scholarly journals Molecular Substrates Mediating Lanthanide-Evoked Neurotransmitter Release in Central Synapses

2008 ◽  
Vol 100 (4) ◽  
pp. 2089-2100 ◽  
Author(s):  
ChiHye Chung ◽  
Ferenc Deák ◽  
Ege T. Kavalali
Keyword(s):  
Neurotransmitter Release ◽  
Surface Membrane ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Protein Receptor ◽  
Rapid Action ◽  
Intracellular Ca ◽  
Synaptotagmin 1 ◽  
Molecular Substrates ◽  
Central Synapses

Noncanonical secretagogues such as hypertonicity or α-latrotoxin have been extremely informative in studying neurotransmission. Lanthanum and lanthanides can also trigger neurotransmitter release through an unknown mechanism. Here, we studied the effect of lanthanides on neurotransmission in hippocampal cultures. Application of 2 mM La3+ caused rapid and robust neurotransmitter release within seconds. In addition, transient application of La3+ uncovered a sustained facilitation of miniature neurotransmission. The response to La3+ was detectable at 2 μM and increased in a concentration-dependent manner ≤2 mM. Rapid effect of La3+ was independent of extracellular and intracellular Ca2+ and did not require La3+ entry into cells or activation of phospholipaseCβ. Synapses deficient in synaptobrevin-2, the major synaptic vesicle soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein in the brain, did not display any rapid release in response to La3+, whereas the slow facilitation of release detected after La3+ removal remained intact. In contrast, preincubation with intracellular Ca2+ chelators selectively attenuated the delayed release triggered by La3+. Moreover, synapses deficient in synaptotagmin-1 maintained a rapid response to La3+, suggesting that La3+-triggered neurotransmitter release does not require synaptotagmin-1 as a sensor. Therefore La3+ has two separate effects on synaptic transmission. For its rapid action, La3+ interacts with a target on the surface membrane, and unlike other forms of release, it triggers strictly synaptobrevin-2–dependent fusion, implying that in central synapses synaptobrevin-2 function is secretagogue specific. For the delayed action, La3+ may act intracellularly after its entry or through intracellular Ca2+ via a mechanism that does not require synaptobrevin-2.

Changes in [Ca2+]i induced by several glucose transport-enhancing stimuli in rat epitrochlearis muscle

2003 ◽  
Vol 94 (5) ◽  
pp. 1813-1820 ◽  
Author(s):  
Shin Terada ◽  
Isao Muraoka ◽  
Izumi Tabata
Keyword(s):  
Glucose Transport ◽  
Quantitative Information ◽  
Dependent Manner ◽  
Sprague Dawley ◽  
Concentration Dependent Manner ◽  
Fura 2 ◽  
Sprague Dawley Rats ◽  
Intracellular Ca ◽  
Resting Muscle ◽  
Krebs Henseleit Buffer

The purpose of the present investigation was to establish a method for estimating intracellular Ca2+ concentrations ([Ca2+]i) in isolated rat epitrochlearis muscles. Epitrochlearis muscles excised from 4-wk-old male Sprague-Dawley rats were loaded with a fluorescent Ca2+indicator, fura 2-AM, for 60–90 min at 35°C in oxygenated Krebs-Henseleit buffer. After fura 2 loading and subsequent 20-min incubation, the intensities of 500-nm fluorescence, induced by 340- and 380-nm excitation lights (Ftotal340 and Ftotal380), were measured. The fluorescences specific to fura-2 (Ffura 2340 and Ffura 2380) were calculated by subtracting the non-fura 2-specific component from Ftotal340 and Ftotal380, respectively. The ratio of Ffura 2340 to Ffura 2380 was calculated as R, and the change in the ratio from the baseline value (ΔR) was used as an index of the change in [Ca2+]i. In resting muscle, ΔR was stable for 60 min. Incubation for 20 min with caffeine (3–10 mM) significantly increased ΔR in a concentration-dependent manner. Incubation with hypoxic Krebs-Henseleit buffer for 10–60 min significantly elevated ΔR, depending on the duration of the incubation. Incubation with 50 μM N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide for 20 min significantly elevated ΔR ( P < 0.05). No significant increases in ΔR were observed during incubation for 20 min with 2 mM 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside or with 2 mU/ml insulin. These results demonstrated that, by using the fura 2-AM fluorescence method, the changes in [Ca2+]i can be monitored in the rat epitrochlearis muscle and suggest that the method can be utilized to observe quantitative information regarding [Ca2+]i that may be involved in contraction- and hypoxia-stimulated glucose transport activity in skeletal muscle.

