Photosynthesis-Dependent Extracellular Ca2+ Influx Triggers an Asexual Reproductive Cycle in the Marine Red Macroalga Porphyra yezoensis

Asexual propagation to increase the number of gametophytic clones via the growth of asexual haploid spores is a unique survival strategy found in marine multicellular algae. However, the mechanisms regulating the asexual life cycle are largely unknown. Here, factors involved in the regulation of production and discharge of asexual spores, so-called monospores, are identified in the marine red macroalga Porphyra yezoensis. First, enhanced discharge of monospores was found by incubation of gametophytes in ASPMT1, a modified version of the previously established synthetic medium ASP12. Comparison of the compositions of ASPMT1 and our standard medium, ESL, indicated that the Ca2+ concentration in ASPMT1 was three times lower than that in ESL medium. Thus, we modified ASPMT1 by increasing its Ca2+ concentration, resulting in reduction of monospore discharge. These findings demonstrate the role of reduced Ca2+ concentrations in enhancing monospore production and release. Moreover, it was also observed that initiation of asexual life cycle required illumination, was repressed by DCMU, and was induced by a Ca2+ ionophore in the dark. Taken together, these results indicate that photosynthesis-dependent Ca2+ influx triggers the asexual life cycle by promoting the production and discharge of monospores in P. yezoensis.

High-frequency repetitive transcranial magnetic stimulation promotes neural stem cell proliferation after ischemic stroke

Prolife ration of neural stem cells is crucial for promoting neuronal regeneration and repairing cerebral infarction damage.Transcranial magnetic stimulation(TMS)has recently emerged as a tool for inducing endogenous neural stem cell regeneration,but its underlying mechanisms remain unclea r In this study,we found that repetitive TMS effectively promotes the proliferation of oxygen-glucose deprived neural stem cells.Additionally,repetitive TMS reduced the volume of cerebral infa rction in a rat model of ischemic stro ke caused by middle cerebral artery occlusion,im p roved rat cognitive function,and promoted the proliferation of neural stem cells in the ischemic penumbra.RNA-sequencing found that repetitive TMS activated the Wnt signaling pathway in the ischemic penumbra of rats with cerebral ischemia.Furthermore,PCR analysis revealed that repetitive TMS promoted AKT phosphorylation,leading to an increase in mRNA levels of cell cycle-related proteins such as Cdk2 and Cdk4.This effect was also associated with activation of the glycogen synthase kinase 3β/β-catenin signaling pathway,which ultimately promotes the prolife ration of neural stem cells.Subsequently,we validated the effect of repetitive TMS on AKT phosphorylation.We found that repetitive TMS promoted Ca2+influx into neural stem cells by activating the P2 calcium channel/calmodulin pathway,thereby promoting AKT phosphorylation and activating the glycogen synthase kinase 3β/β-catenin pathway.These findings indicate that repetitive TMS can promote the proliferation of endogenous neural stem cells through a Ca2+influx-dependent phosphorylated AKT/glycogen synthase kinase 3β/β-catenin signaling pathway.This study has produced pioneering res ults on the intrinsic mechanism of repetitive TMS to promote neural function recove ry after ischemic stro ke.These results provide a stro ng scientific foundation for the clinical application of repetitive TMS.Moreover,repetitive TMS treatment may not only be an efficient and potential approach to support neurogenesis for further therapeutic applications,but also provide an effective platform for the expansion of neural stem cells.

Attenuation of nicotine-evoked Ca²⁺influx by antibody to the nicotinic acetylcholine receptor <i>α</i>3 subunits in human embryonic kidney cells

Autoantibody against neuronal nicotinic acetylcholine receptor (nAChR) α3 subunit is implicated in severe autonomic dysfunction in the patients with autoimmune autonomic ganglionopathy (AAG). Although this autoantibody has been revealed to impair fast excitatory synaptic transmission in autonomic ganglia, its precise mechanism remains unknown. Here, we show that antibody-induced reduction of cell-surface α3 subunits result in impairment of nicotine-evoked Ca2+ influx in stably transfected human embryonic kidney cells. These effects of the antibody were remarkably inhibited by interfering with the endocytic machinery at low-temperature. We conclude that reduction of nAChR in autonomic ganglia can be mediated by the endocytosis of α3 subunits, and resulted in autonomic failure in AAG patients.

