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Modification of delayed rectifier potassium currents by the Kv9.1 potassium channel subunit
F C Richardson1, L K Kaczmarek
1Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
Hearing Research
|August 30, 2000
Summary
The Kv9.1 potassium channel subunit modifies the electrical properties of Kv2.1 channels, impacting neuronal firing patterns in auditory pathways. This interaction influences how neurons respond to sound stimuli.
Area of Science:
- Neuroscience
- Molecular Biology
- Electrophysiology
Background:
- Potassium channels are crucial for neuronal electrical properties and action potential patterns in auditory pathways.
- The Kv9.1 gene encodes a potassium channel alpha subunit found in neurons, including the inferior colliculus.
- Kv9.1 alone does not form functional channels but can modulate other subunits when co-expressed.
Purpose of the Study:
- To investigate the functional effects of co-expressing Kv9.1 with the Kv2.1 potassium channel subunit.
- To determine how Kv9.1 alters the kinetics and voltage-dependence of Kv2.1 channel activity.
- To explore the potential impact of Kv9.1/Kv2.1 co-expression on neuronal firing patterns.
Main Methods:
- Co-expression of Kv9.1 and Kv2.1 in Xenopus oocytes.
- Electrophysiological recordings to measure potassium currents.
- Application of tetraethyl ammonium ions (TEA) to assess channel blocker sensitivity.
- Computer simulations of model neurons to predict firing pattern effects.
Main Results:
- Kv9.1 co-expression slowed the activation rate of Kv2.1 currents.
- Co-expression resulted in a biphasic voltage-dependence of Kv2.1 current amplitude, unlike the monotonic relationship seen with Kv2.1 alone.
- Kv9.1 induced an apparent negative shift in the voltage-dependence of Kv2.1 activation and inactivation.
- Higher TEA concentrations abolished the biphasic current amplitude dependence.
Conclusions:
- Kv9.1 significantly alters the biophysical properties of Kv2.1 channels, including activation kinetics and voltage-dependence.
- The observed changes suggest Kv9.1 can modulate neuronal excitability and firing patterns, potentially inhibiting firing during sustained depolarization or enhancing high-frequency following.
- These findings highlight the role of potassium channel subunit interactions in shaping auditory pathway function.
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Related Concept Videos
01:41Action Potentials
Overview
01:24Non-gated Ion Channels
Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
01:19The Role of Ion Channels in Neuronal Computation
A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
01:26Voltage-gated Ion Channels
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
01:28Action Potential: Phases of Stimulation
The action potential is a complex electrical event that occurs in excitable cells, such as neurons and muscle cells. It consists of several distinct phases, each with specific characteristics.
Resting Phase:
In this phase, the cell's membrane is at its resting potential, typically around -70 millivolts (mV) for neurons. Inside the cell, there is a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+). Voltage-gated sodium channels are closed, and...
Resting Phase:
In this phase, the cell's membrane is at its resting potential, typically around -70 millivolts (mV) for neurons. Inside the cell, there is a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+). Voltage-gated sodium channels are closed, and...
01:26Voltage-gated Ion Channels
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...