scholarly journals Citrus bergamiaRisso Elevates Intracellular Ca2+in Human Vascular Endothelial Cells due to Release of Ca2+from Primary Intracellular Stores

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Purum Kang ◽  
Seung Ho Han ◽  
Hea Kyung Moon ◽  
Jeong-Min Lee ◽  
Hyo-Keun Kim ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Channel Blocker ◽  
Vascular Endothelial Cells ◽  
Umbilical Vein ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Concentration Dependent Manner ◽  
Carbonyl Cyanide ◽  
Intracellular Ca ◽  
Umbilical Vein Endothelial Cells

The purpose of the present study is to examine the effects of essential oil ofCitrus bergamiaRisso (bergamot, BEO) on intracellular Ca2+in human umbilical vein endothelial cells. Fura-2 fluorescence was used to examine changes in intracellular Ca2+concentration[Ca2+]i. In the presence of extracellular Ca2+, BEO increased[Ca2+]i, which was partially inhibited by a nonselective Ca2+channel blocker La3+. In Ca2+-free extracellular solutions, BEO increased[Ca2+]iin a concentration-dependent manner, suggesting that BEO mobilizes intracellular Ca2+. BEO-induced[Ca2+]iincrease was partially inhibited by a Ca2+-induced Ca2+release inhibitor dantrolene, a phospholipase C inhibitor U73122, and an inositol 1,4,5-triphosphate (IP3)-gated Ca2+channel blocker, 2-aminoethoxydiphenyl borane (2-APB). BEO also increased[Ca2+]iin the presence of carbonyl cyanide m-chlorophenylhydrazone, an inhibitor of mitochondrial Ca2+uptake. In addition, store-operated Ca2+entry (SOC) was potentiated by BEO. These results suggest that BEO mobilizes Ca2+from primary intracellular stores via Ca2+-induced and IP3-mediated Ca2+release and affect promotion of Ca2+influx, likely via an SOC mechanism.

Low [Mg2+]o induces contraction and [Ca2+]i rises in cerebral arteries: roles of Ca2+, PKC, and PI3

2000 ◽  
Vol 279 (6) ◽  
pp. H2898-H2907 ◽  
Author(s):  
Zhi-Wei Yang ◽  
Jun Wang ◽  
Tao Zheng ◽  
Bella T. Altura ◽  
Burton M. Altura
Keyword(s):  
Cerebral Arteries ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Voltage Gated ◽  
Selective Antagonist ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Intracellular Ca ◽  
Basilar Arteries ◽  
Specific Antagonist

Removal of extracellular Ca2+ concentration ([Ca2+]o) and pretreatment of canine basilar arterial rings with either an antagonist of voltage-gated Ca2+ channels (verapamil), a selective antagonist of the sarcoplasmic reticulum Ca2+ pump [thapsigargin (TSG)], caffeine plus a specific antagonist of ryanodine-sensitive Ca2+ release (ryanodine), or ad- myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]- mediated Ca2+ release antagonist (heparin) markedly attenuates low extracellular Mg2+ concentration ([Mg2+]o)-induced contractions. Low [Mg2+]o-induced contractions are significantly inhibited by pretreatment of the vessels with Gö-6976 [a protein kinase C-α (PKC-α)- and PKC-βI-selective antagonist], bisindolylmaleimide I (Bis, a specific antagonist of PKC), and wortmannin or LY-294002 [selective antagonists of phosphatidylinositol-3 kinases (PI3Ks)]. These antagonists were also found to relax arterial contractions induced by low [Mg2+]o in a concentration-dependent manner. The absence of [Ca2+]o and preincubation of the cells with verapamil, TSG, heparin, or caffeine plus ryanodine markedly attenuates the transient and sustained elevations in the intracellular Ca2+ concentration ([Ca2+]i) induced by low-[Mg2+]o medium. Low [Mg2+]o-produced increases in [Ca2+]i are also suppressed markedly in the presence of Gö-6976, Bis, wortmannin, or LY-294002. The present study suggests that both Ca2+ influx through voltage-gated Ca2+ channels and Ca2+ release from intracellular stores [both Ins(1,4,5)P3sensitive and ryanodine sensitive] play important roles in low-[Mg2+]o medium-induced contractions of isolated canine basilar arteries. Such contractions are clearly associated with activation of PKC isoforms and PI3Ks.

