scholarly journals Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores

2011 ◽  
Vol 301 (3) ◽  
pp. C679-C686 ◽  
Author(s):  
Peter Sobolewski ◽  
Judith Kandel ◽  
Alexandra L. Klinger ◽  
David M. Eckmann
Keyword(s):  
Endothelial Cells ◽  
Intracellular Calcium ◽  
Calcium Release ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Calcium Transient ◽  
Epifluorescence Microscopy ◽  
Transient Receptor Potential Vanilloid ◽  
Calcium Stores ◽  
Air Bubble

Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50–150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway.

scholarly journals PKCα mediates acetylcholine-induced activation of TRPV4-dependent calcium influx in endothelial cells

2011 ◽  
Vol 301 (3) ◽  
pp. H757-H765 ◽  
Author(s):  
Ravi K. Adapala ◽  
Phani K. Talasila ◽  
Ian N. Bratz ◽  
David X. Zhang ◽  
Makoto Suzuki ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Calcium Release ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Specific Inhibitor ◽  
Receptor Potential ◽  
Cyclic Stretch ◽  
Mesenteric Arteries ◽  
Transient Receptor Potential Vanilloid

Transient receptor potential vanilloid channel 4 (TRPV4) is a polymodally activated nonselective cationic channel implicated in the regulation of vasodilation and hypertension. We and others have recently shown that cyclic stretch and shear stress activate TRPV4-mediated calcium influx in endothelial cells (EC). In addition to the mechanical forces, acetylcholine (ACh) was shown to activate TRPV4-mediated calcium influx in endothelial cells, which is important for nitric oxide-dependent vasodilation. However, the molecular mechanism through which ACh activates TRPV4 is not known. Here, we show that ACh-induced calcium influx and endothelial nitric oxide synthase (eNOS) phosphorylation but not calcium release from intracellular stores is inhibited by a specific TRPV4 antagonist, AB-159908. Importantly, activation of store-operated calcium influx was not altered in the TRPV4 null EC, suggesting that TRPV4-dependent calcium influx is mediated through a receptor-operated pathway. Furthermore, we found that ACh treatment activated protein kinase C (PKC) α, and inhibition of PKCα activity by the specific inhibitor Go-6976, or expression of a kinase-dead mutant of PKCα but not PKCε or downregulation of PKCα expression by chronic 12- O-tetradecanoylphorbol-13-acetate treatment, completely abolished ACh-induced calcium influx. Finally, we found that ACh-induced vasodilation was inhibited by the PKCα inhibitor Go-6976 in small mesenteric arteries from wild-type mice, but not in TRPV4 null mice. Taken together, these findings demonstrate, for the first time, that a specific isoform of PKC, PKCα, mediates agonist-induced receptor-mediated TRPV4 activation in endothelial cells.

scholarly journals Elucidation of a TRPC6-TRPC5 Channel Cascade That Restricts Endothelial Cell Movement

2008 ◽  
Vol 19 (8) ◽  
pp. 3203-3211 ◽  
Author(s):  
Pinaki Chaudhuri ◽  
Scott M. Colles ◽  
Manjunatha Bhat ◽  
David R. Van Wagoner ◽  
Lutz Birnbaumer ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Cell Movement ◽  
Receptor Potential ◽  
Receptor Activation ◽  
Calcium Stores ◽  
Trpc Channels ◽  
Transient Receptor

Canonical transient receptor potential (TRPC) channels are opened by classical signal transduction events initiated by receptor activation or depletion of intracellular calcium stores. Here, we report a novel mechanism for opening TRPC channels in which TRPC6 activation initiates a cascade resulting in TRPC5 translocation. When endothelial cells (ECs) are incubated in lysophosphatidylcholine (lysoPC), rapid translocation of TRPC6 initiates calcium influx that results in externalization of TRPC5. Activation of this TRPC6–5 cascade causes a prolonged increase in intracellular calcium concentration ([Ca2+]i) that inhibits EC movement. When TRPC5 is down-regulated with siRNA, the lysoPC-induced rise in [Ca2+]i is shortened and the inhibition of EC migration is lessened. When TRPC6 is down-regulated or EC from TRPC6−/− mice are studied, lysoPC has minimal effect on [Ca2+]i and EC migration. In addition, TRPC5 is not externalized in response to lysoPC, supporting the dependence of TRPC5 translocation on the opening of TRPC6 channels. Activation of this novel TRPC channel cascade by lysoPC, resulting in the inhibition of EC migration, could adversely impact on EC healing in atherosclerotic arteries where lysoPC is abundant.

