Sodium-activated potassium current in sensory neurons: a comparison of cell-attached and cell-free single-channel activities

1992 ◽  
Vol 422 (3) ◽  
pp. 287-294 ◽  
Author(s):  
Claudia Haimann ◽  
Jacopo Magistretti ◽  
Bernadette Pozzi
Keyword(s):  
Sensory Neurons ◽  
Potassium Current ◽  
Single Channel

Angiotensin II increases excitability and inhibits a transient potassium current in vagal primary sensory neurons

Neuropeptides ◽  
2009 ◽  
Vol 43 (3) ◽  
pp. 193-199 ◽  
Author(s):  
Thaís Helena Moreira ◽  
Jader Santos Cruz ◽  
Daniel Weinreich
Keyword(s):  
Angiotensin Ii ◽  
Sensory Neurons ◽  
Potassium Current ◽  
Primary Sensory Neurons

scholarly journals Calmodulin Contributes to Gating Control in Olfactory Calcium-activated Chloride Channels

2006 ◽  
Vol 127 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Hiroshi Kaneko ◽  
Frank Möhrlen ◽  
Stephan Frings
Keyword(s):  
Sensory Neurons ◽  
Signal Amplification ◽  
Single Channel ◽  
Feedback Inhibition ◽  
Ion Selectivity ◽  
Sensory Information ◽  
Activation Mechanism ◽  
Ca Channels ◽  
Cl Channels ◽  
Ca Sensitivity

In sensory neurons of the peripheral nervous system, receptor potentials can be amplified by depolarizing Cl currents. In mammalian olfactory sensory neurons (OSNs), this anion-based signal amplification results from the sequential activation of two distinct types of transduction channels: cAMP-gated Ca channels and Ca-activated Cl channels. The Cl current increases the initial receptor current about 10-fold and leads to the excitation of the neuron. Here we examine the activation mechanism of the Ca-dependent Cl channel. We focus on calmodulin, which is known to mediate Ca effects on various ion channels. We show that the cell line Odora, which is derived from OSN precursor cells in the rat olfactory epithelium, expresses Ca-activated Cl channels. Single-channel conductance, ion selectivity, voltage dependence, sensitivity to niflumic acid, and Ca sensitivity match between Odora channels and OSN channels. Transfection of Odora cells with CaM mutants reduces the Ca sensitivity of the Cl channels. This result points to the participation of calmodulin in the gating process of Ca-ativated Cl channels, and helps to understand how signal amplification works in the olfactory sensory cilia. Calmodulin was previously shown to mediate feedback inhibition of cAMP-synthesis and of the cAMP-gated Ca channels in OSNs. Our results suggest that calmodulin may also be instrumental in the generation of the excitatory Cl current. It appears to play a pivotal role in the peripheral signal processing of olfactory sensory information. Moreover, recent results from other peripheral neurons, as well as from smooth muscle cells, indicate that the calmodulin-controlled, anion-based signal amplification operates in various cell types where it converts Ca signals into membrane depolarization.

Prostaglandin e2 inhibits the potassium current in sensory neurons from hyperalgesic kv1.1 knockout mice

Neuroscience ◽  
2003 ◽  
Vol 119 (1) ◽  
pp. 65-72 ◽  
Author(s):  
X. Jiang ◽  
Y.H. Zhang ◽  
J.D. Clark ◽  
B.L. Tempel ◽  
G.D. Nicol
Keyword(s):  
Prostaglandin E2 ◽  
Sensory Neurons ◽  
Knockout Mice ◽  
Potassium Current

scholarly journals Colitis decreases mechanosensitive K2P channel expression and function in mouse colon sensory neurons

2011 ◽  
Vol 301 (1) ◽  
pp. G165-G174 ◽  
Author(s):  
Jun-Ho La ◽  
G. F. Gebhart
Keyword(s):  
Sensory Neurons ◽  
Single Channel ◽  
Outward Current ◽  
Trinitrobenzene Sulfonic Acid ◽  
Drg Neurons ◽  
Colon Wall ◽  
Membrane Stretch ◽  
Colon Inflammation ◽  
Mouse Colon ◽  
Neuronal Membranes

TREK-1, TREK-2 and TRAAK are mechanosensitive two-pore domain K+ (K2P) channels thought to be involved in the attenuation of mechanotransduction. Because colon inflammation is associated with colon mechanohypersensitivity, we hypothesized that the role of these channels in colon sensory (dorsal root ganglion, DRG) neurons would be reduced by colon inflammation. Accordingly, we studied the functional expression of mechanosensitive K2P channels in colon sensory neurons in both thoracolumbar (TL) and lumbosacral (LS) DRG that represent the splanchnic and pelvic nerve innervations of the colon, respectively. In colon DRG neurons identified by retrograde tracer previously injected into the colon wall, 62% of TL neurons and 83% of LS neurons expressed at least one of three K2P channel mRNAs; the proportion of neurons expressing the TREK-1 gene was greater in LS than in TL DRG. In electrophysiological studies, single-channel activities of TREK-1a, TREK-1b, TREK-2, and TRAAK-like channels were detected in cultured colon DRG neuronal membranes. After trinitrobenzene sulfonic acid-induced colon inflammation, we observed significant decreases in the amount of TREK-1 mRNA, in the response of TREK-2-like channels to membrane stretch, and in the whole cell outward current during osmotic stretch in LS colon DRG neurons. These findings document that the majority of DRG neurons innervating the mouse colon express mechanosensitive K2P channels and suggest that a decrease in their expression and activities contributes to the increased colon mechanosensitivity that develops in inflammatory bowel conditions.