Comparative Effects of Bupivacaine and Ropivacaine on Intracellular Calcium Transients and Tension in Ferret Ventricular Muscle

2004 ◽  
Vol 101 (4) ◽  
pp. 888-894 ◽  
Author(s):  
Yasushi Mio ◽  
Norio Fukuda ◽  
Yoichiro Kusakari ◽  
Yoshikiyo Amaki ◽  
Yasumasa Tanifuji ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Bay K 8644 ◽  
Clinical Settings ◽  
Ca Channel ◽  
Dependent Manner ◽  
Inhibitory Effects ◽  
Concentration Dependent Manner ◽  
Intracellular Ca ◽  
Slope Difference ◽  
The Relationship

Background Recent evidence suggests that ropivacaine exerts markedly less cardiotoxicity compared with bupivacaine; however, the mechanisms are not fully understood at the molecular level. Methods Isolated ferret ventricular papillary muscles were microinjected with the Ca-binding photoprotein aequorin, and intracellular Ca transients and tension were simultaneously measured during twitch in the absence and presence of bupivacaine or ropivacaine. Results Bupivacaine and ropivacaine (10, 30, and 100 microm) reduced peak systolic [Ca]i and tension in a concentration-dependent manner. The effects were significantly greater for bupivacaine, particularly on tension (approximately twofold). The percentage reduction of tension was linearly correlated with that of [Ca]i for both anesthetics, with the slope of the relationship being approximately equal to 1.0 for ropivacaine and approximately equal to 1.3 for bupivacaine (slope difference, P &lt; 0.05), suggesting that the cardiodepressant effect of ropivacaine results predominantly from inhibition of Ca transients, whereas bupivacaine suppresses Ca transients and the reaction beyond Ca transients, i.e., myofibrillar activation, as well. BAY K 8644, a Ca channel opener, abolished the inhibitory effects of ropivacaine on Ca transients and tension, whereas BAY K 8644 only partially inhibited the effects of bupivacaine, particularly the effects on tension. Conclusion The cardiodepressant effect of bupivacaine is approximately twofold greater than that of ropivacaine. Bupivacaine suppresses Ca transients more markedly than does ropivacaine and reduces myofibrillar activation, which may at least in part underlie the greater inhibitory effect of bupivacaine on cardiac contractions. These results suggest that ropivacaine has a more favorable profile as a local anesthetic in the clinical settings.

scholarly journals Cross talk between polysulfide and nitric oxide in rat peritoneal mast cells

2016 ◽  
Vol 310 (11) ◽  
pp. C894-C902 ◽  
Author(s):  
Amira Moustafa ◽  
Yoshiaki Habara
Keyword(s):  
Nitric Oxide ◽  
Mast Cells ◽  
Ryanodine Receptor ◽  
Cross Talk ◽  
Receptor Blocker ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Peritoneal Mast Cells ◽  
Intracellular Ca ◽  
Rat Peritoneal Mast Cells

The aim of this study was to define the effects of polysulfide on intracellular Ca2+ concentration ([Ca2+]i) and the underlying machinery, especially from the hydrogen sulfide (H2S) and nitric oxide (NO) perspectives, in rat peritoneal mast cells. We found that a polysulfide donor, Na2S4, increased [Ca2+]i, which is both extracellular and intracellular Ca2+ dependent. Intracellular Ca2+ release induced by Na2S4 was attenuated by the addition of a ryanodine receptor blocker. A slow-releasing H2S donor, GYY4137, dose dependently increased [Ca2+]i that was independent from extracellular Ca2+ influx. The GYY4137-induced [Ca2+]i release was partially attenuated in the presence of the ryanodine receptor blocker. Both polysulfide and H2S donors increased the intracellular NO levels in DAF-2-loaded mast cells, which were abolished by an NO scavenger, cPTIO. Inhibition of NO synthase (NOS) significantly abolished the polysulfide- or H2S-donor-induced [Ca2+]i elevation in the absence of extracellular Ca2+. An NO donor, diethylamine (DEA) NONOate, increased [Ca2+]i in a concentration-dependent manner, in which both extracellular and intracellular Ca2+ are associated. At higher concentrations, the DEA NONOate-induced [Ca2+]i increases were attenuated in the absence of extracellular Ca2+ and by the addition of the ryanodine receptor blocker. H2S and NO dose dependently induced polysulfide production. Curiously, polysulfide, H2S, and NO donors had no effect on mast cell degranulation. Among synthases, cystathionine-γ-lyase, and neuronal NOS seemed to be the major H2S- and NO-producing synthases, respectively. These results indicate that polysulfide acts as a potential signaling molecule that regulates [Ca2+]i homeostasis in rat peritoneal mast cells via a cross talk with NO and H2S.

scholarly journals Role of store-operated Ca2+ entry in adenosine-induced vasodilatation of rat small mesenteric artery