scholarly journals Hydrogen peroxide-induced calcium influx in lung microvascular endothelial cells involves TRPV4

2015 ◽  
Vol 309 (12) ◽  
pp. L1467-L1477 ◽  
Author(s):  
Karthik Suresh ◽  
Laura Servinsky ◽  
Jose Reyes ◽  
Syeda Baksh ◽  
Clark Undem ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Endothelial Cells ◽  
Transient Receptor Potential ◽  
Kinase Inhibitor ◽  
Calcium Influx ◽  
Microvascular Endothelial Cells ◽  
Transient Receptor Potential Vanilloid ◽  
Src Family Kinase ◽  
Microvascular Endothelial ◽  
Pharmacologic Inhibition

In acute respiratory distress syndrome, both reactive oxygen species (ROS) and increased intracellular calcium ([Ca2+]i) are thought to play important roles in promoting endothelial paracellular permeability, but the mechanisms linking ROS and [Ca2+]i in microvascular endothelial cells are not known. In this study, we assessed the effect of hydrogen peroxide (H2O2) on [Ca2+]i in mouse and human lung microvascular endothelial cells (MLMVEC and HLMVEC, respectively). We found that in both MLMVECs and HLMVECs, exogenously applied H2O2 increased [Ca2+]i through Ca2+ influx and that pharmacologic inhibition of the calcium channel transient receptor potential vanilloid 4 (TRPV4) attenuated the H2O2-induced Ca2+ influx. Additionally, knockdown of TRPV4 in HLMVEC also attenuated calcium influx following H2O2 challenge. Administration of H2O2 or TRPV4 agonists decreased transmembrane electrical resistance (TER), suggesting increased barrier permeability. To explore the regulatory mechanisms underlying TRPV4 activation by ROS, we examined H2O2-induced Ca2+ influx in MLMVECs and HLMVECs with either genetic deletion, silencing, or pharmacologic inhibition of Fyn, a Src family kinase. In both MLMVECs derived from mice deficient for Fyn and HLMVECs treated with either siRNA targeted to Fyn or the Src family kinase inhibitor SU-6656 for 24 or 48 h, the H2O2-induced Ca2+ influx was attenuated. Treatment with SU-6656 decreased the levels of phosphorylated, but not total, TRPV4 protein and had no effect on TRPV4 response to the external agonist, GSK1016790A. In conclusion, our data suggest that application of exogenous H2O2 increases [Ca2+]i and decreases TER in microvascular endothelial cells via activation of TRPV4 through a mechanism that requires the Src kinase Fyn.

scholarly journals Genetic ablation of calcium-independent phospholipase A2β causes hypercontractility and markedly attenuates endothelium-dependent relaxation to acetylcholine

2010 ◽  
Vol 298 (6) ◽  
pp. H2208-H2220 ◽  
Author(s):  
Hans H. Dietrich ◽  
Dana R. Abendschein ◽  
Sung Ho Moon ◽  
Neema Nayeb-Hashemi ◽  
David J. Mancuso ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Intracellular Calcium ◽  
Calcium Release ◽  
Calcium Influx ◽  
Extracellular Calcium ◽  
Genetic Ablation ◽  
Vasomotor Function ◽  
Intracellular Calcium Release

Activation of phospholipases leads to the release of arachidonic acid and lysophospholipids that play prominent roles in regulating vasomotor tone. To identify the role of calcium-independent phospholipase A2β (iPLA2β) in vasomotor function, we measured vascular responses to phenylephrine (PE) and ACh in mesenteric arterioles from wild-type (WT; iPLA2β+/+) mice and those lacking the β-isoform (iPLA2β−/−) both ex vivo and in vivo. Vessels isolated from iPLA2β−/− mice demonstrated increased constriction to PE, despite lower basal smooth muscle calcium levels, and decreased vasodilation to ACh compared with iPLA2β+/+ mice. PE constriction resulted in initial intracellular calcium release with subsequent steady-state constriction that depended on extracellular calcium influx. Endothelial denudation had no effect on vessel tone or PE-induced constriction although the dilation to ACh was significantly reduced in iPLA2β+/+ vessels. In contrast, vessels from iPLA2β−/− constricted by 54% after denudation, indicating smooth muscle hypercontractility. In vivo, blood pressure, resting vessel diameter, and constriction of mesenteric vessels to PE were not different in iPLA2β−/− vessels compared with WT mouse vessels. However, relaxation after ACh administration in situ was attenuated, indicating an endothelial inability to induce dilation in response to ACh. In cultured endothelial cells, inhibition of iPLA2β with ( S)-(E)-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2 H-pyran-2-one (BEL) decreased endothelial nitric oxide synthase phosphorylation and reduced endothelial agonist-induced intracellular calcium release as well as extracellular calcium influx. We conclude that iPLA2β is an important mediator of vascular relaxation and intracellular calcium homeostasis in both smooth muscle and endothelial cells and that ablation of iPLA2β causes agonist-induced smooth muscle hypercontractility and reduced agonist-induced endothelial dilation.

