Ischemic postconditioning protects against ischemic brain injury by up-regulation of acid-sensing ion channel 2a

Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.

Identification and Function of Acid-sensing Ion Channels in RAW 264.7 Macrophage Cells

Activation of acid-sensing ion channels （ASICs） plays an important role in neuroinflammation. Macrophage recruitment to the sites of inflammation is an essential step in host defense. ASIC1 and ASIC3 have been reported to mediate the endocytosis and maturation of bone marrow derived macrophages. However, the expression and inflammation-related functions of ASICs in RAW 264.7 cells, another common macrophage, are still elusive. In the present study, we first demonstrated the presence of ASIC 1, ASIC2a and ASIC3 in RAW 264.7 macrophage cell line by using reverse transcriptase polymerase chain reaction （RT-PCR）, Western blotting and immunofluorescence experiments. The non-specific ASICs inhibitor amiloride and specific homomeric ASICla blocker PcTxl reduced the production of iNOS and COX-2 by LPS-induced activating RAW 264.7 cells. Furthermore, not only amiloride but also PcTxl inhibited the migration and LPS-induced apoptosis of RAW 264.7 cells. Taken together, our findings suggest that ASICs promote the inflammatory response and apoptosis of RAW 264.7 cells, and ASICs may serve as a potential novel target for immunological disease therapy.

Effect of Activation of the Ca2+-Permeable Acid-Sensing Ion Channel 1a on Acid-Induced Vascular Endothelial Cell Injury of Henoch-Schönlein Purpura Children

Acidosis in local environment plays a critical role in cell injury. One key mediator of acidosis-induced cell injury is the acid-sensing ion channels (ASICs), particularly ASIC1a. Herein, we investigated the role of ASIC1a in acid-induced vascular endothelial cell injury of Henoch-Schonlein purpura (HSP) children. Acid-induced ASIC1a, Calpain and Calcineurin expression in vascular endothelial cells pretreated with IgA1 isolated from HSP were detected by real time quantitative polymerase chain reaction and western blot methods, respectively. Cell cytotoxicity was measured by interleukin-8 and nitric oxide production with ELISA. The results showed acid-induced ASIC1a, Calpain and Calcineurin expression in cells increased, especially at PH6.5. The cytotoxicity of vascular endothelial cells was increased by extracellular acidosis. Moreover non-specific or specific blockers of ASIC1a, Amiloride and PcTX-1 could remarkably decrease these parameters. These findings show that increased [Ca2+]i, mediated via ASIC1a, might contribute to acid-induced vascular endothelial cell injury of HSP.

An optimized recording method to characterize biophysical and pharmacological properties of acid-sensing ion channel

Objective To re-confirm and characterize the biophysical and pharmacological properties of endogenously expressed human acid-sensing ion channel 1a （hASIC1a） current in HEK293 cells with a modified perfusion methods. Methods With cell floating method, which is separating the cultured cell from coverslip and putting the cell in front of perfusion tubing, whole cell patch clamp technique was used to record hASICla currents evoked by low pH external solution. Results Using cell floating method, the amplitude of hASICla currents activated by pH 5.0 in HEK293 cells is twice as large as that by the conventional method where the cells remain attached to coverslip. The time to reach peak at two different recording conditions is （21±5） ms and （270±25） ms, respectively. Inactivation time constants are （496±23） ms and （2284±120） ms, respectively. The cell floating method significantly increases the amiloride potency of block on hASIC 1 a [IC50 is （3.4± 1.1 ） μmol/L and （2.4± 0.9） μmol/L, respectively]. Both recording methods have similar pH activation ECs0 （6.6±0.6, 6.6±0.7, respectively）. Conclusion ASICs channel activation requires fast exchange of extracellular solution with the different pH values. With cell floating method, the presence of hASIC la current was re-confirmed and the biophysical and pharmacological properties of hASIC la channel in HEK293 cells was precisely characterized. This method could be used to study all ASICs and other ligand-gated channels that require fast extracellular solution exchange.