2009 ◽  
Vol 297 (1) ◽  
pp. H347-H354 ◽  
Author(s):  
Shengpeng Wang ◽  
Yan Zhang ◽  
W. Gil Wier ◽  
Xiaojiang Yu ◽  
Ming Zhao ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Laser Scanning Confocal Microscopy ◽  
Protective Role ◽  
Dependent Manner ◽  
Resistance Arteries ◽  
Concentration Dependent Manner ◽  
Scanning Confocal Microscopy ◽  
Store Depletion ◽  
Intracellular Ca ◽  
Isolated Artery

Store-operated Ca2+ entry (SOCE) has recently been proposed to contribute to Ca2+ influx in vascular smooth muscle cells (VSMCs). Adenosine is known for its protective role against hypoxia and ischemia by increasing nutrient and oxygen supply through vasodilation. This study was designed to examine the hypothesis that SOCE have a functional role in adenosine-induced vasodilation. Small mesenteric resistance arteries and mesenteric VSMCs were obtained from rats. Isometric tensions of isolated artery rings were measured by a sensitive myograph system. Laser-scanning confocal microscopy was used to determine the intracellular Ca2+ concentration of fluo 3-loaded VSMCs. Adenosine (0.1–100 μM) relaxed artery rings that were precontracted by phenylephrine in a concentration-dependent manner. In cultured mesenteric VSMCs, passive store depletion by thapsigargin and active store depletion by phenylephrine both induced Ca2+ influx due to SOCE. Adenosine inhibited SOCE-mediated increases in cytosolic Ca2+ levels evoked by the emptying of the stores. In isolated artery rings, adenosine inhibited SOCE-induced contractions due to store depletion. A2A receptor antagonism with SCH-58261 and adenylate cyclase inhibition with SQ-22536 largely attenuated adenosine responses. The cAMP analog 8-bromo-cAMP mimicked the effects of adenosine on SOCE. Our results indicate a novel mechanism of vasodilatation by adenosine that involves regulation of SOCE through the cAMP signaling pathway due to activation of adenosine A2A receptors.

scholarly journals Triggering Apoptotic Death of Human Malignant Melanoma A375.S2 Cells by Bufalin: Involvement of Caspase Cascade-Dependent and Independent Mitochondrial Signaling Pathways

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Yu-Ping Hsiao ◽  
Chun-Shu Yu ◽  
Chien-Chih Yu ◽  
Jai-Sing Yang ◽  
Jo-Hua Chiang ◽  
...  
Keyword(s):  
Malignant Melanoma ◽  
Morphological Changes ◽  
Chromatin Condensation ◽  
Signal Pathways ◽  
Dependent Manner ◽  
S2 Cells ◽  
Concentration Dependent Manner ◽  
Human Malignant Melanoma ◽  
Intracellular Ca ◽  
Venom Glands

Bufalin was obtained from the skin and parotid venom glands of toad and has been shown to induce cytotoxic effects in various types of cancer cell lines, but there is no report to show that whether bufalin affects human skin cancer cells. The aim of this investigation was to study the effects of bufalin on human malignant melanoma A375.S2 cells and to elucidate possible mechanisms involved in induction of apoptosis. A375.S2 cells were treated with different concentrations of bufalin for a specific time period and investigated for effects on apoptotic analyses. Our results indicated that cells after exposure to bufalin significantly decreased cell viability, and induced cell morphological changes and chromatin condensation in a concentration-dependent manner. Flow cytometric assays indicated that bufalin promoted ROS productions, loss of mitochondrial membrane potential (ΔΨm), intracellular Ca2+release, and nitric oxide (NO) formations in A375.S2 cells. Additionally, the apoptotic induction of bufalin on A375.S2 cells resulted from mitochondrial dysfunction-related responses (disruption of theΔΨmand releases of cytochromec, AIF, and Endo G), and activations of caspase-3, caspase-8 and caspase-9 expressions. Based on those observations, we suggest that bufalin-triggered apoptosis in A375.S2 cells is correlated with extrinsic- and mitochondria-mediated multiple signal pathways.

scholarly journals Expression, localization, and functional role for synaptotagmins in pancreatic acinar cells

2011 ◽  
Vol 301 (2) ◽  
pp. G306-G316 ◽  
Author(s):  
Michelle A. Falkowski ◽  
Diana D. H. Thomas ◽  
Scott W. Messenger ◽  
Thomas F. Martin ◽  
Guy E. Groblewski
Keyword(s):  
Membrane Trafficking ◽  
Functional Role ◽  
Apical Membrane ◽  
Pancreatic Acinar Cells ◽  
Zymogen Granule ◽  
Pancreatic Acini ◽  
Protein Receptor ◽  
Intracellular Ca ◽  
Synaptotagmin 1 ◽  
Associated Family

