Mechanical strain-induced Ca2+waves are propagated via ATP release and purinergic receptor activation

2000 ◽  
Vol 279 (2) ◽  
pp. C295-C307 ◽  
Author(s):  
H. Sauer ◽  
J. Hescheler ◽  
M. Wartenberg
Keyword(s):  
Gap Junctions ◽  
Purinergic Receptor ◽  
Mechanical Strain ◽  
Atp Release ◽  
Anion Channel ◽  
Receptor Activation ◽  
Disulfonic Acid ◽  
Channel Blockers ◽  
Junctional Coupling ◽  
Intracellular Ca

Mechanical strain applied to prostate cancer cells induced an intracellular Ca2+ (Cai 2+) wave spreading with a velocity of 15 μm/s. Cai 2+ waves were not dependent on extracellular Ca2+ and membrane potential because propagation was unaffected in high-K+ and Ca2+-free solution. Waves did not depend on the cytoskeleton or gap junctions because cytochalasin B and nocodazole, which disrupt microfilaments and microtubules, respectively, and 1-heptanol, which uncouples gap junctions, were without effects. Fluorescence recovery after photobleaching experiments revealed an absence of gap junctional coupling. Cai 2+ waves were inhibited by the purinergic receptor antagonists basilen blue and suramin; by pretreatment with ATP, UTP, ADP, UDP, 2-methylthio-ATP, and benzoylbenzoyl-ATP; after depletion of ATP by 2-deoxyglucose; and after ATP scavenging by apyrase. Waves were abolished by the anion channel inhibitors 5-nitro-2-(3-phenylpropylamino)benzoic acid, tamoxifen, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid, niflumic acid, and gadolinium. ATP release following strain was significantly inhibited by anion channel blockers. Hence, ATP is secreted via mechanosensitive anion channels and activates purinergic receptors on the same cell or neighboring cells in an autocrine and paracrine manner, thus leading to Cai 2+ wave propagation.

scholarly journals The DC electrical-field-induced Ca2+ response and growth stimulation of multicellular tumor spheroids are mediated by ATP release and purinergic receptor stimulation

2002 ◽  
Vol 115 (16) ◽  
pp. 3265-3273 ◽  
Author(s):  
Heinrich Sauer ◽  
Ramona Stanelle ◽  
Jürgen Hescheler ◽  
Maria Wartenberg
Keyword(s):  
Purinergic Receptor ◽  
Atp Release ◽  
Anion Channel ◽  
Growth Stimulation ◽  
Channel Blockers ◽  
Multicellular Tumor Spheroids ◽  
Tumor Spheroids ◽  
Electrical Field ◽  
Dependent Signal ◽  
Stimulation Of

It has been demonstrated that adenosine 5′-triphosphate (ATP) is actively secreted by cells, thereby eliciting Ca2+-dependent signal transduction cascades in an autocrine and paracrine manner. In the present study the effects of direct current (DC) electrical fields on ATP release, the intracellular Ca2+ concentration [Ca2+]i and growth of multicellular prostate tumor spheroids were investigated. Treatment of multicellular tumor spheroids by a single DC electrical field pulse with a field strength of 750 Vm-1 for 60 seconds resulted in a transient Ca2+ response, activation of c-Fos and growth stimulation. The initial [Ca2+]i signal was elicited at the anode-facing side of the spheroid and spread with a velocity of approximately 12 μm per second across the spheroid surface. The electrical-field-evoked Ca2+ response as well as c-Fos activation and growth stimulation of tumor spheroids were inhibited by pretreatment with the anion channel blockers NPPB, niflumic acid and tamoxifen. Furthermore, the Ca2+ response elicited by electrical field treatment was abolished following purinergic receptor desensitivation by repetitive treatment of tumor spheroids with ATP and pretreatment with the purinergic receptor antagonist suramin as well as with apyrase. Electrical field treatment of tumor spheroids resulted in release of ATP into the supernatant as evaluated by luciferin/luciferase bioluminescence. ATP release was efficiently inhibited in the presence of anion channel blockers. Our data suggest that electrical field treatment of multicellular tumor spheroids results in ATP release, which concomitantly activates purinergic receptors, elicits a Ca2+ wave spreading through the tumor spheroid tissue and stimulates tumor growth.

