Effects of internal divalent cations on the gating of rat brain Na+ channels reconstituted in planar lipid bilayers

1991 ◽  
Vol 419 (6) ◽  
pp. 559-565 ◽  
Author(s):  
Samuel Cukierman ◽  
Bruce K. Krueger
Keyword(s):  
Rat Brain ◽  
Lipid Bilayers ◽  
Divalent Cations ◽  
Planar Lipid Bilayers ◽  
Na Channels

scholarly journals Saturation behavior of single, amiloride-sensitive Na+ channels in planar lipid bilayers

1984 ◽  
Vol 46 (6) ◽  
pp. 831-835 ◽  
Author(s):  
L. Olans ◽  
S. Sariban-Sohraby ◽  
D.J. Benos
Keyword(s):  
Lipid Bilayers ◽  
Planar Lipid Bilayers ◽  
Na Channels

Opening of large-conductance calcium-activated potassium channels by the substituted benzimidazolone NS004

1994 ◽  
Vol 71 (5) ◽  
pp. 1873-1882 ◽  
Author(s):  
M. C. McKay ◽  
S. I. Dworetzky ◽  
N. A. Meanwell ◽  
S. P. Olesen ◽  
P. H. Reinhart ◽  
...  
Keyword(s):  
Rat Brain ◽  
Lipid Bilayers ◽  
Single Channel ◽  
Outward Current ◽  
Calcium Sensitivity ◽  
Bk Channels ◽  
Gh3 Cells ◽  
Xenopus Laevis Oocytes ◽  
Planar Lipid Bilayers ◽  
Whole Cell

1. We used electrophysiological techniques to examine the effects of 5-trifluoromethyl-1-(5-chloro-2-hydroxyphenyl)-1,3-dihydro-2H-benzimidaz ole- 2-one (NS004) on large-conductance calcium-activated potassium (BK) channels. 2. We used recordings from excised membrane patches (cell-attached and inside-out single-channel configurations) and whole-cell patch-clamp recordings to examine the effects of NS004 on single BK channels and whole-cell outward currents, respectively, in rat GH3 clonal pituitary tumor cells. We also tested NS004 on voltage-clamped BK channels isolated from rat brain plasma membrane preparations and reconstituted into planar lipid bilayers. Finally, we used two-electrode voltage-clamp techniques to study the effects of NS004 on currents expressed in Xenopus laevis oocytes by the recently described Slo BK clone from Drosophila. 3. In GH3 cells and in Xenopus oocytes expressing the Slo gene product NS004 produced an increase in an iberiotoxin- or tetraethylammonium-sensitive whole-cell outward current, respectively. NS004 produced a significant increase in the activity of single GH3 cell BK channels and rat brain BK channels reconstituted into planar lipid bilayers. In both systems this was characterized by an increase in channel mean open time, a decrease in interburst interval, and an apparent increase in channel voltage/calcium sensitivity. 4. These data indicate that NS004 could be useful for investigating the biophysical and molecular properties of BK channels and for determining the functional consequences of the opening of BK channels.

scholarly journals Regulation of Epithelial Na+Channels by Actin in Planar Lipid Bilayers and in theXenopusOocyte Expression System

1999 ◽  
Vol 274 (53) ◽  
pp. 37845-37854 ◽  
Author(s):  
Biljana Jovov ◽  
Albert Tousson ◽  
Hong-Long Ji ◽  
Deborah Keeton ◽  
Vadim Shlyonsky ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Expression System ◽  
Planar Lipid Bilayers ◽  
Na Channels ◽  
Epithelial Na Channels

scholarly journals Batrachotoxin-activated Na+ channels in planar lipid bilayers. Competition of tetrodotoxin block by Na+.

1984 ◽  
Vol 84 (5) ◽  
pp. 665-686 ◽  
Author(s):  
E Moczydlowski ◽  
S S Garber ◽  
C Miller
Keyword(s):  
Lipid Bilayers ◽  
Membrane Vesicles ◽  
Receptor Site ◽  
Single Channels ◽  
Planar Lipid Bilayers ◽  
Na Channels ◽  
Plasma Membrane Vesicles ◽  
Voltage Range ◽  
Conduction Pathway ◽  
Almost All

Single Na+ channels from rat skeletal muscle plasma membrane vesicles were inserted into planar lipid bilayers formed from neutral phospholipids and were observed in the presence of batrachotoxin. The batrachotoxin-modified channel activates in the voltage range -120 to -80 mV and remains open almost all the time at voltages positive to -60 mV. Low levels of tetrodotoxin (TTX) induce slow fluctuations of channel current, which represent the binding and dissociation of single TTX molecules to single channels. The rates of association and dissociation of TTX are both voltage dependent, and the association rate is competitively inhibited by Na+. This inhibition is observed only when Na+ is increased on the TTX binding side of the channel. The results suggest that the TTX receptor site is located at the channel's outer mouth, and that the Na+ competition site is not located deeply within the channel's conduction pathway.

scholarly journals Reconstitution of highly purified saxitoxin-sensitive Na+-channels into planar lipid bilayers.