Secretagogue-induced changes in intracellular Ca2+ play a pivotal role in secretion in pancreatic acini yet the molecules that respond to Ca2+ are uncertain. Zymogen granule (ZG) exocytosis is regulated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes. In nerve and endocrine cells, Ca2+-stimulated exocytosis is regulated by the SNARE-associated family of proteins termed synaptotagmins. This study examined a potential role for synaptotagmins in acinar secretion. RT-PCR revealed that synaptotagmin isoforms 1, 3, 6, and 7 are present in isolated acini. Immunoblotting and immunofluorescence using three different antibodies demonstrated synaptotagmin 1 immunoreactivity in apical cytoplasm and ZG fractions of acini, where it colocalized with vesicle-associated membrane protein 2. Synaptotagmin 3 immunoreactivity was detected in membrane fractions and colocalized with an endolysosomal marker. A potential functional role for synaptotagmin 1 in secretion was indicated by results that introduction of synaptotagmin 1 C2AB domain into permeabilized acini inhibited Ca2+-dependent exocytosis by 35%. In contrast, constructs of synaptotagmin 3 had no effect. Confirmation of these findings was achieved by incubating intact acini with an antibody specific to the intraluminal domain of synaptotagmin 1, which is externalized following exocytosis. Externalized synaptotagmin 1 was detected exclusively along the apical membrane. Treatment with CCK-8 (100 pM, 5 min) enhanced immunoreactivity by fourfold, demonstrating that synaptotagmin is inserted into the apical membrane during ZG fusion. Collectively, these data indicate that acini express synaptotagmin 1 and support that it plays a functional role in secretion whereas synaptotagmin 3 has an alternative role in endolysosomal membrane trafficking.

scholarly journals Drosophila Synaptotagmin 7 negatively regulates synaptic vesicle fusion and replenishment in a dosage-dependent manner

2020 ◽  
Author(s):  
Zhuo Guan ◽  
Mónica C. Quiñones-Frías ◽  
Yulia Akbergenova ◽  
J. Troy Littleton
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Dependent Manner ◽  
Short Term ◽  
Sensor Model ◽  
Synaptotagmin 1 ◽  
Asynchronous Release ◽  
Synaptic Vesicle Fusion

AbstractSynchronous neurotransmitter release is triggered by Ca2+ binding to the synaptic vesicle protein Synaptotagmin 1, while asynchronous fusion and short-term facilitation is hypothesized to be mediated by plasma membrane-localized Synaptotagmin 7 (SYT7). We generated mutations in Drosophila Syt7 to determine if it plays a conserved role as the Ca2+ sensor for these processes. Electrophysiology and quantal imaging revealed evoked release was elevated 2-fold. Syt7 mutants also had a larger pool of readily-releasable vesicles, faster recovery following stimulation, and robust facilitation. Syt1/Syt7 double mutants displayed more release than Syt1 mutants alone, indicating SYT7 does not mediate the residual asynchronous release remaining in the absence of SYT1. SYT7 localizes to an internal membrane tubular network within the peri-active zone, but does not enrich at release sites. These findings indicate the two Ca2+ sensor model of SYT1 and SYT7 mediating all phases of neurotransmitter release and facilitation is not applicable at Drosophila synapses.

Maitotoxin increases inositol phosphates in rat anterior pituitary cells

1991 ◽  
Vol 6 (1) ◽  
pp. 95-99 ◽  
Author(s):  
M. A. Sortino ◽  
T. M. Delahunty ◽  
T. Yasumoto ◽  
M. J. Cronin
Keyword(s):  
Anterior Pituitary ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Cell Types ◽  
Calcium Stores ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Anterior Pituitary Cells ◽  
Intracellular Ca

ABSTRACT Maitotoxin is a potent marine poison that mobilizes calcium in most vertebrate cell types and accelerates secretion from anterior pituitary cells. It is not known whether voltage-sensitive calcium channels or other mechanisms initiate the effects of maitotoxin on anterior pituitary cells. Changes in intracellular Ca2+ levels may also be achieved by releasing internal calcium stores via inositol trisphosphate (InsP3). Indeed, maitotoxin rapidly increased inositol phosphate accumulation in a concentration-dependent manner. Calcium channel antagonists such as nifedipine and verapamil did not block this response nor did calcium-mobilizing agents (BAYk8644, A23187) mimic this effect. These data suggest that the mechanism by which maitotoxin acts at the pituitary may include the activation of an enzyme that produces the calcium-mobilizing signal InsP3.

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