Related Experiment Video
Updated: May 4, 2026
10:35
Two-photon Calcium Imaging in Neuronal Dendrites in Brain Slices
Published on: March 15, 2018
11.0K
Different calcium sources control somatic versus dendritic SK channel activation during action potentials
1Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra 0200, Australian Capital Territory, Australia.
Summary
Small-conductance calcium-activated potassium (SK) channels in dendrites and spines regulate calcium influx during action potentials (APs), tightly coupled to R-type channels. Somatic SK channels are less coupled to their calcium sources.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
- Ion Channel Function
Background:
- Small-conductance calcium-activated potassium (SK) channels are crucial for neuronal excitability.
- SK channels at the soma influence medium afterhyperpolarization (mAHP).
- Emerging evidence suggests SK channels regulate dendritic NMDA receptor activity.
Purpose of the Study:
- To investigate SK channel activation in dendritic spines and dendrites during action potentials (APs) in rat cortical pyramidal neurons.
- To compare dendritic SK channel activation with somatic SK channel activation.
- To identify the calcium sources for SK channel activation in different neuronal compartments.
Main Methods:
- Confocal calcium imaging in rat cortical pyramidal neurons.
- Pharmacological inhibition of SK channels using apamin.
- Blockade of voltage-dependent calcium channels (VDCCs) and intracellular calcium stores.
Main Results:
- SK channel inhibition increased dendritic and spine calcium influx during backpropagating APs (~40%).
- This increase was dependent on R-type VDCCs, not N- or P/Q-type VDCCs or intracellular calcium release.
- Somatic SK channel activation by APs involved various VDCCs, indicating weak coupling to calcium sources.
Conclusions:
- Dendritic and spine SK channels regulate calcium influx during backpropagating APs in a distance-dependent manner, coupled to R-type VDCCs.
- Somatic SK channels activated by APs exhibit weak coupling to a diverse set of VDCCs.
- These findings highlight distinct roles and calcium source coupling for SK channels in different neuronal compartments.
Related Concept Videos
01:19The Role of Ion Channels in Neuronal Computation
3.2K
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....
3.2K
01:27Feedback Regulation of Calcium Concentration
2.9K
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
2.9K
01:30Ligand-Gated Ion Channel Receptor: Gating Mechanism
4.6K
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
4.6K
01:26Voltage-gated Ion Channels
11.2K
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...
11.2K
01:16Calmodulin-dependent Signaling
5.0K
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
5.0K
01:29Relaxation of Skeletal Muscles
9.6K
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
9.6K