ATP potently modulates anion channel-mediated excitatory amino acid release from cultured astrocytes

2002 ◽  
Vol 283 (2) ◽  
pp. C569-C578 ◽  
Author(s):  
Alexander A. Mongin ◽  
Harold K. Kimelberg
Keyword(s):  
Amino Acid ◽  
Excitatory Amino Acid ◽  
Atp Release ◽  
Anion Channel ◽  
P2y Receptors ◽  
Cell Swelling ◽  
Channel Blockers ◽  
Medium Osmolarity ◽  
Subsequent Activation

Volume-dependent ATP release and subsequent activation of purinergic P2Y receptors have been implicated as an autocrine mechanism triggering activation of volume-regulated anion channels (VRACs) in hepatoma cells. In the brain ATP is released by both neurons and astrocytes and participates in intercellular communication. We explored whether ATP triggers or modulates the release of excitatory amino acid (EAAs) via VRACs in astrocytes in primary culture. Under basal conditions exogenous ATP (10 μM) activated a small EAA release in 70–80% of the cultures tested. In both moderately (5% reduction of medium osmolarity) and substantially (35% reduction of medium osmolarity) swollen astrocytes, exogenous ATP greatly potentiated EAA release. The effects of ATP were mimicked by P2Y agonists and eliminated by P2Y antagonists or the ATP scavenger apyrase. In contrast, the same pharmacological maneuvers did not inhibit volume-dependent EAA release in the absence of exogenous ATP, ruling out a requirement of autocrine ATP release for VRAC activation. The ATP effect in nonswollen and moderately swollen cells was eliminated by a 5–10% increase in medium osmolarity or by anion channel blockers but was insensitive to tetanus toxin pretreatment, further supporting VRAC involvement. Our data suggest that in astrocytes ATP does not trigger EAA release itself but acts synergistically with cell swelling. Moderate cell swelling and ATP may serve as two cooperative signals in bidirectional neuron-astrocyte communication in vivo.

scholarly journals Simulation of P2X-mediated calcium signaling in microglia

2018 ◽  
Author(s):  
Ben Chun ◽  
Bradley D. Stewart ◽  
Darin Vaughan ◽  
Adam D. Bachstetter ◽  
Peter M. Kekenes-Huskey
Keyword(s):  
Computational Model ◽  
Purinergic Receptor ◽  
Receptor Activation ◽  
Quantitative Model ◽  
Published Data ◽  
Transcriptional Responses ◽  
Extracellular Adenosine ◽  
Wide Range ◽  
Intracellular Ca

AbstractMicroglia function is orchestrated through highly-coupled signaling pathways that depend on calcium (Ca2+). In response to extracellular adenosine triphosphate (ATP), transient increases in intracellular Ca2+ driven through the activation of purinergic receptors, P2X and P2Y, are sufficient to promote cytokine synthesis and potentially their release. While steps comprising the pathways bridging purinergic receptor activation with transcriptional responses have been probed in great detail, a quantitative model for how these steps collectively control cytokine production has not been established. Here we developed a minimal computational model that quantitatively links extracellular stimulation of two prominent ionotropic puriner-gic receptors, P2X4 and P2X7, with the graded production of a gene product, namely the tumor necrosis factor α (TNFα) cytokine. In addition to Ca2+ handling mechanisms common to eukaryotic cells, our model includes microglia-specific processes including ATP-dependent P2X4 and P2X7 activation, activation of NFAT transcription factors, and TNFα production. Parameters for this model were optimized to reproduce published data for these processes, where available. With this model, we determined the propensity for TNFα production in microglia, subject to a wide range of ATP exposure amplitudes, frequencies and durations that the cells could encounter in vivo. Furthermore, we have investigated the extent to which modulation of the signal transduction pathways influence TNFα production. Our key findings are that TNFα production via P2X4 is maximized at low ATP when subject to high frequency ATP stimulation, whereas P2X7 contributes most significantly at millimolar ATPranges. Given that Ca2+ homeostasis in microglia is profoundly important to its function, this computational model provides a quantitative framework to explore hypotheses pertaining to microglial physiology.