Involvement of Acid-sensing Ion Channel 1a in Functions of Cultured Human Retinal Pigment Epithelial Cells

In the retina, pH fluctuations may play an important role in adapting retinal responses to different light intensities and are involved in the fine tuning of visual perception. Acidosis occurs in the subretinal space （SRS） under pathological conditions such as age-related macular degeneration （AMD）. Although it is well known that many transporters in the retinal pigment epithelium （RPE） cells can maintain pH homeostasis efficiently, other receptors in RPE may also be involved in sensing acidosis, such as acid-sensing ion channels （ASICs）. In this study, we investigated whether ASICla was ex- pressed in the RPE cells and whether it was involved in the function of these cells. Real-time RT-PCR and Western blotting were used to analyze the ASICla expression in ARPE-19 cells during oxidative stress induced by hydrogen peroxide （H202）. Furthermore, inhibition or over-expression of ASICla in RPE cells was obtained using inhibitors （amiloride and PCTxl） or by the transfection of cDNA encod- ing hASICla. Cell viability was determined by using the MTT assay. The real-time RT-PCR and West- ern blotting results showed that both the mRNA and protein of ASICla were expressed in RPE cells. In- hibition of ASICs by amiloride in normal RPE cells resulted in cell death, indicating that ASICs play an important physiological role in RPE cells. Furthermore, over-expression of ASICla in RPE cells pro- longed cell survival under oxidative stress induced by H2O2. In conclusion, ASICla is functionally expressed in RPE cells and may play an important role in the physiological function of RPE cells by pro-tecting them from oxidative stress.

Does closure of acid-sensing ion channels reduce ischemia/reperfusion injury in the rat brain?

Acidosis is a common characteristic of brain damage. Because studies have shown that permeable Ca2＋-acid-sensing ion channels can mediate the toxic effects of calcium ions, they have become new targets against pain and various intracranial diseases. However, the mechanism associated with expression of these channels remains unclear. This study sought to observe the expression characteristics of permeable Ca2＋-acid-sensing ion channels during different reperfusion inflows in rats after cerebral ischemia. The rat models were randomly divided into three groups： adaptive ischemia/reperfusion group, one-time ischemia/reperfusion group, and severe cerebral ischemic injury group. Western blot assays and immunofluorescence staining results exhibited that when compared with the one-time ischemia/reperfusion group, acid-sensing ion channel 3 and Bcl-x/I expression decreased in the adaptive ischemia/reperfusion group. Calmodulin expression was lowest in the adaptive ischemia/reperfusion group. Following adaptive reperfusion, common carotid artery flow was close to normal, and the pH value improved. Results verified that adaptive reperfusion following cerebral ischemia can suppress acid-sensing ion channel 3 expression, significantly reduce Ca2＋ influx, inhibit calcium overload, and diminish Ca2＋ toxicity. The effects of adaptive ischemia/reperfusion on suppressing cell apoptosis and relieving brain damage were better than that of one-time ischemia/reperfusion.

Advances and challenges of electrolyzers for large-scale CO_(2) electroreduction

CO_(2) electroreduction(CO_(2) ER)to high value-added chemicals is considered as a promising technology to achieve sustainable carbon neutralization.By virtue of the progressive research in recent years aiming at design and understanding of catalytic materials and electrolyte systems,the CO_(2) ER performance(such as current density,selectivity,stability,CO_(2) conversion,etc.)has been continually increased.Unfortunately,there has been relatively little attention paid to the large-scale CO 2 electrolyzers,which stand just as one obstacle,alongside series-parallel integration,challenging the practical application of this infant technology.In this review,the latest progress on the structures of low-temperature CO_(2) electrolyzers and scale-up studies was systematically overviewed.The influence of the CO_(2) electrolyzer configurations,such as the flow channel design,gas diffusion electrode(GDE)and ion exchange membrane(IEM),on the CO_(2) ER performance was further discussed.The review could provide inspiration for the design of large-scale CO_(2) electrolyzers so as to accelerate the industrial application of CO_(2) ER technology.

