Cell volume and membrane stretch independently control K+ channel activity
Sofia Hammami1, Niels J Willumsen, Hervør L Olsen
1Department of Biology, University of Copenhagen, Denmark.
The Journal of Physiology
|March 18, 2009
Summary
Cell volume changes regulate potassium channels, but not through membrane stretch. KCNQ1 and BK channels show distinct responses, indicating stretch and volume sensitivity are independent mechanisms.
Area of Science:
- Cellular physiology
- Ion channel biophysics
- Membrane transport
Background:
- Cell volume changes regulate various potassium channels, including KCNQ and Ca(2+)-activated channels.
- This regulation is often attributed to membrane stretch, a hypothesis this study investigates.
Purpose of the Study:
- To investigate the role of membrane stretch in the volume sensitivity of KCNQ1 and BK potassium channels.
- To determine if membrane stretch and cell volume changes are linked regulatory mechanisms.
Main Methods:
- Xenopus oocytes expressing KCNQ1 and BK channels were used.
- Cell-attached patch clamp recordings were performed under varying hydrostatic pressure to simulate membrane stretch.
- Macroscopic currents were measured to assess channel activity.
Main Results:
- BK channels, though volume-insensitive, showed increased current with negative hydrostatic pressure (membrane stretch).
- KCNQ1 channels, which are volume-sensitive, were unaffected by membrane stretch.
- These findings differentiate the mechanisms of BK and KCNQ1 channel regulation.
Conclusions:
- Activation of BK channels by membrane stretch is distinct from cell swelling-induced stress.
- Activation of KCNQ1 channels by cell volume increase is not mediated by membrane tension.
- Membrane stretch sensitivity and cell volume sensitivity are independent regulatory mechanisms for potassium channels.
More Related Videos
11:42Reconstitution of a Transmembrane Protein, the Voltage-gated Ion Channel, KvAP, into Giant Unilamellar Vesicles for Microscopy and Patch Clamp Studies
Published on: January 22, 2015
10:08Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
Published on: December 9, 2022
Related Concept Videos
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...
01:26Voltage-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...
01:18Patch Clamp
Many fundamental cell functions such as muscle contraction and nerve transmission rely on the electrical signals produced by the movement of positively and negatively charged ions across the cell membrane. One competent method to record current flowing across the whole cell or single ion channel is the patch-clamp technique.
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
01:15Resting Potential Decay
The resting membrane potential of a neuron (-70mV) is sustained due to the selective ion permeability of the membrane. At the resting potential, the membrane is slightly permeable to ions like sodium (Na+) and chloride (Cl−) and highly permeable to potassium ions (K+). Differences in the ions' concentration inside the cell compared to the outside are maintained by membrane transport proteins like channels and pumps.
At rest, the K+ is the main ion that moves across the membrane through...
At rest, the K+ is the main ion that moves across the membrane through...
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.
01:15Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...