细胞钙转运系统研究进展*

钙离子是重要的细胞信号分子。胞内和胞外、胞浆和细胞器之间的Ca2+转运都依赖于钙转运系统的精确调控。钙转运系统包括钙泵、钙通道、Na^+/Ca^2+交换体及膜结构域,如质膜的PMCA、NCX、VGCC、LGCC和TRP通道;内质网膜的SERCA、IP3Rs和RyRs等;线粒体的MCU和NCLX;内溶酶体的TPCs;联结质膜和内质网膜的CRAC通路;联结内质网膜和线粒体膜的MAM结构域等。本文对定位于质膜、内质网和线粒体的钙转运系统的种类、功能、组织分布、相关疾病以及抑制剂作综述。     

钙库操纵性钙通道的激活信号分子在心血管疾病中的研究进展

近年来,心血管疾病的发生率逐年上升,细胞内Ca2＋失衡是其重要的发病机制.细胞膜表面受体活化后激活磷脂酶C,磷脂酶C作用于磷脂酰肌醇4,5-二磷酸使其分解为三磷酸肌醇和二酰甘油,三磷酸肌醇与内质网膜上受体结合,使Ca2＋从内质网释放进入胞质.随着胞内钙库的排空,位于质膜上的Ca2通道被激活,使Ca2＋由细胞外进入细胞质内,这个过程被称为钙库操纵的钙内流,其通道称为钙库操纵的钙通道（SOCC）[1].SOCC在维持细胞内Ca2稳态中扮演的角色越来越受到关注,细胞内这一稳态的打破将推动心血管疾病的发生与发展.现就SOCC的信号分子在心血管病研究中的进展作一综述.     

成骨细胞跨膜转运锌特性及其机制的初步研究

目的　研究锌在成骨细胞跨膜转运的动力学特点及影响因素 ,为阐明锌在骨发育中的作用提供科学依据。方法　采用65Zn同位素示踪法研究锌在成骨细胞跨膜转运的动力学特点 ;分别研究组氨酸、Na+、K+泵抑制剂、Ca2 +离子通道阻滞剂对成骨细胞锌转运的影响。结果　细胞外锌浓度增加可以促进锌转运入胞内 ,但锌缺乏使锌胞内转运减少 ;组氨酸、Na+、K+泵抑制剂对锌转运无影响 ;Ca2 +离子通道阻滞剂促进锌内流。结论　成骨细胞外环境锌水平可以影响成骨细胞锌转运及胞内锌水平 ,Ca2 +离子通道与Zn2 +通道可能相互影响     

灯盏花素对人脐静脉内皮细胞胞内Ca~(2+)水平的调控作用

目的探讨灯盏花素对培养的人脐静脉内皮细胞(HUVECs)胞内Ca2+水平([Ca2+]i)的调控作用。方法采用新一代Ca2+荧光探针Fluo-3/AM标记培养的HUVECs,激光共聚焦显微镜检测细胞胞内钙荧光信号,观察灯盏花素对培养的HUVECs胞内Ca2+水平的调控作用。结果在胞外有Ca2+或无Ca2+的情况下,灯盏花素均可引起[Ca2+]i的短暂性升高;灯盏花素的Ca2+释放作用与钙泵抑制剂CPA存在着交迭;灯盏花素能够抑制由KCl所引起的[Ca2+]i的升高;灯盏花素对胞内Ca2+池耗竭后胞外复Ca2+所引起的钙内流无明显阻断作用。结论灯盏花素可引起胞内Ca2+池的Ca2+释放,其释放的Ca2+来自CPA敏感的Ca2+池。灯盏花素也可抑制经电压依赖性Ca2+通道的Ca2+内流,对Ca2+池耗竭后引起的Ca2+内流通道无明显阻断作用。     

