice recapitulated human heart failure with premature death. Cellular and biochemical studies revealed that, unlike wild-type PLN, PLN(R9C) did not directly inhibit SERCA2a. Rather, PLN(R9C) trapped protein kinase A (PKA), which blocked PKA-mediated phosphorylation of wild-type PLN and in turn delayed decay of calcium transients in myocytes. These results indicate that myocellular calcium dysregulation can initiate human heart failure-a finding that may lead to therapeutic opportunities.     

Voltage-independent calcium release in heart muscle

The Ca2+ that activates contraction in heart muscle is regulated as in skeletal muscle by processes that depend on voltage and intracellular Ca2+ and involve a positive feedback system. How the initial electrical signal is amplified in heart muscle has remained controversial, however. Analogous protein structures from skeletal muscle and heart muscle have been identified physiologically and sequenced; these include the Ca2+ channel of the sarcolemma and the Ca2+ release channel of the sarcoplasmic reticulum. Although the parallels found in cardiac and skeletal muscles have provoked valuable experiments in both tissues, separation of the effects of voltage and intracellular Ca2+ on sarcoplasmic reticulum Ca2+ release in heart muscle has been imperfect. With the use of caged Ca2+ and flash photolysis in voltage-clamped heart myocytes, effects of membrane potential in heart muscle cells on Ca2+ release from intracellular stores have been studied. Unlike the response in skeletal muscle, voltage across the sarcolemma of heart muscle does not affect the release of Ca2+ from the sarcoplasmic reticulum, suggesting that other regulatory processes are needed to control Ca2(+)-induced Ca2+ release.     

Increased activity of calcium leak channels in myotubes of Duchenne human and mdx mouse origin

Elevated free Ca2+ concentrations found in adult dystrophic muscle fibers result in enhanced protein degradation. Since the difference in concentrations may reflect differences in entry, Ca2+ leak channels in cultures of normal and Duchenne human myotubes, and normal and mdx murine myotubes, have been identified and characterized. The open probability of leak channels is markedly increased in dystrophic myotubes. Other channel properties, such as mean open times, single channel conductance, ion selectivity, and behavior in the presence of pharmacological agents, were similar among myotube types. Compared to the Ca2+ concentrations in normal human and normal mouse myotubes, intracellular resting free Ca2+ concentrations ([Ca2+]i) in myotubes of Duchenne and mdx origin were significantly higher at a time when dystrophin is first expressed in normal tissue. Taken together, these findings suggest that the increased open probability of Ca2+ leak channels contributes to the elevated free intracellular Ca2+ concentration in Duchenne human and mdx mouse myotubes.     

慢性充血性心力衰竭患者血清心肌肌钙蛋白I和C-反应蛋白的变化

目的:探讨慢性充血性心力衰竭(CHF)患者心功能改善前后血清心肌肌钙蛋白I(cTnI)及C-反应蛋白(CRP)的变化及意义。方法:37例慢性充血性心力衰竭(NYHA分级Ⅲ~Ⅳ级)患者分别于入院d2和心功能改善至Ⅰ~Ⅱ级后抽取血清作cTnI、CRP测定。结果:治疗前患者血清cTnI阳性率54.1%,CRP超正常范围占78.4%。经治疗心功能改善后患者血清cTnI阳性率21.6%(P<0.01),CRP超正常范围占35.1%(P<0.01)。结论:部分慢性充血性心力衰竭患者心功能恶化时存在心肌损伤或坏死,此过程随心功能改善而改变,部分可能与其它因素有关。     

Sodium-calcium exchange in heart: membrane currents and changes in [Ca2+]i

Recordings have been made of changes in intracellular calcium ion concentration ([Ca2+]i) that can be attributed to the operation of an electrogenic, voltage-dependent sodium-calcium (Na-Ca) exchanger in mammalian heart cells. Guinea pig ventricular myocytes under voltage clamp were perfused internally with fura-2, a fluorescent Ca2+-indicator, and changes in [Ca2+]i and membrane current that resulted from Na-Ca exchange were identified through the use of various organic channel blockers and impermeant ions. Depolarization of cells elicited slow increases in [Ca2+]i, with the maximum increase depending on internal [Na+], external [Ca2+], and membrane voltage. Repolarization was associated with net Ca2+ efflux and a decline in the inward current that developed instantaneously upon repolarization. The relation between [Ca2+]i and current was linear, and the slope was made steeper by hyperpolarization.     

