Changes in Cytoplasmic Calcium Induced by Purinergic P2x Receptor Activation in Vascular Smooth Muscle Cells and Sensory Neurons

Benham, Christopher D.; Bouvier, Muriel; Evans, Marcus

doi:10.1007/978-1-4684-6003-2_19

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…For example, in smooth muscle cells, reversal potential measurements allowed an estimation of P Ca /P Na = 3 for P2XR-mediated currents, which is in agreement with the highly Ca 2+ permeable P2X1R being a predominant subtype in this tissue (Benham et al, 1991). Reversal potential experiments conducted in ATP-sensitive neurons have yielded Ca 2+ permeability values of P Ca /P Cs = ~1.5 for nodose ganglion neurons (Virginio et al, 1998) and P Ca /P Cs = ~2 for retinal ganglion neurons (Taschenberger et al, 1999), both cell types of which likely express homo- and heteromeric P2X2R and P2X3R.…”

Section: Ion Selection and Permeationsupporting

confidence: 65%

Principles and properties of ion flow in P2X receptors

Samways

Egan

2014

Front. Cell. Neurosci.

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P2X receptors are a family of trimeric ion channels that are gated by extracellular adenosine 5′-triphosphate (ATP). These receptors have long been a subject of intense research interest by virtue of their vital role in mediating the rapid and direct effects of extracellular ATP on membrane potential and cytosolic Ca2+ concentration, which in turn underpin the ability of ATP to regulate a diverse range of clinically significant physiological functions, including those associated with the cardiovascular, sensory, and immune systems. An important aspect of an ion channel's function is, of course, the means by which it transports ions across the biological membrane. A concerted effort by investigators over the last two decades has culminated in significant advances in our understanding of how P2X receptors conduct the inward flux of Na+ and Ca2+ in response to binding by ATP. However, this work has relied heavily on results from current recordings of P2X receptors altered by site-directed mutagenesis. In the absence of a 3-dimensional channel structure, this prior work provided only a vague and indirect appreciation of the relationship between structure, ion selectivity and flux. The recent publication of the crystal structures for both the closed and open channel conformations of the zebrafish P2X4 receptor has thus proved a significant boon, and has provided an important opportunity to overview the amassed functional data in the context of a working 3-dimensional model of a P2X receptor. In this paper, we will attempt to reconcile the existing functional data regarding ion permeation through P2X receptors with the available crystal structure data, highlighting areas of concordance and discordance as appropriate.

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Section: Ion Selection and Permeationsupporting

confidence: 65%

Principles and properties of ion flow in P2X receptors

Samways

Egan

2014

Front. Cell. Neurosci.

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“…These results are essentially the same as those reported for recombinant P2X 1 and P2X 2 receptors and indicate that P2X receptors share a common ionic selectivity filter for monovalent cations. However, there are variations in calcium permeability and the ability to form dilating pores between both recombinant and native P2X receptor that can be used to distinguish receptor subtypes [Benham et al, 1991;Evans et al, 1996;Rassendren et al, 1997;Virginio et al, 1998;Khakh et al, 1999]. The high relative calcium permeability of artery P2X receptors (P Ca /P Na ∼3.5) in the present study is the same as that in previous reports in rabbit ear artery smooth muscle [Benham and Tsien, 1987] and for recombinant P2X 1 receptors .…”

Section: Discussionsupporting

confidence: 84%

Permeability and single‐channel properties of mesenteric, basilar, and septal (coronary) artery smooth‐muscle P2X receptors

Lewis

Davies

Evans

2001

Drug Development Research

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P2X 1 receptors for ATP are expressed in vascular smooth muscle and are thought to underlie the native artery smooth muscle rapidly desensitising α,β-methylene ATP (α,β-meATP) sensitive P2X receptor phenotype. We have characterised the ionic permeability and single-channel conductance from rat mesenteric, basilar, and septal (coronary) arteries. The relative permeabilities (P X /P Na ) to methylamine, dimethylamine, and Tris were essentially the same for all three arteries and give an estimate of the minimum diameter of the ionic pore as 0.8 nm. The P2X receptor channels in arteries had a high calcium permeability (P Ca 2+ /P Na ∼3.5). In outside-out patches, α,β-meATP evoked transient currents with a singlechannel conductance of ∼12 pS (in physiological solution with 2.5 mM Ca 2+ and 1 mM Mg 2+). The singlechannel conductance was increased to ∼17 pS with a 0.1 mM Ca 2+ -and nominally Mg 2+ -free physiological solution. These properties for artery P2X receptors are essentially the same as for recombinant P2X 1 receptors and confirm that homomeric P2X 1 receptors underlie the native P2X receptor current phenotype in these arteries. Drug Dev. Res. 52:164-169, 2001.

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“…The permeation of Ca 2+ is of particular interest because of its role as a second messenger (Benham, 1990(Benham, , 1992. The Ca 2+ permeability of ATPgated channels has been measured utilizing reversal potentials of whole cell currents, single channel recordings, and analysis of the ATP-induced rise in intracellular Ca 2+ (Benham, Bouvier & Evans, 1991;Rogers & Dani, 1995;Evans et al, 1996;Virginio et al, 1998). However, since intracellular Ca 2+ can modify the gating of many other channels, whole cell reversal potential measurements of Ca 2+ permeability may not be trustworthy.…”

Section: Introductionmentioning

confidence: 99%

Ion Permeation and Block of P2X 2 Purinoceptors: Single Channel Recordings

Ding

Sachs

1999

Journal of Membrane Biology

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P2X(2) purinoceptors are cation-selective channels activated by ATP and its analogues. Using single channel measurements we studied the channel's selectivity for the alkali metal ions and organic monovalent cations NMDG(+), Tris(+), TMA(+), and TEA(+). The selectivity sequence for currents carried by alkali metal ions is: K(+) > Rb(+) > Cs(+) > Na(+) > Li(+), which is Eisenman sequence IV. This is different from the mobility sequence of the ions in free solution suggesting there is weak interaction between the ions and the channel interior. The relative conductance for alkali ions increases linearly in relation to the Stokes radius. The organic ions NMDG(+), Tris(+), TMA(+) and TEA(+) were virtually impermeant. The divalent ions (Mn(2+), Mg(2+), Ca(2+) and Ba(2+)) induced a fast block visible as a reduction in amplitude of the unitary currents. Using a single-site binding model, the divalent ions exhibited an equilibrium affinity sequence of Mn(2+) > Mg(2+) > Ca(2+) > Ba(2+).

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Changes in Cytoplasmic Calcium Induced by Purinergic P2x Receptor Activation in Vascular Smooth Muscle Cells and Sensory Neurons

Cited by 8 publications

References 22 publications

Principles and properties of ion flow in P2X receptors

Principles and properties of ion flow in P2X receptors

Permeability and single‐channel properties of mesenteric, basilar, and septal (coronary) artery smooth‐muscle P2X receptors

Ion Permeation and Block of P2X 2 Purinoceptors: Single Channel Recordings

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