scholarly journals Junctate is a key element in calcium entry induced by activation of InsP3 receptors and/or calcium store depletion

2004 ◽  
Vol 166 (4) ◽  
pp. 537-548 ◽  
Author(s):  
Susan Treves ◽  
Clara Franzini-Armstrong ◽  
Luca Moccagatta ◽  
Christophe Arnoult ◽  
Cristiano Grasso ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Intracellular Calcium ◽  
Calcium Binding ◽  
Calcium Release ◽  
Transient Receptor Potential ◽  
Receptor Activation ◽  
Calcium Entry ◽  
Calcium Stores ◽  
Store Depletion ◽  
Insp3 Receptors

In many cell types agonist-receptor activation leads to a rapid and transient release of Ca2+ from intracellular stores via activation of inositol 1,4,5 trisphosphate (InsP3) receptors (InsP3Rs). Stimulated cells activate store- or receptor-operated calcium channels localized in the plasma membrane, allowing entry of extracellular calcium into the cytoplasm, and thus replenishment of intracellular calcium stores. Calcium entry must be finely regulated in order to prevent an excessive intracellular calcium increase. Junctate, an integral calcium binding protein of endo(sarco)plasmic reticulum membrane, (a) induces and/or stabilizes peripheral couplings between the ER and the plasma membrane, and (b) forms a supramolecular complex with the InsP3R and the canonical transient receptor potential protein (TRPC) 3 calcium entry channel. The full-length protein modulates both agonist-induced and store depletion–induced calcium entry, whereas its NH2 terminus affects receptor-activated calcium entry. RNA interference to deplete cells of endogenous junctate, knocked down both agonist-activated calcium release from intracellular stores and calcium entry via TRPC3. These results demonstrate that junctate is a new protein involved in calcium homeostasis in eukaryotic cells.

Pharmacological investigation of signaling mechanisms contributing to phasic and tonic components of the contractile response of rat arteries to noradrenaline

1995 ◽  
Vol 73 (5) ◽  
pp. 594-601 ◽  
Author(s):  
Lynn P. Weber ◽  
Wing L. Chow ◽  
Janice Moshenko ◽  
Slavica Belsher ◽  
Kathleen M. MacLeod
Keyword(s):  
Intracellular Calcium ◽  
Mesenteric Artery ◽  
Calcium Release ◽  
Contractile Response ◽  
Calcium Influx ◽  
Calcium Stores ◽  
Maximal Concentration ◽  
Tonic Component ◽  
Signaling Mechanisms ◽  
Intracellular Calcium Release

The mechanisms contributing to the contractile responses to two different concentrations of noradrenaline (NA) in rat aorta and mesenteric artery were compared using nifedipine, which inhibits calcium influx through dihydropyridine-sensitive channels, ryanodine, which depletes intracellular calcium stores, and calphostin C, which inhibits protein kinase C (PKC). Both submaximal and maximal concentrations of NA induced a biphasic response in aorta and mesenteric artery, with an early fast phase and a later sustained tonic component. Calcium release from intracellular stores contributed to the phasic component of contraction to both concentrations of NA in aorta, although to a greater extent to the submaximal concentration. In aorta, inhibiting both intracellular calcium release and calcium influx through dihydropyridine-sensitive channels simultaneously or inhibiting PKC activity alone significantly reduced the tonic response to a maximal concentration of NA. However, the tonic response to a submaximal concentration of NA in aorta was significantly inhibited only when intracellular calcium stores were depleted with ryanodine. In mesenteric artery, the phasic response to a maximal concentration of NA was significantly depressed only when both calcium influx and intracellular calcium release were inhibited simultaneously. However, the phasic response to a submaximal concentration of NA was significantly inhibited by blocking calcium influx alone, but not by blocking intracellular calcium release alone. The tonic component of the contractile response to both concentrations of NA in mesenteric artery appeared to be mediated in part by calcium from both intracellular and extracellular sources. However, the submaximal concentration relied on calcium influx to a greater extent than the maximal concentration, while PKC contributed to a greater extent to the response to the maximal concentration of NA in this artery. These results indicate that the relative contributions of the signaling mechanisms activated by NA differ between maximal and submaximal concentrations of the agonist as well as between different arteries.Key words: noradrenaline, vasoconstriction, ryanodine, nifedipine, calphostin C.