多囊蛋白2离子通道功能及在常染色体显性多囊肾发病中的作用机制

多囊蛋白2 (polycystin-2,PC2,或称TRPP2,PKD2)是一种瞬时受体电位通道(transient receptor potential channel,TRP),在维持细胞正常的Ca~(2+)信号传导中起着关键作用,也是最常见的单基因常染色体显性遗传多囊肾病(transient receptor potential channel,ADPKD)的潜在病因之一。PC2可自身组装为同源四聚体离子通道或与其他蛋白质形成异源受体-离子通道复合物,参与调节机械感觉、细胞极性、细胞增殖和凋亡等多种生理功能,导致囊性细胞从正常的吸收、静止状态转变为病理性分泌、增殖状态。本文阐述了PC2蛋白相关结构域以及通道特性在维持细胞内Ca~(2+)信号传导中的关键作用,并总结了PC2在细胞膜、纤毛、内质网以及线粒体等特定亚细胞定位形成多囊蛋白复合物,参与多种细胞分化、增殖、存活和凋亡相关信号通路,为确定特异性的有效的ADPKD干预治疗途径和靶点药物提供新的思考方向。

Effects of interlayer spacing and applied pressure on the lanthanide transport in MoS2-based two-dimensional channels

Rare-earth elements(REEs)are critical to modern industry but difficult to separate due to their subtle and monotonic changes in physico-chemical properties.MoS2-based two-dimensional(2D)materials offer novel opportunities for enhancing REE separation,exhibiting a distinct volcano-shaped transport performance distribution that peaks at Sm3+.However,the specific contributions of thermodynamic and kinetic factors to ion transport within 2D confinement remain unclear.In this study,we conducted a series of non-equilibrium all-atom molecular dynamics(MD)simulations to explore the effects of interlayer spacing and external pressure on the transport of lanthanide ions inÅ-scale acetate functionalized 2D MoS2(MoS2-COOH)channels.We examined ion entry and permeation rates,water flux,dehydration,and binding modes.The simulation results reveal that the transport trends of lanthanide ions are jointly driven by the dehydration degree and the relative-binding strengths of ions to water and to the acetate within the 2D channels.Notably,the dehydration pattern of lanthanide ions during permeation is closely linked to kinetic factors.Overall,this study provides a detailed atomistic understanding of the mechanisms under-lying lanthanide ion transport under confinement.These findings point to the significant potential for tuning confinement and chemical functionalization withinÅ-scale channels for more efficient REE separation.

基于嘌呤配体P2X门控离子通道型受体7的资生肾气丸镇痛机制研究

目的:探索资生肾气丸对醋酸致小鼠扭体模型的镇痛作用。方法:将42只小鼠随机分为7组,分别给予相应药液灌胃,末次灌胃1 h后造模,建立醋酸致小鼠扭体模型。观察小鼠扭体次数,计算其扭体抑制率,应用酶联免疫吸附试验(ELISA)检测各组小鼠血清白细胞介素-1β(IL-1β)、前列腺素E 2(PGE 2)、神经生长因子(NGF)含量,采用实时PCR(RT-PCR)检测嘌呤配体P2X门控离子通道型受体7(P2X7R)mRNA、Nod样受体蛋白3(NLRP3)mRNA、NIMA相关激酶7(NEK7)mRNA的表达情况。结果:与模型组比较,随着时间的增加,资生肾气丸低剂量、中剂量、高剂量均可抑制小鼠扭体反应,降低扭体次数,增加小鼠扭体抑制率,降低小鼠血清中IL-1β、PGE_(2)、NGF的含量,降低P2X7RmRNA、NLRP3mRNA、NEK7mRNA的表达以抑制疼痛反应,以高剂量效果最优(P<0.05),与吲哚美辛、痛风舒片疗效相近。结论:资生肾气丸高剂量对小鼠血清疼痛因子的降低效果显著,其机制可能与嘌呤配体P2X门控离子通道型受体7信号通路有关。

