Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Unilateral exposure of Shaker B potassium channels to hyperosmolar solutions.
Starkus JG
,
Schlief T
,
Rayner MD
,
Heinemann SH
.
???displayArticle.abstract???
This study tests the hypothesis that ion channels will be affected differently by external (extracellular) versus internal (cytoplasmic) exposure to hyperosmolar media. We looked first for effects on inactivation kinetics in wild-type Shaker B potassium channels. Although external hyperosmolar exposure did not alter the inactivation rate, internal exposure slowed both onset and recovery from fast inactivation. Differential effects on activation kinetics were then characterized by using a noninactivating Shaker B mutant. External hyperosmolar exposure slowed the late rising phase of macroscopic current without affecting the initial delay or early rising phase kinetics. By contrast, internal exposure slowed the initial steps in channel activation with only minimal changes in the later part of the rising phase. Neither external nor internal hyperosmolar exposure affected tail current rates in these noninactivating channels. Additionally, suppression of peak macroscopic current was approximately twofold smaller during external, as compared with internal, hyperosmolar exposure. Single-channel currents, observed under identical experimental conditions, showed a differential suppression equivalent to that seen in macroscopic currents. Apparently, during unilateral hyperosmolar exposure, changes in macroscopic peak current arise primarily from changes in single-channel conductance rather than from changes in equilibrium channel gating. We conclude that unilateral hyperosmolar exposure can provide information concerning the potential structural localization of functional components within ion-channel molecules.
Alicata,
Osmotic and pharmacological effects of formamide on capacity current, gating current, and sodium current in crayfish giant axons.
1989, Pubmed
Alicata,
Osmotic and pharmacological effects of formamide on capacity current, gating current, and sodium current in crayfish giant axons.
1989,
Pubmed
Alicata,
Sodium channel activation mechanisms. Insights from deuterium oxide substitution.
1990,
Pubmed
Andersen,
Ion movement through gramicidin A channels. Studies on the diffusion-controlled association step.
1983,
Pubmed
Armstrong,
Destruction of sodium conductance inactivation in squid axons perfused with pronase.
1973,
Pubmed
COLE,
Potassium ion current in the squid giant axon: dynamic characteristic.
1960,
Pubmed
Colombo,
Protein solvation in allosteric regulation: a water effect on hemoglobin.
1992,
Pubmed
Conti,
Pressure dependence of the sodium currents of squid giant axon.
1982,
Pubmed
Conti,
Pressure dependence of the potassium currents of squid giant axon.
1982,
Pubmed
Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed
Hille,
Local anesthetics: hydrophilic and hydrophobic pathways for the drug-receptor reaction.
1977,
Pubmed
Hoshi,
Biophysical and molecular mechanisms of Shaker potassium channel inactivation.
1990,
Pubmed
,
Xenbase
Iverson,
The role of the divergent amino and carboxyl domains on the inactivation properties of potassium channels derived from the Shaker gene of Drosophila.
1990,
Pubmed
,
Xenbase
Kornblatt,
A nontraditional role for water in the cytochrome c oxidase reaction.
1990,
Pubmed
McCormack,
A characterization of the activating structural rearrangements in voltage-dependent Shaker K+ channels.
1994,
Pubmed
Methfessel,
Patch clamp measurements on Xenopus laevis oocytes: currents through endogenous channels and implanted acetylcholine receptor and sodium channels.
1986,
Pubmed
,
Xenbase
Narahashi,
Tetrodotoxin does not block excitation from inside the nerve membrane.
1966,
Pubmed
Parsegian,
Osmotic stress for the direct measurement of intermolecular forces.
1986,
Pubmed
Rayner,
Voltage-sensitive and solvent-sensitive processes in ion channel gating. Kinetic effects of hyperosmolar media on activation and deactivation of sodium channels.
1992,
Pubmed
Ruppersberg,
Cloned neuronal IK(A) channels reopen during recovery from inactivation.
1991,
Pubmed
Schauf,
Solvent substitution as a probe of channel gating in Myxicola. Effects of D2O on kinetic properties of drugs that occlude channels.
1982,
Pubmed
Schoppa,
The size of gating charge in wild-type and mutant Shaker potassium channels.
1992,
Pubmed
Stimers,
Sodium channel gating currents. Origin of the rising phase.
1987,
Pubmed
Stühmer,
Patch clamp characterization of sodium channels expressed from rat brain cDNA.
1987,
Pubmed
,
Xenbase
Zagotta,
Shaker potassium channel gating. III: Evaluation of kinetic models for activation.
1994,
Pubmed
,
Xenbase
Zimmerberg,
Polymer inaccessible volume changes during opening and closing of a voltage-dependent ionic channel.
,
Pubmed
Zimmerberg,
Solute inaccessible aqueous volume changes during opening of the potassium channel of the squid giant axon.
1990,
Pubmed