Ca^（2＋）和神经元死亡

神经元是一种可兴奋性细胞,能迅速以一种可控制方式传递电化学信号。神经元内对化学和电信号刺激做出反应的主要信使是Ca2 。Ca2 通过质膜上的电压依赖性和配体型钙通道进入胞质内,是突触前膜释放神经递质的关键信号。胞内Ca2 调节系统的失调将造成突触功能失调、     

Ca~(2+)信号通道与胰腺炎

胰腺炎至今尚缺乏有效的治疗药物。近年来发现胞内Ca2+超负荷能导致胰腺炎的发生。该文综述了胰腺炎早期胰腺腺泡细胞内Ca2+转运的变化和胆盐、乙醇、高脂对其影响,以及咖啡因抑制异常Ca2+信号的作用,并据此提出研究防治药物的新靶点。     

大蒜新素对脑缺血再灌注大鼠海马的保护作用

目的探讨大蒜新素对脑缺血再灌注海马组织的保护作用与钙转运的关系。方法采用4血管闭塞法制备大鼠全脑缺血再灌注模型,大蒜新素10,20和30mg.kg-1分2次于缺血前30min和再灌注后10min经尾静脉注入,每次注射总量的1/2。再灌注后24h取大鼠海马,甲苯胺蓝染色显微镜下观察海马组织学改变及存活神经元密度;定磷比色法测定Ca2+-转运ATP酶活性;原子吸收法测定钙含量。结果全脑缺血10min再灌注24h时,海马CA1区形态学改变明显,神经元密度明显降低;海马组织Ca2+-转运ATP酶活性降低;组织钙含量显著增加。静脉给予大蒜新素可使缺血再灌注海马组织形态学改变程度明显减轻,存活神经元密度增加,Ca2+-转运ATP酶活性增加,组织钙含量降低。结论大蒜新素对全脑缺血再灌注后海马组织具有明显的保护作用;增加Ca2+-转运ATP酶活性、减少组织钙含量可能是其保护作用的机制之一。     

钙调蛋白抑制剂三氟拉嗪对癫痫大鼠学习和记忆的影响

<正>目前Ca2+与癫痫的关系已经肯定,钙稳态是维持神经元正常功能活动的基础,被破坏后可以触发一系列病理改变,胞内钙浓度和胞膜钙流的增加在癫痫发生上起重要作用。钙     

川芎嗪衍生物对人阴茎海绵体平滑肌细胞游离钙浓度的影响

目的研究川芎嗪（TMP）衍生物（A3 A6）对人阴茎海绵体平滑肌细胞（PCSMC）胞质内游离钙离子（Ca2+）浓度的影响。方法采用新型Ca2＋荧光染色剂Fluo 3/AM负载人PCSMC,应用激光扫描共聚焦显微镜（LSCM）实时测定胞质内［Ca2＋］i变化。以母体川芎嗪和经典钙拮抗药维拉帕米 （Ver）为阳性对照,分别观察A3 A6对去甲肾上腺素（NE）诱导胞质内钙浓度升高的影响。结果在浓度0.2 mmol&#8226;L 1时,A3 A6对NE诱发的人PCSMC内［Ca2＋］i升高有明显抑制作用,抑制率分别为49.03%,54.83%,51.48%和50.31%,优于TMP（18.96%）,远大于Ver（16.51%）（P＜0.05）。结论A3 A6对人PCSMC电压依赖性钙通道均有抑制作用,能降低PCSMC胞质内Ca2+水平,其作用效果均比TMP强。     