Effect of Hypoxia on Ca^2＋ Concentration in Broiler＇s Cardiac Muscle Cells

The purpose of this research was to study the effect of hypoxia on the Ca^2＋ concentration in broiler＇s cardiac muscle cells （CMCs）. The concentration of Ca^2＋ in the CMC was observed using a laser scanning confocal microscope （LSCM）. The results showed that hypoxia could significantly increase intracellular Ca^2＋（normal oxygen, 99.3 ＋_ 13.1; hypoxia, 129.4 ＋_ 24.3, P 〈 0.01） in CMCs. The Ca^2＋ antagonist （nifedipine, verapamil） could significantly restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia （CMC： hypoxia ＋ verapamil, 100.9± 28.2; hypoxia ＋ nifedipine, 107.6± 27.7; P 〈 0.01）. The results showed hypoxia could increase intracellular Ca^2＋ concentration of CMC, and the Ca^2＋ antagonist could restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia.     

Atrial natriuretic peptide elevation in congestive heart failure in the human

A sensitive radioimmunoassay for atrial natriuretic peptide was used to examine the relation between circulating atrial natriuretic peptide and cardiac filling pressure in normal human subjects, in patients with cardiovascular disease and normal cardiac filling pressure, and in patients with cardiovascular disease and elevated cardiac filling pressure with and without congestive heart failure. The present studies establish a normal range for atrial natriuretic peptide in normal human subjects. These studies also establish that elevated cardiac filling pressure is associated with increased circulating concentrations of atrial natriuretic peptide and that congestive heart failure is not characterized by a deficiency in atrial natriuretic peptide, but with its elevation.     

Molecular basis for the influence of muscle length on myocardial performance

According to Starling's law of the heart, the force of contraction during the ejection of blood is a function of the end-diastolic volume. To seek the molecular explanation of this effect, a study was made of the effects of length on Ca2+ sensitivity during tension development by isolated demembranated cardiac muscle in which the cardiac form of troponin C was substituted with skeletal troponin C. The results of troponin C exchange were compared at sarcomere lengths of 1.9 and 2.4 micrometers. Enhancement of the myocardial performance at the stretched length was greatly suppressed with the skeletal troponin C compared with the cardiac troponin C. Thus the troponin C subunit of the troponin complex that regulates the activation of actin filaments has intrinsic molecular properties that influence the length-induced autoregulation of myocardial performance and may be a basis for Starling's law of the heart.     

桃小食心虫鱼尼丁受体基因克隆及表达模式分析

【目的】二酰胺类杀虫剂的作用靶标鱼尼丁受体（ryanodine receptor, RyR）是目前所知的最大的离子通道蛋白,该受体可控制细胞内Ca²⁺的释放,对细胞内Ca²⁺的稳定起着关键作用。克隆获得桃小食心虫鱼尼丁受体基因（CsRyR）全长序列,进一步解析该基因在桃小食心虫(Carposina sasakii)各发育阶段的表达模式。【方法】通过同源序列比对的方法,利用cDNA末端快速扩增技术（RACE）获得该基因的全长cDNA序列;应用生物信息学软件对该基因的开放阅读框、编码的氨基酸序列、功能结构域等信息进行预测分析,并基于最大似然法构建该基因与其他昆虫相关基因序列的系统发育树,明确其系统进化关系。分别提取桃小食心虫各发育阶段RNA,以GAPDH为内参基因,应用RT-qPCR技术,解析CsRyR在桃小食心虫各发育阶段（卵、幼虫、蛹和成虫）的表达模式。【结果】桃小食心虫CsRyR的cDNA全序列长度为15 766 bp,开放阅读框15 405 bp,编码5 134个氨基酸。氨基酸序列比对结果显示,CsRyR与脊椎动物RyRs的一致度分别为45%-47%;与秀丽隐杆线虫（Caenorhabditis elegans）RyR的一致度也为46%。在昆虫RyRs中,与鳞翅目一致度为91%-94%,与同翅目、双翅目昆虫一致度均为79%。系统发育树显示该基因编码的蛋白质与鳞翅目夜蛾科和螟蛾科害虫RyRs亲缘关系最近。结构域分析结果显示,CsRyR具有RyR的典型结构域,如位于C-末端的6个跨膜结构域（AA 4 467-5 029）、释放Ca²⁺的通道形成基序GVRAGGGIGD、Ca²⁺结合位点EF-hand和3个ATP结合位点GXGXXG等。二酰胺类杀虫剂可能的作用位点AA 183-290（BmRyR）,AA 4 610-4 655（DmRyR）和4 946G（PxRyR）在CsRyR中无特殊性。此外,CsRyR中存在AA 2 490- 2 496 TQAPRPG和5 131-5 134 SQAK两个基序,在其他物种中均没有发现。RT-qPCR分析结果表明,CsRyR在蛹期表达量最高,分别是1日龄卵、6日龄卵、初孵幼虫、老熟幼虫和成虫的25.19、7.73、6.48、4.74和3.58倍。【结论】克隆了CsRyR基因全长cDNA序列,证明其表达具有发育阶段特异性。     