Simultaneous exposure to ATP and phenylephrine induces a sustained elevation in the intracellular calcium concentration in supraoptic neurons

2006 ◽  
Vol 291 (1) ◽  
pp. R37-R45 ◽  
Author(s):  
Zhilin Song ◽  
Sukumar Vijayaraghavan ◽  
Celia D. Sladek
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Calcium Influx ◽  
Intracellular Calcium Concentration ◽  
Calcium Stores ◽  
Simultaneous Exposure ◽  
Peak Response ◽  
Synergistic Response ◽  
Supraoptic Neurons

Vasopressin (VP) release from the hypothalamo-neurohypophyseal system (HNS) is stimulated by ATP activation of P2X purinergic receptors and by activation of α1-adrenergic receptors by phenylephrine (PE). These responses are potentiated by simultaneous exposure to ATP+PE. Potentiation was blocked by depleting intracellular calcium stores with thapsigargin. To test the hypothesis that the synergistic response to ATP+PE reflects alterations in the intracellular calcium concentration ([Ca2+]i), [Ca2+]i was monitored in supraoptic neurons in HNS explants loaded with fura 2-AM. Both ATP and PE induced rapid, but transient, elevations in [Ca2+]i. In 0.3 mM Ca2+, the peak response to ATP was greater than to PE but did not differ from the peak response to ATP+PE. A sustained elevation in [Ca2+]i was induced by ATP+PE, that was greater than ATP or PE alone. In 2 mM Ca2+, the peak response to ATP+PE was significantly greater than to either ATP or PE alone, and the sustained response to ATP+PE was greater than to either agent alone. Responses were comparable in the presence of TTX. The sustained elevation in [Ca2+]i was also observed when ATP+PE was removed after 1 min, but it was eliminated by either thapsigargin or removing external calcium, indicating that both calcium influx and calcium release from internal stores are required. Some cells were vasopressinergic based on a VP-induced increase in [Ca2+]i. These observations support the hypothesis that simultaneous exposure to ATP+PE induces a different pattern of [Ca2+]i than either agent alone that may initiate events leading to synergistic stimulation of VP release.

scholarly journals New Insights on the Role of TRP Channels in Calcium Signalling and Immunomodulation: Review of Pathways and Implications for Clinical Practice

2021 ◽  
Author(s):  
Saied Froghi ◽  
Charlotte R. Grant ◽  
Radhika Tandon ◽  
Alberto Quaglia ◽  
Brian Davidson ◽  
...  
Keyword(s):  
Immune System ◽  
Calcium Release ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Calcium Influx ◽  
Calcium Signalling ◽  
Chronic Fatigue ◽  
Diverse Range ◽  
Immune System Activation

AbstractCalcium is the most abundant mineral in the human body and is central to many physiological processes, including immune system activation and maintenance. Studies continue to reveal the intricacies of calcium signalling within the immune system. Perhaps the most well-understood mechanism of calcium influx into cells is store-operated calcium entry (SOCE), which occurs via calcium release-activated channels (CRACs). SOCE is central to the activation of immune system cells; however, more recent studies have demonstrated the crucial role of other calcium channels, including transient receptor potential (TRP) channels. In this review, we describe the expression and function of TRP channels within the immune system and outline associations with murine models of disease and human conditions. Therefore, highlighting the importance of TRP channels in disease and reviewing potential. The TRP channel family is significant, and its members have a continually growing number of cellular processes. Within the immune system, TRP channels are involved in a diverse range of functions including T and B cell receptor signalling and activation, antigen presentation by dendritic cells, neutrophil and macrophage bactericidal activity, and mast cell degranulation. Not surprisingly, these channels have been linked to many pathological conditions such as inflammatory bowel disease, chronic fatigue syndrome and myalgic encephalomyelitis, atherosclerosis, hypertension and atopy.

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