乌贼墨对H22癌细胞TPK、PKC及PKA活性的影响

利用γ-^23P－ATP作为反应启动剂掺入外源性底物的方法测定TPK、PKC及PKA活性,研究了乌贼墨对H22癌细胞TPK、PKC及PKA活性的影响。结果表现：癌细胞质膜、胞浆及线粒体TPK活性均显著升高而以质膜TPK活性升高最为显著;胞浆、线粒体及胞核PKC活性均显著升高而以胞核PKC升高最为明显;胞浆内PKA活性升高。给予乌贼墨作用后,癌细胞质膜、胞冻及线粒体TPK活性均显著下降;线粒体及胞核PKC活性均显著下降,胞浆PKA活性继续明显升高。结果提示：乌贼墨能明显的逆转癌细胞异常改变的TPK、PKC和PKA活性,引起Ras－MAPK信号传导系统的正调节作用减弱和负调节作用增强,结果抑制或阻断了Ras－MAPK信号传导系统的信号及联传导,使癌细胞由去分化性增殖向分化增殖转变,产生抗癌促分化作用。     

Inhibition of Ca2+ influx is required for mitochondrial reactive oxygen species-induced endoplasmic reticulum Ca2+ depletion and cell death in leukemia cells

Disturbances of endoplasmic reticulum (ER) Ca2+ homeostasis or protein processing can lead to ER stress-induced cell death. Increasing evidence suggests that oxidative stress (OS) plays an important role in a variety of cell death mechanisms. To investigate the role of OS in ER stress, we measured OS in response to three ER stress agents: econazole (Ec), which stimulates ER Ca2+ release and blocks Ca2+ influx; thapsigargin (Tg), a sarco(endo)plasmic reticulum Ca2+ ATPase inhibitor that releases ER Ca2+ and stimulates Ca2+ influx; and tunicamycin (Tu), a glycosylation inhibitor that causes protein accumulation in the ER. Ec, but not Tg or Tu, caused a rapid increase in OS. Reactive oxygen species (ROS) generation was observed within mitochondria immediately after exposure to Ec. Furthermore, Ec hyperpolarized the mitochondrial membrane and inhibited adenine nucleotide transport in cell-free mitochondria, suggesting a mitochondrial target. Antimycin A, an inhibitor of complex III in electron transport, reversed mitochondrial hyperpolarization, OS generation, ER Ca2+ depletion, and cell death by Ec, suggesting complex III dependence for these effects. Antioxidants butylated hydroxytoluene and N-Acetyl-L-cysteine prevented ER Ca2+ depletion and cell death by Ec. However, inhibition of Ca2+ influx by Ec was unaffected by either antimycin A or the antioxidants, suggesting that this target is distinct from the mitochondrial target of Ec. Atractyloside, an adenine nucleotide transport inhibitor, generated ROS and stimulated ER Ca2+ release, but it did not block Ca2+ influx, deplete the ER or induce cell death. Taken together, these results demonstrate that combined mitochondrial ROS generation and Ca2+ influx blockade by Ec is required for cell death.     

Endoplasmic reticulum Ca(2+) handling in excitable cells in health and disease

The endoplasmic reticulum (ER) is a morphologically and functionally diverse organelle capable of integrating multiple extracellular and internal signals and generating adaptive cellular responses. It plays fundamental roles in protein synthesis and folding and in cellular responses to metabolic and proteotoxic stress. In addition, the ER stores and releases Ca(2+) in sophisticated scenarios that regulate a range of processes in excitable cells throughout the body, including muscle contraction and relaxation, endocrine regulation of metabolism, learning and memory, and cell death. One or more Ca(2+) ATPases and two types of ER membrane Ca(2+) channels (inositol trisphosphate and ryanodine receptors) are the major proteins involved in ER Ca(2+) uptake and release, respectively. There are also direct and indirect interactions of ER Ca(2+) stores with plasma membrane and mitochondrial Ca(2+)-regulating systems. Pharmacological agents that selectively modify ER Ca(2+) release or uptake have enabled studies that revealed many different physiological roles for ER Ca(2+) signaling. Several inherited diseases are caused by mutations in ER Ca(2+)-regulating proteins, and perturbed ER Ca(2+) homeostasis is implicated in a range of acquired disorders. Preclinical investigations suggest a therapeutic potential for use of agents that target ER Ca(2+) handling systems of excitable cells in disorders ranging from cardiac arrhythmias and skeletal muscle myopathies to Alzheimer disease.     