scholarly journals TRESK and TREK-2 two-pore-domain potassium channel subunits form functional heterodimers in primary somatosensory neurons

2020 ◽  
Vol 295 (35) ◽  
pp. 12408-12425 ◽  
Author(s):  
Miklós Lengyel ◽  
Gábor Czirják ◽  
David A. Jacobson ◽  
Péter Enyedi
Keyword(s):  
Sensory Neurons ◽  
Single Channel ◽  
Potassium Conductance ◽  
Dominant Negative ◽  
Resting Membrane Potential ◽  
Pharmacological Properties ◽  
Primary Sensory Neurons ◽  
Somatosensory Neurons ◽  
Covalently Linked ◽  
Pore Domain

Two-pore-domain potassium channels (K2P) are the major determinants of the background potassium conductance. They play a crucial role in setting the resting membrane potential and regulating cellular excitability. These channels form homodimers; however, a few examples of heterodimerization have also been reported. The K2P channel subunits TRESK and TREK-2 provide the predominant background potassium current in the primary sensory neurons of the dorsal root and trigeminal ganglia. A recent study has shown that a TRESK mutation causes migraine because it leads to the formation of a dominant negative truncated TRESK fragment. Surprisingly, this fragment can also interact with TREK-2. In this study, we determined the biophysical and pharmacological properties of the TRESK/TREK-2 heterodimer using a covalently linked TRESK/TREK-2 construct to ensure the assembly of the different subunits. The tandem channel has an intermediate single-channel conductance compared with the TRESK and TREK-2 homodimers. Similar conductance values were recorded when TRESK and TREK-2 were coexpressed, demonstrating that the two subunits can spontaneously form functional heterodimers. The TRESK component confers calcineurin-dependent regulation to the heterodimer and gives rise to a pharmacological profile similar to the TRESK homodimer, whereas the presence of the TREK-2 subunit renders the channel sensitive to the selective TREK-2 activator T2A3. In trigeminal primary sensory neurons, we detected single-channel activity with biophysical and pharmacological properties similar to the TRESK/TREK-2 tandem, indicating that WT TRESK and TREK-2 subunits coassemble to form functional heterodimeric channels also in native cells.

scholarly journals Single-channel basis for the slow activation of the repolarizing cardiac potassium current,IKs

2013 ◽  
Vol 110 (11) ◽  
pp. E996-E1005 ◽  
Author(s):  
Daniel Werry ◽  
Jodene Eldstrom ◽  
Zhuren Wang ◽  
David Fedida
Keyword(s):  
Potassium Current ◽  
Single Channel ◽  
Cardiac Potassium Current

scholarly journals Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons.

1990 ◽  
Vol 95 (5) ◽  
pp. 961-979 ◽  
Author(s):  
C Haimann ◽  
L Bernheim ◽  
D Bertrand ◽  
C R Bader
Keyword(s):  
Voltage Clamp ◽  
Trigeminal Ganglion ◽  
Potassium Current ◽  
Single Channel ◽  
Sodium Concentration ◽  
Intracellular Sodium ◽  
Single Channel Recordings ◽  
Trigeminal Ganglion Neurons ◽  
Ganglion Neurons ◽  
The Relationship

Whole-cell voltage clamp and single-channel recordings were performed on cultured trigeminal ganglion neurons from quail embryos in order to study a sodium-activated potassium current (KNa). When KNa was activated by a step depolarization in voltage clamp, there was a proportionality between KNa and INa at all voltages between the threshold of INa and ENa. Single-channel recordings indicated that KNa could be activated already by 12 mM intracellular sodium and was almost fully activated at 50 mM sodium. 100 mM lithium, 100 mM choline, or 5 microM calcium did not activate KNa. The relationship between the probability for the channel to be open (Po) vs. the sodium concentration and the relationship of KNa open time-distributions vs. the sodium concentration suggest that two to three sodium ions bind cooperatively before KNa channels open. KNa channels were sensitive to depolarization; at 12 mM sodium, a 42-mV depolarization caused an e-fold increase in Po. Under physiological conditions, the conductance of the KNa channel was 50 pS. This conductance increased to 174 pS when the intra- and extracellular potassium concentrations were 75 and 150 mM, respectively.

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