老年心房颤动患者发生缺血性脑卒中危险因素的研究

目的:了解老年心房颤动(A f)患者发生缺血性脑卒中的危险因素。方法:采用病例对照研究对372例老年慢性A f患者的临床资料,比较发生与不发生缺血性脑卒患者的病因、心室率、年龄、性别、心衰、并发高血压病、糖尿病、心房扩大与心脏瓣膜钙化的差异。结果:A f患者中,发生与不发生缺血性脑卒患者的病因、心室率、并发高血压病、糖尿病、心房扩大、心脏瓣膜钙化的发生情况差异有非常显著性(P均<0.01),但性别、年龄、心衰、A f类型的发生情况差异均无显著性(P均>0.05)。结论:心脏瓣膜病、心室率过缓、高血压病与糖尿病是A f并缺血性脑卒中的高危因素,老年人A f并发上术疾病者容易出现缺血性脑卒中,应予临床干预。     

Cellular and subcellular heterogeneity of [Ca2+]i in single heart cells revealed by fura-2

Digital imaging of calcium indicator signals (fura-2 fluorescence) from single cardiac cells has revealed different subcellular patterns of cytoplasmic calcium ion concentration ([Ca2+]i) that are associated with different types of cellular appearance and behavior. In any population of enzymatically isolated rat heart cells, there are mechanically quiescent cells in which [Ca2+]i is spatially uniform, constant over time, and relatively low; spontaneously contracting cells, which have an increased [Ca2+]i, but in which the spatial uniformity of [Ca2+]i is interrupted periodically by spontaneous propagating waves of high [Ca2+]i; and cells that are hypercontracted (rounded up) and that have higher levels of [Ca2+]i than the other two types. The observed cellular and subcellular heterogeneity of [Ca2+]i in isolated cells indicates that experiments performed on suspensions of cells should be interpreted with caution. The spontaneous [Ca2+]i fluctuations previously observed without spatial resolution in multicellular preparations may actually be inhomogeneous at the subcellular level.     

冠心病患者血浆中分子物质和过氧化脂质水平的变化

本文检测113例冠心病患者血浆中分子物质和过氧化脂质水平,结果显示:劳累性心绞痛患者血浆中分子物质水平显著升高(P<0.05),血浆过氧化脂质水平显著降低(P<0.05);自发性心绞痛和缺血性心脏病的心力衰竭、急性心肌梗塞患者血浆中分子物质和过氧化脂质水平都显著升高(P<0.05),尤以急性心肌梗塞患者血浆中分子物质和过氧化脂质水平升高更为显著(P<0.05).本文结果表明,冠心病患者血浆中分子物质和过氧化脂质水平的变化与病变程度有关,有助于冠心病病情和预后的判断.     

曲美他嗪治疗冠心病心力衰竭近期疗效评价

目的探讨曲美他嗪治疗冠心病心力衰竭的临床疗效．方法根据治疗方案将114例冠心病心力衰竭患者分为两组,57例患者实施常规治疗为对照组,57例患者在常规治疗基础上加用曲美他嗪治疗为观察组,疗程6个月,比较两组患者的临床指标改变情况、治疗效果、药物不良反应情况．结果治疗后,两组患者左室射血分数、心输出量、左室短轴缩短率、6min步行距离、每搏输出量均显著增加,两组患者左室舒张末期内径、左室收缩末期内径、血浆B型钠尿肽均显著减小;观察组患者左室射血分数、心输出量、左室短轴缩短率、6min步行距离、每搏输出量均明显大于对照组;观察组患者左室舒张末期内径、左室收缩末期内径、血浆B型钠尿肽均明显小于对照组;观察组患者治疗总有效率明显高于对照组,差异均具有统计学意义（P〈0．05）;观察组患者药物不良反应发生率高于对照组,但差异无统计学意义（P〉0．05）．结论曲美他嗪是治疗冠心病心力衰竭的有效药物,可明显改善患者的临床指标,提高治愈率,药物不良反应少,且安全性高,值得临床推广使用．     