1984 ◽  
Vol 3 (3) ◽  
pp. 509-515 ◽  
Author(s):  
W. Hanke ◽  
G. Boheim ◽  
J. Barhanin ◽  
D. Pauron ◽  
M. Lazdunski
Keyword(s):  
Lipid Bilayers ◽  
Planar Lipid Bilayers ◽  
Na Channels

scholarly journals Cocaine-induced closures of single batrachotoxin-activated Na+ channels in planar lipid bilayers.

1988 ◽  
Vol 92 (6) ◽  
pp. 747-765 ◽  
Author(s):  
G K Wang
Keyword(s):  
Binding Site ◽  
Binding Affinity ◽  
Lipid Bilayers ◽  
Local Anesthetics ◽  
Direct Interaction ◽  
Na Channel ◽  
Planar Lipid Bilayers ◽  
Na Channels ◽  
Single Class ◽  
Na Ions

Batrachotoxin (BTX)-activated Na+ channels from rabbit skeletal muscle were incorporated into planar lipid bilayers. These channels appear to open most of the time at voltages greater than -60 mV. Local anesthetics, including QX-314, bupivacaine, and cocaine when applied internally, induce different durations of channel closures and can be characterized as "fast" (mean closed duration less than 10 ms at +50 mV), "intermediate" (approximately 80 ms), and "slow" (approximately 400 ms) blockers, respectively. The action of these local anesthetics on the Na+ channel is voltage dependent; larger depolarizations give rise to stronger binding interactions. Both the dose-response curve and the kinetics of the cocaine-induced closures indicate that there is a single class of cocaine-binding site. QX-314, though a quaternary-amine local anesthetic, apparently competes with the same binding site. External cocaine or bupivacaine application is almost as effective as internal application, whereas external QX-314 is ineffective. Interestingly, external Na+ ions reduce the cocaine binding affinity drastically, whereas internal Na+ ions have little effect. Both the cocaine association and dissociation rate constants are altered when external Na+ ion concentrations are raised. We conclude that (a) one cocaine molecule closes one BTX-activated Na+ channel in an all-or-none manner, (b) the binding affinity of cocaine is voltage sensitive, (c) this cocaine binding site can be reached by a hydrophilic pathway through internal surface and by a hydrophobic pathway through bilayer membrane, and (d) that this binding site interacts indirectly with the Na+ ions. A direct interaction between the receptor and Na+ ions seems minimal.

scholarly journals Carboxyl methylation activates purified renal amiloride-sensitive Na+ channels in planar lipid bilayers.

1994 ◽  
Vol 269 (35) ◽  
pp. 22193-22197 ◽  
Author(s):  
I.I. Ismailov ◽  
J.H. McDuffie ◽  
S. Sariban-Sohraby ◽  
J.P. Johnson ◽  
D.J. Benos
Keyword(s):  
Lipid Bilayers ◽  
Planar Lipid Bilayers ◽  
Na Channels ◽  
Carboxyl Methylation

Reconstitution of immunopurified alveolar type II cell Na+ channel protein into planar lipid bilayers

1995 ◽  
Vol 268 (5) ◽  
pp. C1148-C1156 ◽  
Author(s):  
O. Senyk ◽  
I. Ismailov ◽  
A. L. Bradford ◽  
R. R. Baker ◽  
S. Matalon ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Single Channel ◽  
Na Channel ◽  
Alveolar Type ◽  
Planar Lipid Bilayers ◽  
Type Ii ◽  
Na Channels ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Channel Protein

Low-amiloride-affinity (L-type) Na+ channels have been functionally and immunologically localized to alveolar type II (ATII) cells. Purified rabbit ATII epithelial cells were isolated by elastase digestion and solubilized with 3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate. The solubilized proteins were purified by ion-exchange chromatography, followed by immunoaffinity purification over a column to which rabbit polyclonal antibodies raised against purified bovine renal Na+ channel protein were bound. The proteins eluted from the immunoaffinity column were assayed for specific binding of [3H]Br-benzamil and reconstituted into planar lipid bilayers. Sequential purification steps gave a final enrichment in specific [3H]Br-benzamil binding of > 2,000 compared with the homogenate. Single-channel currents of 25 pS were recorded from the immunopurified rabbit ATII cell protein. Addition of the catalytic subunit of protein kinase A (PKA) plus ATP to the presumed cytoplasmic side of the bilayer resulted in a significant increase in the single-channel open probability (Po), from 0.40 +/- 0.14 to 0.8 +/- 0.12, without altering single-channel conductance. The addition of amiloride or ethylisopropyl amiloride (EIPA) to the side opposite that in which PKA acts reduced Po with no change in single-channel conductance. Rabbit ATII Na+ channels in bilayers had an inhibitory constant for amiloride of 8 microM and 1 microM for EIPA. These data confirm the presence of L-type Na+ channels in adult mammalian ATII cells.

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