川芎嗪对正常及高血压大鼠动脉平滑肌Ca^(2+)内流的动力学影响

本工作比较自发性高血压大鼠(SHR)和肾性高血压大鼠(RHR)及它们的对照动物WKY和Wistar大鼠主动脉和肠系膜动脉平滑肌Ca^(2+)内流及川芎嗪对Ca^(2+)内流的影响。结果表明高血压动物血管平滑肌(VSM)Ca^(2+)内流明显高于正常动物。体外给川芎嗪明显抑制高血压大鼠及对照动物VSMCa^(2+)内流;口饲川芎嗪,对正常动物的VSMCa^(2+)内流呈明显激活,而对高血压大鼠是明显抑制。 川芎嗪对正常及高血压动物血压无明显影响。

细胞外Ca^（2＋）内流入胞质的机制

细胞外Ｃａ２＋主要是通过电压依赖性Ｃａ２＋通道（ＶＤＣＣ）和钙池耗竭依赖性Ｃａ２＋通道（ＳＤＤＣＣ）而内流的。前者主要见于电兴奋细胞，这一过程比较清楚；后者主要见于非兴奋细胞，情况远较复杂：外来信号激活内贮钙池，钙池在释放Ｃａ２＋的同时，通过目前尚不清楚的途径将信号直接或间接传至质膜Ｇａ２＋通道，而诱发Ｃａ２＋内流。有关这方面的研究非常迅速，本文综述近两年来这方面的最新进展。

病毒巨噬细胞炎性蛋白Ⅱ N端肽调控SDF-1α/CXCR4诱导趋化机制

目的:评价病毒巨噬细胞炎性蛋白ⅡN端肽(NT21MP)是否通过干扰SDF-1α/CXCR4信号抑制人乳腺癌细胞株SKBR3细胞的趋化作用。方法:以RT-PCR和免疫组化检测SKBR3和MCF-7两种人乳腺癌细胞中CXCR4的表达;用细胞转移实验检测在NT21MP存在或缺乏的情况下SDF-1α诱导SKBR3细胞的趋化作用;以Fluo3/AM为细胞内游离钙离子的荧光指示剂,用激光扫描共聚焦显微镜测定NT21MP对SDF-1α诱导SKBR3细胞内游离钙浓度的影响;Western blot分析ERK1/2和FAK蛋白的磷酸化水平变化。结果:相对于MCF-7细胞,SKBR3细胞中CXCR4蛋白表达水平较高;经SDF-1α处理后,SKBR3的迁移能力提高,CXCR4抑制剂AMD3100可有效抑制SKBR3细胞的迁移,细胞经NT21MP预处理后,可剂量依赖性地抑制SKBR3细胞的迁移(P<0.05);NT21MP也可抑制由SDF-1α诱导的细胞内Ca2+峰值(P<0.05),而钙离子浓度升高是SKBR3细胞迁移的重要信号之一;另外,相对于阴性对照组,NT21MP也可下调SDF-1α诱导的SKBR3中信号蛋白ERK1/2和FAK的磷酸化水平(P<0.05)。结论:NT21MP可抑制SDF-1α诱导的SK-BR3细胞的迁移,可能与其上游钙离子释放和ERK1/2及FAK磷酸化阻断信号有关。

小檗碱抗富含血小板血浆凝块收缩的作用及其机制

对小檗碱抗富含血小板血浆凝块收缩的作用进行研究，结果表明①小檗碱（ＢＲ）浓度为０．２９～０．８７ｍｍｏｌ·Ｌ－１时．有非常显著的抑制凝块收缩的作用。②ＢＲ浓度为０．５～２．０ｍｍｏｌ·Ｌ－１时．对血小板ｃＡＭＰ水平无影响．提示ＢＲ抑制凝块收缩的作用与ｃＡＭＰ无关．③当外加Ｃａ２＋浓度自０增加到１１．４７ｍｍｏｌ·Ｌ时，凝块收缩率随Ｃａ２＋内流增加而上升。同样条件下．ＢＲ浓度自０增加到０．６ｍｍｏｌ·Ｌ－１时．凝块收缩率显著或非常显著地下降。提示ＢＲ抑制凝块收缩的机制可能是由于直接抑制了Ｃａ２＋内流所致。

