scholarly journals Hypotonicity-induced cell swelling activates TRPA1

2017 ◽  
Vol 68 (4) ◽  
pp. 431-440 ◽  
Author(s):  
Fumitaka Fujita ◽  
Kunitoshi Uchida ◽  
Yasunori Takayama ◽  
Yoshiro Suzuki ◽  
Masayuki Takaishi ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Single Channel ◽  
Cell Swelling ◽  
Imaging Method ◽  
Channel Activation ◽  
Patch Pipette ◽  
Physical Stimuli ◽  
A Cell ◽  
Single Channel Currents ◽  
Channel Currents

Abstract Hypotonic solutions can cause painful sensations in nasal and ocular mucosa through molecular mechanisms that are not entirely understood. We clarified the ability of human TRPA1 (hTRPA1) to respond to physical stimulus, and evaluated the response of hTRPA1 to cell swelling under hypotonic conditions. Using a Ca2+-imaging method, we found that modulation of AITC-induced hTRPA1 activity occurred under hypotonic conditions. Moreover, cell swelling in hypotonic conditions evoked single-channel activation of hTRPA1 in a cell-attached mode when the patch pipette was attached after cell swelling under hypotonic conditions, but not before swelling. Single-channel currents activated by cell swelling were also inhibited by a known hTRPA1 blocker. Since pre-application of thapsigargin or pretreatment with the calcium chelator BAPTA did not affect the single-channel activation induced by cell swelling, changes in intracellular calcium concentrations are likely not related to hTRPA1 activation induced by physical stimuli.

Single potassium channels blocked by lidocaine and quinidine in isolated turtle colon epithelial cells

1986 ◽  
Vol 251 (1) ◽  
pp. C85-C89 ◽  
Author(s):  
N. W. Richards ◽  
D. C. Dawson
Keyword(s):  
Epithelial Cells ◽  
Single Channel ◽  
Reversal Potential ◽  
Cell Swelling ◽  
K Channel ◽  
Patch Clamp Technique ◽  
Colon Cells ◽  
High K ◽  
A Cell ◽  
Single Channel Currents

The patch-clamp technique for recording single-channel currents across cell membranes was applied to single turtle colon epithelial cells isolated with hyaluronidase. With electrodes fabricated from Corning #7052 glass, high-resistance seals were consistently formed to these cells. In on-cell patches with low K (2.5 mM) in the pipette and high K (114.5 mM) in the bath, outward K currents were recorded that had a slope conductance of 17 pS and a reversal potential greater than -70 mV. Currents through this K channel were blocked by lidocaine, quinidine, and barium. These agents also block a cell swelling-induced K conductance identified by macroscopic current measurements in the basolateral membranes of the intact colonic epithelium, suggesting that the 17 pS K channel identified by single-channel recording in isolated turtle colon cells may be responsible for this macroscopically defined K conductance.

scholarly journals Ion channels activated by light in Limulus ventral photoreceptors.

1986 ◽  
Vol 87 (1) ◽  
pp. 73-89 ◽  
Author(s):  
J Bacigalupo ◽  
K Chinn ◽  
J E Lisman
Keyword(s):  
Light Adaptation ◽  
Voltage Dependence ◽  
Single Channel ◽  
Patch Clamp Technique ◽  
Channel Activation ◽  
Voltage Range ◽  
Secondary Result ◽  
Channel Open Time ◽  
Single Channel Currents ◽  
Channel Currents

The light-activated conductance of Limulus ventral photoreceptors was studied using the patch-clamp technique. Channels (40 pS) were observed whose probability of opening was greatly increased by light. In some cells the latency of channel activation was nearly the same as that of the macroscopic response, while in other cells the channel latency was much greater. Like the macroscopic conductance, channel activity was reduced by light adaptation but enhanced by the intracellular injection of the calcium chelator EGTA. The latter observation indicates that channel activation was not a secondary result of the light-induced rise in intracellular calcium. A two-microelectrode voltage-clamp method was used to measure the voltage dependence of the light-activated macroscopic conductance. It was found that this conductance is constant over a wide voltage range more negative than zero, but it increases markedly at positive voltages. The single channel currents measured over this same voltage range show that the single channel conductance is independent of voltage, but that channel gating properties are dependent on voltage. Both the mean channel open time and the opening rate increase at positive voltages. These properties change in a manner consistent with the voltage dependence of the macroscopic conductance. The broad range of similarities between the macroscopic and single channel currents supports the conclusion that the 40-pS channel that we have observed is the principal channel underlying the response to light in these photoreceptors.

A Calcium-Activated Nonspecific Cation Channel from Olfactory Receptor Neurones of the Silkmoth Antheraea Polyphemus

1991 ◽  
Vol 161 (1) ◽  
pp. 455-468
Author(s):  
F. ZUFALL ◽  
H. HATT ◽  
T. A. KEIL
Keyword(s):  
Olfactory Receptor ◽  
Single Channel ◽  
Membrane Vesicles ◽  
Cation Channel ◽  
Voltage Response ◽  
Antheraea Polyphemus ◽  
Cell Excitability ◽  
Olfactory Receptor Neurones ◽  
Single Channel Currents ◽  
Channel Currents

Single-channel patch-clamp techniques were used to identify and characterize a Ca2+-activated nonspecific cation channel (CAN channel) on insect olfactory receptor neurones (ORNs) from antennae of male Antheraea polyphemus. The CAN channel was found both in acutely isolated ORNs from developing pupae and in membrane vesicles from mature ORNs that presumably originated from inner dendritic segments. Amplitude histograms of the CAN single-channel currents presented well-defined peaks corresponding to at least four channel substates each having a conductance of about 16 pS. Simultaneous gating of the substates was achieved by intracellular Ca2+ with an EC50 value of about 80 nmoll−1. Activity of the CAN channel could be blocked by application of amiloride (IC50 <100nmoll−1). Moreover, in the presence of 1μmoll−1 Ca2+, opening of the CAN channel was totally suppressed by 10 μmoll−1 cyclic GMP, whereas ATP (1 mmol l−1) was without effect. We suggest that the CAN channel plays a specific role in modulation of cell excitability and in shaping the voltage response of ORNs.

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