SERCA stimulation: A potential approach in therapeutics

sarco–endoplasmic reticulum Ca‐ATPase (SERCA) is the major transporter present in sarco–endoplasmic reticulum (SR/ER), transporting calcium back into SR/ER from cytosol. The calcium‐sequestering activity of SERCA facilitates relaxation in both cardiac and skeletal tissue. ER stress is one of the etiological factors in various diseases such as neurodegenerative diseases and diabetes. Disrupted calcium handling can cause ER stress. In the cardiac tissue, impairment of systolic and diastolic function can cause various cardiovascular diseases. SERCA ensures the proper calcium handling in cells and may act as a therapeutic target for the disease associated with dysregulation of calcium ions. This review examines the principle of calcium ion handling through SERCA and its role in various diseases.     

Calcium alterations in Alzheimer's disease: pathophysiology, models and therapeutic opportunities.

Calcium plays a pivotal role in mediating many important biological functions. The intracellular calcium concentration is tightly regulated by a variety of systems and mechanisms. Calcium is sequestered by various organelles such as mitochondria and/or endoplasmic reticulum and extruded across the plasma membrane by energy-dependent transport systems. Different Ca2+-binding proteins are also involved in these processes. Alterations in calcium homeostasis might be critically implicated in brain aging and in the neuropathology of Alzheimer's disease (AD). In fact, one of the postulated mechanisms of beta-amyloid toxicity seems to involve a Ca2+ dysregulation accompanied with enhanced vulnerability to excitotoxic stimuli. Although brain characteristic lesions-plaques and tangles-constitute the hallmarks of AD, accumulated evidence suggests the systemic feature of this disease. Therefore peripheral cell lines may represent a useful approach to explore the cellular pathophysiology of AD, including calcium alterations and associated phenomena.     

Glial calcium signaling in physiology and pathophysiology

Neuronal-glial circuits underlie integrative processes in the nervous system. Function of glial syncytium is, to a very large extent, regulated by the intracellular calcium signaling system. Glial calcium signals are triggered by activation of multiple receptors, expressed in glial membrane, which regulate both Ca2+ entry and Ca2+ release from the endoplasmic reticulum. The endoplasmic reticulum also endows glial cells with intracellular excitable media, which is able to produce and maintain long-ranging signaling in a form of propagating Ca2+ waves. In pathological conditions, calcium signals regulate glial response to injury, which might have both protective and detrimental effects on the nervous tissue.     

Sodium fluoride increases intracellular calcium in rat renal epithelial cell line NRK-52E

In our previous experiment using rats, fluoride was reported to cause renal calcification, whose mechanism was deduced to be due to an increase in parathyroid hormone (PTH) secretion. However fluoride-induced renal calcification that was independent of PTH has not been understood well in the nephron of fluoride-treated animals. Thus, we examined the effect of sodium fluoride on intracellular calcium mobilization in a normal rat kidney epithelial cell line (NRK-52E cells). The calcium accumulation was found to be remarkably increased by the addition of sodium fluoride (NaF). The elevation of [Ca2+]i was demonstrated to be due to calcium entry through nifedipine-sensitive calcium channels. In addition, fluoride activates phospholipase C, but inositol 1,4,5-triphosphate (IP3) didn't induce Ca2+ release from the endoplasmic reticulum (ER). Moreover, fluoride alone was deduced to enhance the activity of ER-type Ca2+-ATPase. Finally, on the mechanism of fluoride-induced calcium accumulation in NRK-52E cells, fluoride may activate phospholipase C to generate IP3 and diacylglycerol, and these increases can be elucidated to induce calcium entry through dihydropiridine-sensitive calcium channels. Moreover, fluoride was found to stimulate calcium accumulation through ER-type Ca2+-ATPase into the endoplasmic reticulum. The elevation of ER-type Ca2+-ATPase activity by fluoride was elucidated to operate as a regulatory system to protect against abnormally higher increases in cytosolic calcium concentration via an increase of calcium influx into the endoplasmic reticulum.     