七氟烷静吸复合麻醉减少心肌缺血再灌注损伤的作用及机制研究

目的:探究七氟烷静吸复合麻醉(IA)减少心肌缺血再灌注损伤的作用及机制。方法:选用健康雄性巴马系香猪38头,采用随机数字表法分为静脉麻醉(Ⅳ)组(n=19)、静吸复合麻醉(IA)组(n=19),Ⅳ组采用丙泊酚、舒芬太尼、维库溴铵诱导麻醉术中采用瑞芬太尼、右美托咪啶维持麻醉;IA组在Ⅳ组基础上加用七氟烷吸入式麻醉。采用分光光度法、酶联免疫吸附法及Western Blot检测两组香猪术前术后不同时期心肌组织过氧化氢酶含量、胞内Ca2+含量、血清炎性因子白细胞介素6(IL-6)、白细胞介素1β(IL-1β)、肿瘤坏死因子α(TNF-α)水平及半胱氨酸蛋白酶-3(caspase-3)、B淋巴细胞瘤-2(Bcl-2)、Bax蛋白表达水平。结果:与术前比较,Ⅳ组和IA组香猪再灌注6 h后过氧化氢酶含量明显降低,心肌细胞胞浆内Ca2+含量明显升高(P<0.05)JA组香猪在缺血1 h再灌注6 h后心肌组织过氧化氢酶含量明显低于IV组(P<0.05);两组香猪再灌注3 h、6 h后血清中炎性因子IL-6、IL-1β、TNF-α水平与术前相比明显升高(P<0.05)且IV组IL-6、IL-1β、TNF-α水平明显高于IA组(P<0.05);两组香猪再灌注6 h后caspase-3、Bax、Bcl-2蛋白水平与术前相比有显著性差异(P<0.05);IA组香猪再灌注6 h后caspase-3、Bax蛋白水平明显低于Ⅳ组,Bcl-2蛋白水平明显高于IV组(P<0.05)。结论:静吸复合麻醉可有效减少细胞自由基释放、Ca2+内流及血清炎性介质释放,并减少猪心肌细胞的凋亡。

蛇床子素对大鼠离体胸主动脉的舒张作用

目的:研究蛇床子素对大鼠胸主动脉的舒张作用并探讨其机制。方法:采用大鼠胸主动脉环张力测定法,观察蛇床子素对苯肾上腺素(PE)和氯化钾(KCl)预收缩的大鼠离体胸主动脉的舒张作用。结果:蛇床子素在不改变血管基础张力的情况下能明显抑制由PE或KCl诱导的大鼠胸主动脉环收缩,其血管舒张作用为非血管内皮依赖性。在无Ca2+溶液中,蛇床子素不能抑制咖啡因或PE诱导的细胞内钙的释放,但添加Ca2+后,蛇床子素能够抑制KCl诱导的细胞外钙内流。结论:蛇床子素的血管舒张作用是非血管内皮依赖性的,其机制可能是通过阻断血管平滑肌细胞上的钙离子通道,抑制细胞外Ca2+内流而起作用的。

维拉帕米对CVB_3感染心肌细胞Ca^(2+)内流及CVB_3-RNA含量的影响

观察了维拉帕米(Verapamil,Ver)对感染柯萨奇B_3病毒(CVB_3)的大鼠培养心肌细胞Ca^(2+)内流及CVB_3-RNA复制的影响。结果发现在感染48h后,Ver对感染细胞及正常对照的Ca^(2+)内流均有显著的抑制作用(P<0.01);若在病毒感染同时加入Ver,经48h培养后,细胞中CVB_3-RNA含量显著高于病毒对照组(P<0.05)。提示钙拮抗剂(如Ver)可减少病毒感染引起的心肌Ca^(2+)内流增加,有可能减轻感染细胞的继发性Ca^(2+)损伤;但Ver会促进病毒RNA的复制,提示在急性病毒性心肌炎临床上用Ver治疗心律失常时宜慎重。

荷叶生物碱对牛肾上腺髓质细胞儿茶酚胺分泌的影响

目的探讨荷叶生物碱对牛肾上腺髓质细胞儿茶酚胺分泌的影响。方法采用体外培养牛肾上腺髓质细胞,通过HPLC-ECD、FlexstationⅢ荧光法分别检测细胞培养液中儿茶酚胺的含量、细胞内钙含量,考察荷叶生物碱对不同刺激剂诱导的儿茶酚胺分泌的影响,以及在不同刺激剂下荷叶生物碱浓度变化对儿茶酚胺的分泌和钙流的影响。结果荷叶生物碱能明显抑制乙酰胆碱、藜芦定碱、高钾诱导的儿茶酚胺分泌(P<0.05或P<0.01),呈现剂量依赖性;且能抑制乙酰胆碱诱导的细胞外钙离子内流。结论荷叶生物碱通过烟碱型乙酰胆碱受体、电压依赖型钠离子通道、钙离子通道发挥抑制交感活性作用。

Abnormal mitochondrial function impairs calcium influx in diabetic mouse pancreatic beta cells

Background Abnormal insulin secretion of pancreatic beta cells is now regarded as the more primary defect than the insulin function in the etiology of type 2 diabetes.Previous studies found impaired mitochondrial function and impaired Ca2＋ influx in beta cells in diabetic patients and animal models,suggesting a role for these processes in proper insulin secretion.The aim of this study was to investigate the detailed relationship of mitochondrial function,Ca2＋ influx,and defective insulin secretion.Methods We investigated mitochondrial function and morphology in pancreatic beta cell of diabetic KK-Ay mice and C57BL/6J mice.Two types of Ca2＋ channel activities,L-type and store-operated Ca2＋ （SOC）,were evaluated using whole-cell patch-clamp recording.The glucose induced Ca2＋ influx was measured by a non-invasive micro-test technique （NMT）.Results Mitochondria in KK-Ay mice pancreatic beta cells were swollen with disordered cristae,and mitochondrial function decreased compared with C57BL/6J mice.Ca2＋ channel activity was increased and glucose induced Ca2＋ influx was impaired,but could be recovered by genipin.Conclusion Defective mitochondrial function in diabetic mice pancreatic beta cells is a key cause of abnormal insulin secretion by altering Ca2＋ influx,but not via Ca2＋ channel activity.