Anion channel blockers inhibit swelling-activated anion, cation, and nonelectrolyte transport in HeLa cells

1996 ◽  
Vol 271 (2) ◽  
pp. C579-C588 ◽  
Author(s):  
J. A. Hall ◽  
J. Kirk ◽  
J. R. Potts ◽  
C. Rae ◽  
K. Kirk
Keyword(s):  
Hela Cells ◽  
Anion Channel ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Channel Blockers ◽  
Influx Rate ◽  
Cation Permeability ◽  
Transport Component ◽  
Selective Channel ◽  
Substrate Concentrations

The effect of osmotic cell swelling on the permeability of HeLa cells to a range of structurally unrelated solutes including taurine, sorbitol, thymidine, choline, and K+ (96Rb+) was investigated. For each solute tested, reduction in the osmolality of the medium from 300 to 200 mosmol/kgH2O caused a significant increase in the unidirectional influx rate. In each case, the osmotically activated transport component was nonsaturable up to external substrate concentrations of 50 mM. Inhibitors of the swelling-activated anion channel of HeLa cells [quinine, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, niflumate, 1,9-dideoxyforskolin, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), and tamoxifen] blocked the osmotically activated influx of each of the different substrates tested, as well as the osmotically activated efflux of taurine and I-. Tamoxifen and NPPB were similarly effective at blocking the osmotically activated efflux of 96Rb+. The simplest of several hypotheses consistent with the data is that the osmotically activated transport of the different solutes tested here is via a swelling-activated anion-selective channel that has a significant cation permeability and a minimum pore diameter of 8-9 A.

Swelling-activated efflux of taurine and other organic osmolytes in endothelial cells

1997 ◽  
Vol 273 (1) ◽  
pp. C214-C222 ◽  
Author(s):  
V. G. Manolopoulos ◽  
T. Voets ◽  
P. E. Declercq ◽  
G. Droogmans ◽  
B. Nilius
Keyword(s):  
Endothelial Cells ◽  
Anion Channel ◽  
Disulfonic Acid ◽  
Channel Blockers ◽  
Organic Osmolytes ◽  
Dependent Manner ◽  
Anion Channels ◽  
Whole Cell Patch Clamp ◽  
Osmolyte Efflux ◽  
Dose Dependent

We used a combined biochemical, pharmacological, and electrophysiological approach to study the effects of hyposmotic swelling on organic osmolyte efflux in endothelial cells (EC). In [3H]taurine-loaded monolayers of calf pulmonary artery EC (CPAEC), hyposmolality activated time- and dose-dependent effluxes of [3H]taurine. Swelling-activated [3H]taurine efflux (Jtau swell)in CPAEC was inhibited by the anion channel blockers tamoxifen, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), fenamates, and also quinine (in a pH-dependent manner), ATP, and the phospholipase A2 inhibitor 4-bromophenacyl bromide. In contrast, Jtau swell was partly or totally insensitive to bumetanide, forskolin, phorbol 12-myristate 13-acetate, and staurosporine. Swelling also activated myo-[3H]inositol efflux that was blocked by tamoxifen, NPPB, DIDS, and niflumic acid. Moreover, the cellular content of taurine and other amino acids was significantly reduced in osmotically activated CPAEC. Finally, in whole cell patch-clamp experiments, taurine, glycine, aspartate, and glutamate exhibited significant permeability for swelling-activated anion channels. In conclusion, hyposmotic swelling activates efflux of taurine and other organic osmolytes in EC. In addition, our results suggest that anion channels may provide a pathway for swelling-activated efflux of organic osmolytes in EC.

scholarly journals Histamine Induces ATP Release from Human Subcutaneous Fibroblasts, via Pannexin-1 Hemichannels, Leading to Ca2+ Mobilization and Cell Proliferation

2013 ◽  
Vol 288 (38) ◽  
pp. 27571-27583 ◽  
Author(s):  
Ana Rita Pinheiro ◽  
Diogo Paramos-de-Carvalho ◽  
Mariana Certal ◽  
Maria Adelina Costa ◽  
Cristina Costa ◽  
...  
Keyword(s):  
Cell Growth ◽  
Pyridoxal Phosphate ◽  
Type I Collagen ◽  
Prolonged Exposure ◽  
Atp Release ◽  
Receptor Activation ◽  
Disulfonic Acid ◽  
Type I ◽  
Reactive Blue 2 ◽  
Pannexin 1