Main systems involved in calcium regulation in cardiac muscle cells and their functional relationship.

This article discusses interrelationship between various transport proteins in the regulation of intracellular calcium ion concentration in heart muscle cells. The depolarization of the plasma membrane of the cardiac muscle cell causes opening of the L-type calcium channels which triggers the opening of ryanodine receptor (RyR) and releases calcium from intracellular store in sarcoplasmic reticulum (SR) by the process of calcium-induced calcium release (CICR). A major factor responsible for the amount of calcium available during systole is loading of SR by SERCA. The amount of calcium released during systolic calcium transient affects the sarcolemmal Ca2+ and Na(+)-Ca2+ exchange currents. These processes control cell Ca2+ loading and amount of Ca2+ available for uptake by SR and for the next contraction. Each system involved in Ca2+ intracellular concentration is also regulated by physiological mediators and pharmacological compounds that can influence the heart muscle performance. A spatial organization of enzymatic and transport proteins that are responsible for a specific rise in local calcium concentration is also discussed.     

左旋氨氯地平对缺氧心肌细胞钙信号系统的影响

目的:观察缺氧对心肌细胞内游离钙离子浓度和细胞膜及肌浆网上钙离子泵,即Ca2+ AT Pase表达的影响及左旋氨氯地平的干预作用。方法:制备大鼠心肌细胞缺氧模型,随机分为正常对照组、缺氧损伤组和左旋氨氯地平组。测定心肌细胞内游离钙离子的浓度(FURA2 /AM荧光探针法)、细胞膜上Ca2+ ATPase表达水平(RT PCR法)以及肌浆网上钙泵(SERCA2 )含量(WesternBlot法)。结果:缺氧损伤组心肌细胞内游离钙离子浓度[ (716±s164)nmol·L-1 ]较正常对照组[ (208±32)nmol·L-1 ]显著上升(P<0. 01 ),细胞膜及肌浆网上钙泵的表达(0. 54±0. 12和158±15)较正常对照组( 0. 86±0. 07和210±12 )均明显降低(均P<0. 01),经左旋氨氯地平干预后细胞内游离钙浓度降低至(359±75 )nmol·L-1,P<0. 01,细胞膜上及肌浆网上钙泵的表达(0. 81±0. 11和184±11)均明显增强(均P<0. 01)。结论:左旋氨氯地平可能通过增加细胞膜及肌浆网上钙泵的表达有效减轻心肌细胞内的钙超载,对缺氧心肌具有保护作用。     

Priming of long-term potentiation mediated by ryanodine receptor activation in rat hippocampal slices

Administration of the Group 1 metabotropic glutamate receptor (mGluR) agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) facilitates ("primes") subsequent long-term potentiation (LTP) through a phospholipase C signaling cascade that may involve release of Ca2+ from the endoplasmic reticulum (ER). We investigated the intracellular calcium pathways involved in this priming effect, recording field potentials from area CA1 of rat hippocampal slices before and after high-frequency stimulation. The priming of LTP by DHPG was prevented by co-administration of cyclopiazonic acid, which depletes ER Ca2+ stores. The priming effect was also blocked by the ryanodine receptor (RYR) antagonist ryanodine (RYA, 100 microM). In contrast, a low dose of RYA (10 microM) which opens the RYR channel, by itself primed LTP. In addition to RYR activation, entry of extracellular calcium through store-operated channels appears necessary for priming, since diverse treatments known to impede store-operated channel activity completely blocked both RYA and DHPG priming effects. Thus, RYR activation plays a critical role in the priming of LTP by Group 1 mGluRs, and this effect is coupled to the entry of extracellular calcium, probably through store-operated calcium channels.