Diabetes-induced changes in cardiac voltage-gated ion channels

Diabetes mellitus affects the heart through various mechanisms such as microvascular defects,metabolic abnormalities,autonomic dysfunction and incompatible immune response.Furthermore,it can also cause functional and structural changes in the myocardium by a disease known as diabetic cardiomyopathy(DCM)in the absence of coronary artery disease.As DCM progresses it causes electrical remodeling of the heart,left ventricular dysfunction and heart failure.Electrophysiological changes in the diabetic heart contribute significantly to the incidence of arrhythmias and sudden cardiac death in diabetes mellitus patients.In recent studies,significant changes in repolarizing K+currents,Na+currents and L-type Ca^(2+)currents along with impaired Ca^(2+ )homeostasis and defective contractile function have been identified in the diabetic heart.In addition,insulin levels and other trophic factors change significantly to maintain the ionic channel expression in diabetic patients.There are many diagnostic tools and management options for DCM,but it is difficult to detect its development and to effectively prevent its progress.In this review,diabetes-associated alterations in voltage-sensitive cardiac ion channels are comprehensively assessed to understand their potential role in the pathophysiology and pathogenesis of DCM.

Electrophysiological Study of V535M hERG Mutation of LQT2

This study examined the current changes of human ether-a-go-go-related gene （hERG） mutation derived from a LQT2 Chinese family with a highly penetrating phenotype. Mutation was identi-fied and site-directed mutagenesis was performed to induce the mutation in wild-type （WT） hERG. WT hERG and mutated V535M were cloned and transiently expressed in HEK293 cells. At the 48th and 72nd h after transfection, membrane currents were recorded using whole cell patch-clamp procedures. An A〉G transition at 1605 resulting in replacement of V535M was identified. Compared to WT, V535M mutation significantly decreased tail currents of hERG. At test potential of-40 mV after depolarizing at ＋50 mV, tail current densities were 83.354-7.06 pA/pF in WT and 50.38-4-7.74 pA/pF in V535M respectively （n=20, P〈0.01）. Gating kinetics of bERG revealed that Vl/2 of steady-state inactivation shifted to negative potential in the mutant （V1/2,v535M： -61.814-1.7 mV vs. V1/2, wx： -43.1q-0.71 mV）. The time constant of recovery from inactivation was markedly prolonged in the mutant compared to WT among test potentials. V535M hERG mutation demonstrated markedly decreased tail current densities, which suggests that V535M is a new loss-of-function mutation of hERG channel responsible for LQT2.

Ablation of TRPV4 in HepG2 with Its CRISPR/Cas9 Enhances Its Wound Healing

TRPV4 activity modulates cell activities including receptor trafficking and transcriptional or translational regulations. We tested its CRISPR/Cas9 scissor efficacy in HepG2 (HEK293) cell noticed that it worked well in both cell lines to eliminate TRPV4 genome sequences. To confirm TRPV4 functions in the cell morphology maintenance and cell growth (beyond Ca2+ channel), we compared its wound healing, cell surface area, survival property and soft agar growth ability after deletion of TRPV4 gene in the cells with its CRISPR/Cas9 system. With these experiments, we confirmed that TRPV4 is required not only to function as Ca2+ channel but also to maintain its proper cell morphology as a corner stone protein on the cell adhesion junction.

Engineering two-dimensional pores in freestanding TiO_2/graphene gel film for high performance lithium ion battery

As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.

