Ion Channels Flashcards
What is a patch clamp?
Direct recording of ionic currents from cell surface ion channels.
What are planar lipid bilayer techniques?
Direct recording of ionic currents from intracellular ion channels.
What are the machines used in a planar lipid bilayer analysis?
Amplifier, digester and computer.
What opens the channel?
Voltage, Ligand, Stretch and Light.
How does voltage open a channel?
Changing membrane voltage in depolarizing or hyperpolarizing direction.
How does a ligand open a channel?
Neurotransmitter binds and activates from outside cell.
How does a 2nd messenger ligand open a channel?
A second messenger binds at cytosolic surface and activates the channel.
What is an example of a ligand channel?
The glutamate receptor.
What is an example of a 2nd messenger ligand channel?
Ryanodine receptor.
What are stretch channels?
Mechanosensitive channels.
What are examples of light channels?
Channelrhodopsin.
What is the probability of channel gating equation?
Popen= Topen/Ttotal.
Define affinity.
Measure of binding.
Define efficacy.
How easy it is to elicit a response.
What is single channel conductance?
How good a channel is at letting current through.
What is the macroscopic ionic current (whole cell current) equal to?
The product of the number of channels within the membrane area, the unitary current and the probability of the channel opening.
How can we measure which ions flow through the channel?
Clamp voltage across membrane patch and measure open channel as a function of voltage.
What is an inhibitor of sodium ion channels?
Tetrodotoxin
What is an inhibitor of potassium ion channels?
Tetraethylammonium
What happens if the transport of calcium through ion channels dysfunctions?
Ischemia, cardiac arrhythmmias and malignant hypertension.
What can channelopathy of the RyR cause?
Catecholaminergic polymorphic ventricular tachycardia.
What type of disease is CPVT?
An inheritable autosomal dominant condition.
What are symptoms of CPVT?
Dizzy spells, fainting episodes and sudden cardiac death.
What causes the underlying mechanism of CPVT?
69 point mutations were identified in the RyR2 gene.