Cardiac sympathetic nerve activity: changes induced by ouabain and propranolol

A study of the effects of ouabain and propranolol on the spontaneous activity in the preganglionic sympathetic nerves to the cat heart showed that ouabain can produce both an inhibition and a stimulation of the spontaneous activity in sympathetic nerves. The inhibition appears to be reflex in nature and is not present when the buffer nerves are sectioned. The stimulation is correlated with the development of cardiac arrhythmias and is antagonized by propranolol.     

卡维地洛治疗老年糖尿病合并慢性心力衰竭的临床疗效和安全性观察

目的观察卡维地洛治疗老年2型糖尿病并慢性心力衰竭患者的疗效及安全性。方法老年2型糖尿病合并慢性心力衰竭患者73例随机分为卡维地洛组45例和对照组28例。对照组采用常规治疗,卡维地洛组在常规治疗基础上加服卡维地洛3.125mg,2次/d,每2周递增直至靶剂量(25mg,2次/d)或最大耐受剂量。随访12个月,比较治疗后两组患者的心率、血压、心脏功能以及血糖、胆固醇等变化,心脏事件以及药物耐受性。结果(1)随访12个月后,卡维地洛组死亡2例、中断卡维地洛2例,对照组死亡4例,均予剔除;(2)治疗后卡维地洛组(41例)心脏功能LVEDD、LVESD及LVEF较对照组(24例)改善明显(P<0.05),心率低于对照组(P<0.01),但2组心率均在正常范围内;随访期间,卡维地洛组心脏事件总发生率低于对照组(7/45vs12/28),差异有统计学意义(P<0.01);(3)两组均未发生低血糖反应、水肿及高度房室传导阻滞,两组患者的血压、血清钠、血清肌酐清除率、空腹血糖、糖化血红蛋白、低密度胆固醇等差异无统计学意义(P>0.05)。结论卡维地洛在老年糖尿病并心力衰竭患者治疗中具有良好的安全性和有效性,能改善患者的心脏功能,降低心脏事件发生,对血糖、血脂代谢没有明显影响。     

Ca~(2+)信号介导川芎嗪诱导小鼠骨髓间充质干细胞向神经细胞的定向分化

用含2.4 mg.mL-1川芎嗪提取液对小鼠骨髓间充质干细胞(BMSCs)进行诱导,探讨川芎嗪体外诱导BMSCs分化为神经元样细胞的作用.应用EGTA(细胞外Ca2+螯合剂)、Nifedipine(L-型Ca2+通道阻断剂)和LY294002(PI3K阻断剂)等Ca2+阻断剂分别作用细胞,RT-PCR和Western blot技术研究Ca2+信号在川芎嗪诱导BMSCs分化为神经细胞过程中的作用.结果表明:川芎嗪作用不同时间的BMSCs均可见Nestin、β-Tubulin Ⅲ、NSE和Nurrl的表达;川芎嗪诱导后的细胞浆内Nestin和NSE蛋白表达呈阳性.EGTA、Nifedipine及LY294002分别阻断细胞外Ca2+、L-型Ca2+通道及PI3K后,NSE和Nurr1基因及NSE蛋白表达较川芎嗪诱导组显著上调.以上结果说明川芎嗪能使BMSCs定向分化为神经元样细胞,细胞内、外Ca2+的减少可促进川芎嗪诱导BMSCs向神经细胞的分化,Ca2+信号在川芎嗪诱导BMSCs向神经细胞定向分化过程中起负调控作用.     