Mechanisms of Cyclovirobuxine D on APD Prolongation in Rat Ventricular Myocytes

Aim To study the effects of cyclovirobuxine D on inward rectifier K^- current(I_(k1) ) > transient outward K^+ current (I_(to)), L-type Ca^(2+) current (I_(Ca-L)), and actionpotential duration (APD) in isolated rat ventricular myocytes. Methods The whole cell patch-clamptechniques were used to study the changes of I_(k1), I_(to), I_(Ca-L) and APD in rat ventricularmyocytes. Results Cyclovirobuxine D (1-10 μmol·L^(-1)) significantly prolonged APD_(50) andAPD_(90) in isolated rat ventricular myocytes. Resting potential (RP) was decreased by 10μmol·L^(-1) of cyclovirobuxine D. Cyclovirobuxine D significantly decreased both inward andoutward components of I_(k1) . At - 100 mV, 1 and 10 μmol·L^(-1) of cyclovirobuxine D decreasedI_(k1), density from (-8.0+- 1.1) pA/pF to ( - 4.1 +- 0.7) pA/pF and ( - 3.4 +- 0.8) pA/pF,respectively, whereas at - 30 mV, I-(k1) density was decreased from (1.10 +-0.24) pA/pF to (0.61+-0.18) pA/pF and (0.36+- 0.11) pA/pF, respectively. 1_(to) was markedly inhibited bycyclovirobuxine D from the test potential of 0 mV to + 60 mV. At + 40 mV, 1 and 10μmol·L^(-1) ofcyclovirobuxine D decreased I_(to) density from (8.9+- 2.0) pA/pF to (5.5 +- 1.2) pA/pF and (4.9+-0.9) pA/pF, respectively. Cyclovirobuxine D inhibited I_(Ca-L) in a concentration-dependentmanner. At 10 mV, 1 and 10μmol·L^(-1) of cyclovirobuxine D decreased I_(Ca-L) density from ( - 9.9+- 1.8) pA/pF to ( - 6.4 +- 1.4) pA/pF and (-4.2+-0.6) pA/pF, respectively. ConclusionCyclovirobuxine D significantly prolonged APD and inhibited I_(k1), I_(to), and I_(Ca-L) in ratventricular myocytes. The inhibitory effects of cyclovirobuxine D on _(k1) and I_(to) are majormolecular mechanisms of APD prolongation in rat.

ERK1/2对低氧大鼠肺动脉平滑肌细胞Kv1.5通道表达的影响

目的：探讨ERK1/2对低氧大鼠肺动脉平滑肌细胞（PASMCs）电压门控性钾离子通道（Kv1.5）表达的影响及其机制。方法：原代培养SD大鼠PASMCs,选3-6代PASMCs随机分组：1正常组（N）;2低氧组（H）;3DMSO组（HD）;4U0126组（HU）：10μmol/L U0126;5茴香霉素组（HA）：10μmol/L茴香霉素。每组3皿细胞,正常组于常氧培养箱（5%CO2,37℃）,其余各组均加入0.05%二甲基亚砜（DMSO）于低氧培养箱（5%CO2,2%O2,37℃）,均培养60 h。采用RT-PCR和Western blot法测定PASMCs Kv1.5 mRNA和蛋白表达。结果：与N组相比,H、HD、HA组Kv1.5 mRNA和蛋白表达均明显降低（P〈0.05）;较之H和HD组,HU组Kv1.5 mRNA和蛋白表达明显上升（（P〈0.05）,与HU组比较,HA组Kv1.5 mRNA和蛋白表达均明显降低（P〈0.05）。结论：低氧降低Kv1.5 mRNA和蛋白表达,U0126能够对抗低氧引起的Kv1.5通道的低表达,茴香霉素对低氧条件下Kv1.5通道表达无明显影响,但其表达仍显著低于常氧组,提示低氧可能通过干预ERK1/2信号通路抑制Kv1.5通道表达引起低氧性肺动脉高压。