Changes in the regulation of connective tissue ATP-mediated mechano-transduction and remodeling may be an important link to the pathogenesis of chronic pain. It has been demonstrated that mast cell-derived histamine plays an important role in painful fibrotic diseases. Here we analyzed the involvement of ATP in the response of human subcutaneous fibroblasts to histamine. Acute histamine application caused a rise in intracellular Ca2+ ([Ca2+]i) and ATP release from human subcutaneous fibroblasts via H1 receptor activation. Histamine-induced [Ca2+]i rise was partially attenuated by apyrase, an enzyme that inactivates extracellular ATP, and by blocking P2 purinoceptors with pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt and reactive blue 2. [Ca2+]i accumulation caused by histamine was also reduced upon blocking pannexin-1 hemichannels with 10Panx, probenecid, or carbenoxolone but not when connexin hemichannels were inhibited with mefloquine or 2-octanol. Brefeldin A, an inhibitor of vesicular exocytosis, also did not block histamine-induced [Ca2+]i mobilization. Prolonged exposure of human subcutaneous fibroblast cultures to histamine favored cell growth and type I collagen synthesis via the activation of H1 receptor. This effect was mimicked by ATP and its metabolite, ADP, whereas the selective P2Y1 receptor antagonist, MRS2179, partially attenuated histamine-induced cell growth and type I collagen production. Expression of pannexin-1 and ADP-sensitive P2Y1 receptor on human subcutaneous fibroblasts was confirmed by immunofluorescence confocal microscopy and Western blot analysis. In conclusion, histamine induces ATP release from human subcutaneous fibroblasts, via pannexin-1 hemichannels, leading to [Ca2+]i mobilization and cell growth through the cooperation of H1 and P2 (probably P2Y1) receptors.

Involvement of Na+/Ca2+ exchanger in catecholamine-induced increase in intracellular calcium in cardiomyocytes

2006 ◽  
Vol 290 (1) ◽  
pp. H373-H380 ◽  
Author(s):  
Harjot K. Saini ◽  
Onkar N. Tripathi ◽  
Shetuan Zhang ◽  
Vijayan Elimban ◽  
Naranjan S. Dhalla
Keyword(s):  
Purinergic Receptor ◽  
Cyclopiazonic Acid ◽  
Channel Blockers ◽  
Inhibitory Effects ◽  
Inotropic Action ◽  
Rat Cardiomyocytes ◽  
Isolated Hearts ◽  
Adrenoceptor Agonist ◽  
Significant Depression ◽  
Intracellular Ca

Although sarcolemmal (SL) Na+/Ca2+ exchanger is known to regulate the intracellular Ca2+ concentration ([Ca2+]i), its involvement in catecholamine-induced increase in [Ca2+]i is not fully understood. To gain some information in this regard, isolated rat cardiomyocytes were treated with different agents, which are known to modify Ca2+ movements, in the absence or presence of a β-adrenoceptor agonist, isoproterenol, and [Ca2+]i in cardiomyocytes was determined spectrofluorometrically with fura-2 AM. Treatment with isoproterenol did not alter [Ca2+]i in quiescent cardiomyocytes, whereas the ATP (purinergic receptor agonist)-induced increase in [Ca2+]i was significantly potentiated by isoproterenol. Unlike ryanodine and cyclopiazonic acid, which affect the sarcoplasmic reticulum function, SL L-type Ca2+ channel blockers verapamil and diltiazem, as well as a SL Ca2+-pump inhibitor, vanadate, caused a significant depression in the isoproterenol-induced increase in [Ca2+]i. The SL Na+/Ca2+ exchange blockers amiloride, Ni2+, and KB-R7943 also attenuated the isoproterenol-mediated increase in [Ca2+]i. Combination of KB-R7943 and verapamil showed additive inhibitory effects on the isoproterenol-induced increase in [Ca2+]i. The isoproterenol-induced increase in [Ca2+]i in KCl-depolarized cardiomyocytes was augmented by low Na+; this augmentation was significantly depressed by treatment with KB-R7943. The positive inotropic action of isoproterenol in isolated hearts was also reduced by KB-R7943. These data suggest that in addition to SL L-type Ca2+ channels, SL Na+/Ca2+ exchanger seems to play an important role in catecholamine-induced increase in [Ca2+]i in cardiomyocytes.