Inositol 1,3,4,5-tetrakisphosphate induces Ca2+ sequestration in rat liver cells

Inositol 1,4,5-trisphosphate [I(1,4,5)P3] is a second messenger generated along with diacylglycerol upon the binding of various physiological agents with their cell surface receptors. I(1,4,5)P3 mobilizes Ca2+ from intracellular storage sites through a receptor-coupled mechanism, and the subsequent increased intracellular free calcium ion concentration [( Ca2+]i) activates a multitude of cellular responses. Electropermeabilized neoplastic rat liver epithelial (261B) cells were used to study Ca2+ sequestration, a process that reverses the elevated [Ca2+]i to resting levels and replenishes intracellular Ca2+ pools. Although I (1,4,5)P3-mobilized Ca2+ is readily sequestered into storage pools by the action of Ca2+-adenosine triphosphatases, Ca2+ mobilized by addition of the nonmetabolized inositol trisphosphate isomer I(2,4,5)P3 is not sequestered, suggesting that metabolism is necessary to eliminate the stimulus for Ca2+ release. Several inositol phosphate compounds were examined for their ability to lower the buffer [Ca2+] to determine if a specific I(1,4,5)P3 metabolite might be involved in stimulating Ca2+ sequestration; of these, I(1,3,4,5)P4 alone was found to induce Ca2+ sequestration, demonstrating a physiological role for this inositol trisphosphate metabolite.     

Effect of Indole Butyric Acid on the Transportation of Stored Calcium in Malus hupehensis Rhed. Seedling

Calcium （Ca） plays an important role in the metabolism of higher plants. Recently, research on Ca^2＋ in plants has been focused especially at the cellular and molecular levels. Uptake, transport, and distribution are also very important for Ca to accomplish its function at the whole-plant level. In this experiment, one-year-old apple seedlings （M. hupehensis Rehd.） were investigated to determine the distribution of stored Ca, the different forms of Ca, and Ca^2＋-ATPase activity after treatment with indole butyric acid （IBA）. The results showed that the total Ca measured in mature leaves and Ca^2＋- ATPase activity in tender leaves were higher compared with those in the control （CK）. Calcium nitrate and calcium chloride （ALe-Ca） and calcium phosphate and calcium carbonate （HAC-Ca） decreased in both mature leaves and shoots, whereas water-soluble calcium （H2O-Ca）, calcium pectate （NaCl-Ca）, and calcium oxalate （HCl-Ca） increased. The percentage of active calcium, calcium pectate, and water-soluble calcium increased, whereas the percentage of calcium phosphate and calcium carbonate decreased. When treated with IBA, calcium fractions and percentage of the different forms of Ca was enhanced in 40 part per million （ppm） IBA compared with 20 ppm IBA and water. The results indicated that IBA increased the percentage of both active calcium （NaCl-Ca and H2O-Ca） in tender shoots and boosted the transportation of stored Ca in plants. IBA promoted Ca^2＋-ATPase activity and Ca^2＋ uptake in tender shoots of M. hupehensis. It can improve the total Ca contents and the relative percentage of Ca.     

Abnormal coronary function in mice deficient in alpha1H T-type Ca2+ channels

Calcium ion (Ca2+) influx through voltage-gated Ca2+ channels is important for the regulation of vascular tone. Activation of L-type Ca2+ channels initiates muscle contraction; however, the role of T-type Ca2+ channels (T-channels) is not clear. We show that mice deficient in the alpha1H T-type Ca2+ channel (alpha(1)3.2-null) have constitutively constricted coronary arterioles and focal myocardial fibrosis. Coronary arteries isolated from alpha(1)3.2-null arteries showed normal contractile responses, but reduced relaxation in response to acetylcholine and nitroprusside. Furthermore, acute blockade of T-channels with Ni2+ prevented relaxation of wild-type coronary arteries. Thus, Ca2+ influx through alpha1H T-type Ca2+ channels is essential for normal relaxation of coronary arteries.     

A magnesium current in Paramecium

Recent reappraisals of the role of ionized magnesium in cell function suggest that many cells maintain intracellular free Mg2+ at low concentrations (0.1 to 0.7 mM) and that external agents can influence cell function via changes in intracellular Mg2+ concentration. Depolarization and hyperpolarization of voltage-clamped Paramecium elicited a Mg2(+)-specific current, IMg. Both Co2+ and Mn2+ were able to substitute for Mg2+ as charge carriers, but the resultant currents were reduced compared with Mg2+ currents. Intracellular free Mg2+ concentrations were estimated from the reversal potential of IMg to be about 0.39 mM. The IMg was inhibited when external Ca2+ was removed or a Ca2+ chelator was injected, suggesting that its activation was Ca2(+)-dependent.