Effects of La^(3+) and Gd^(3+) on Ca^(2+) influx in rat hepatoma H-35 cells

Effects of La93+) and Gd3+ on Ca2+ influx were investigated in rat hepatoma H-35 cells by measuring the initial rate of45Ca2+ uptake. It was found that the maximum initial rate of Ca2+ uptake was increased six- to ten-fold at low concentrations of La3+ and Gd3+. Kinetic analyses by measuring the initial rate of Ca2+ influx at different external Ca2+ concentrations indicated the existence of two intracellular exchangeable components in the basal Ca2+ system, with low and high affinities for Ca2+,and only one class of Ca2+ binding sites was observed in the La3+- or Gd3+-treated cells. For high affinity, La3+ and Gd3+ increased both kinetic parameters Km and V(max of basal Ca2+ influx. La3+ and Gd3+ compete directly with Ca2+ for Ca2+ binding site for low affinity. The kinetics is competitive.

Effect of Astragalus Membranaceus on Ca￣(2＋）Influx and CVB3 RNA Replication in Cultured Neonatal Rat Heart C

Here was investigated the effect of Radix Astragalus Membranaceus IAM) on Caz+ influxacross the myocardial plasma membrane and coxsackie virus B3 ( CVB3 ) -RNA replication in cultured neonatalrat heart cells infected with CVB3 . It was found that the Oa2+ intlux could be inhibited signiticantly by AM bothin heart cells intected with CVB3 for 48 hours and in normal control heart cells. In addition. the Caz+ intluxand the amounts of CVB3-RNA in rnyocytes simultaneously intected with CVB3 and treated with AM for 48hours were statistically decreased compared with that in CVB3-infected contrOI cells. These phenomena sug-gested that AM could exert the effects of decreasing the secondary Ca2+ damages, irnproving the abnormalmyocardial electric activity and inhibiting replication of CVB3-RNA in myocardium. Thus, it is a rationalchoice to treat patients with AM in viral myocarditis.

柚皮苷对豚鼠离体气管平滑肌作用的机制研究

目的考察柚皮苷对正常及多种致痉剂诱导的豚鼠气管平滑肌收缩功能的影响及其作用机制。方法采用离体气管恒温灌流的方法,取豚鼠气管,在K-H液中制备豚鼠离体气管环,在其静息张力状态下以及用乙酰胆碱（Ach）、组胺（His）、氯化钙（Ca Cl2）、无钙时Ach诱导细胞内钙释放和高钙时诱发细胞外钙内流条件下,通过BL-420S生物机能实验系统测定其张力的变化,考察柚皮苷对离体豚鼠气管平滑肌张力的影响。结果柚皮苷低剂量浓度（0.0172~0.5504）mmol·L^-1时,对静息状态下的豚鼠离体气管平滑肌有一定的收缩作用,高剂量浓度（0.5504~1.3780）mmol·L^-1时舒张气管平滑肌,且呈剂量依赖性;使致痉剂Ach、His、Ca Cl2收缩豚鼠离体气管平滑肌的量效曲线非平行性右移,最大效应降低;抑制加入高钙后引发细胞外钙内流导致的收缩。结论柚皮苷舒张气管平滑肌作用机制可能与抑制豚鼠气管平滑肌上M受体、H1受体和阻断Ca2＋通道从而抑制细胞Ca2＋内流有关。

胡颓子叶对豚鼠离体气管平滑肌收缩功能的影响

目的研究胡颓子叶乙醇提取物正丁醇部位(胡颓子叶正丁醇部位)对正常及多种致痉剂诱导的豚鼠气管平滑肌收缩功能的影响。方法制备豚鼠离体气管平滑肌螺旋条,在其正常状态下以及用乙酰胆碱、组胺、氯化钾、无钙下乙酰胆碱诱导细胞内钙释放和高钙下诱发细胞外钙内流条件下,观察胡颓子叶正丁醇部位对离体气管张力的影响。结果胡颓子叶正丁醇部位对静息状态下的豚鼠离体气管平滑肌有明显的舒张作用,使乙酰胆碱和组胺的量效曲线发生明显右移,抑制加入高钾或高钙后引发细胞外钙内流导致的收缩。结论胡颓子叶正丁醇部位能明显抑制正常状态及多种致痉剂诱发的豚鼠气管平滑肌收缩。