Induction of erythrocyte microvesicles by Escherichia Coli Alpha hemolysin

2019 ◽  
Vol 476 (22) ◽  
pp. 3455-3473
Author(s):  
Karen Strack ◽  
Natalia Lauri ◽  
Sabina María Maté ◽  
Andrés Saralegui ◽  
Carlos Muñoz-Garay ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Intracellular Calcium ◽  
Purinergic Receptor ◽  
Atp Release ◽  
Receptor Activation ◽  
Erythrocyte Membranes ◽  
Protective Mechanism ◽  
Alpha Hemolysin ◽  
Outer Leaflet ◽  
Spread Of Infection

Alpha hemolysin (HlyA) is the major virulence factor of uropathogenic Escherichia coli (UPEC) strains. Once in circulation, a low concentration of the toxin induces an increase in intracellular calcium that activates calpains — which proteolyse cytoskeleton proteins — and also favours the exposure of phosphatidylserine (PS) in the outer leaflet of erythrocyte membranes. All these events are considered part of eryptosis, as well as the delivery of microvesicles (MVs). Within this context, we studied the delivery of MVs by erythrocytes treated with sublytic concentrations of HlyA and demonstrated that HlyA-treated erythrocytes secrete MVs of diameter ∼200 nm containing HlyA and PS by a mechanism involving an increment of intracellular calcium concentration and purinergic receptor activation. Despite the presence of toxin in their membrane, HlyA-MVs are not hemolytically active and do not induce ATP release in untreated erythrocytes, thus suggesting that the delivery of HlyA-MVs might act as a protective mechanism on the part of erythrocytes that removes the toxin from the membrane to prevent the spread of infection. Although erythrocytes have been found to eliminate denatured hemoglobin and several membrane proteins by shedding MVs, the present work has revealed for the first time that an exogenous protein, such as a toxin, is eliminated by this process. This finding sheds light on the mechanism of action of the toxin and serves to further elucidate the consequences of UPEC infection in patients exhibiting HlyA-related diseases.

scholarly journals Increases in endothelial Ca2+ activate KCa channels and elicit EDHF-type arteriolar dilation via gap junctions

2002 ◽  
Vol 282 (5) ◽  
pp. H1760-H1767 ◽  
Author(s):  
Zoltan Ungvari ◽  
Anna Csiszar ◽  
Akos Koller
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Gap Junctions ◽  
Palmitoleic Acid ◽  
Gracilis Muscle ◽  
Channel Blockers ◽  
Tetraacetic Acid ◽  
Kca Channels ◽  
Intracellular Ca ◽  
Coupling Time

In skeletal muscle arterioles, the pathway leading to non-nitric oxide (NO), non-prostaglandin-mediated endothelium-derived hyperpolarizing factor (EDHF)-type dilations is not well characterized. To elucidate some of the steps in this process, simultaneous changes in endothelial intracellular Ca2+ concentration ([Ca2+]i) and the diameter of rat gracilis muscle arterioles (∼60 μm) to acetylcholine (ACh) were measured by fura 2 microfluorimetry (in the absence of NO and prostaglandins). ACh elicited rapid increases in endothelial [Ca2+]i (101 ± 7%), followed by substantial dilations (73 ± 2%, coupling time: 1.3 ± 0.2 s) that were prevented by endothelial loading of an intracellular Ca2+ chelator [1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid]. Arteriolar dilations to ACh were also inhibited by intraluminal administration of the Ca2+-activated K+ (KCa) channel blockers charybdotoxin plus apamin or by palmitoleic acid, an uncoupler of myoendothelial gap junctions without affecting changes in endothelial [Ca2+]i. The presence of large conductance KCa channels on arteriolar endothelial cells was demonstrated with immunohistochemisty. We propose that in skeletal muscle arterioles, EDHF-type mediation is evoked by an increase in endothelial [Ca2+]i, which by activating endothelial KCa channels elicits hyperpolarization that is conducted via myoendothelial gap junctions to the smooth muscle resulting in decreases in [Ca2+]i and consequently dilation.

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