阻断氯离子通道对荷Hep-2细胞瘤裸鼠移植瘤生长、细胞凋亡及Oct4和CD133蛋白表达的影响

目的:研究阻断氯离子通道对荷Hep-2细胞瘤裸鼠移植瘤的抑制作用及可能机制。方法:以Hep-2细胞建立裸鼠皮下移植瘤模型,应用不同浓度(0、10、50、100和150μmol/L)的氯离子通道阻断剂(NPPB)处理4周,每组6只。观察移植瘤体积的变化,采用TUNEL染色检测移植瘤组织细胞凋亡情况,免疫组化法检测移植瘤组织Oct4和CD133蛋白的表达。结果:不同浓度的NPPB组间移植瘤体积、细胞凋亡指数及Oct4和CD133蛋白的阳性表达率差异均有统计学意义(F=7.361、126.385,P均<0.05);与对照组(0μmol/L NPPB组)相比,50、100和150μmol/L NPPB组移植瘤体积减小,细胞凋亡指数升高,Oct4和CD133蛋白的阳性表达率降低(P<0.05或0.005)。结论:体内阻断氯离子通道可抑制荷Hep-2细胞瘤裸鼠移植瘤的生长,诱导肿瘤细胞凋亡,其机制可能与降低Oct4和CD133蛋白的表达有关。

hHCN2基因转染的脂肪组织来源的成体干细胞可分化为起搏样细胞

目的大鼠脂肪来源的成体干细胞(ADSC)转染人超极化激活环核苷酸门控离子通道-2(hHCN2)基因,观察其作为起搏细胞的可行性。方法取生长良好的ADSC转染hHCN2基因,通过RT-PCR、Western blot分析、免疫荧光技术检测hHCN2基因及蛋白的表达,用膜片钳技术检测细胞的电生理特征并记录其内向电流。将转染hHCN2基因的ADSC与心室肌细胞共培养,观察其对心室肌细胞自发性搏动的影响。结果 hHCN2基因修饰的大鼠ADSC能表达较强的hHCN2基因及蛋白,还能够产生超级化激活内向离子流。将其与心室肌细胞共培养,能使心室肌细胞的自发性搏动明显增快增强。结论将hHCN2基因转染ADSC能够使其分化为具有起搏功能的起搏样细胞,为进一步优化生物起搏器的研究提供了材料。

Verapamil和Mn^（2＋）对缺氧和复氧心肌细胞内Na~＋浓度的影响

采用荧光探针ＳＢＦＩ／ＡＭ结合计算机图像处理技术测定缺氧和复氧时单心肌细胞内Ｎａ＋的变化及钙通道阻滞剂Ｖｅｒａｐａｍｉｌ和Ｎａ＋－Ｃａ２＋交换抑制剂Ｍｎ２＋对其的影响。结果表明随缺氧和复氧时间的延长细胞内Ｎａ＋均增加。Ｖｅｒａｐａｍｉｌ对缺氧或复氧细胞内Ｎａ＋无影响（Ｐ＞０．０５），Ｍｎ２＋能使复氧细胞内Ｎａ＋含量增加（Ｐ＜０．０１）。本文推断Ｖｅｒａｐａｍｉｌ不是通过降低细胞内Ｎａ＋浓度而发挥保护心肌作用，特异性强的Ｎａ＋－Ｃａ２＋交换抑制剂会使复氧心肌细胞内Ｎａ＋含量增加而削弱其保护作用。

大鼠酸感受离子通道亚基2a表达质粒的构建及生物学特性考察

目的构建大鼠酸感受离子通道亚基2a(acid-sensingion channel subunit 2a,ASIC2a)的表达质粒并研究其组成的同聚体离子通道的生物学特性。方法使用分子生物学技术构建大鼠ASIC2a亚基表达质粒;通过体外转录技术,使编码ASIC2a亚基的cRNA在爪蟾卵母细胞内表达并在膜表面形成同聚体离子通道;使用双电极电压钳技术研究ASIC2a的生物学特性。结果在注射ASIC2a亚基cRNA的爪蟾卵母细胞上,降低胞外液pH值可诱导出内向电流。H+诱发的ASIC2a内向电流具有稳态失活成分可被氨氯吡咪可逆性阻断,其pH50为5.12。提高胞外Ca2+浓度可降低H+诱发的电流幅度,其IC50为11.98 mmol.L-1。当细胞外液中无Na+时,H+基本上不能诱发出内向电流;当同时去除细胞外液中Na+和K+时,H+可诱发出外向电流。结论成功构建ASIC2a表达质粒;ASIC2a除了对Na+通透外,对K+也有一定的通透性,胞外Ca2+抑制ASIC2a孔道的开放。