Ion Channels

Question 1

What is a patch clamp?

Answer 1

Direct recording of ionic currents from cell surface ion channels.

Question 2

What are planar lipid bilayer techniques?

Answer 2

Direct recording of ionic currents from intracellular ion channels.

Question 3

What are the machines used in a planar lipid bilayer analysis?

Answer 3

Amplifier, digester and computer.

Question 4

What opens the channel?

Answer 4

Voltage, Ligand, Stretch and Light.

Question 5

How does voltage open a channel?

Answer 5

Changing membrane voltage in depolarizing or hyperpolarizing direction.

Question 6

How does a ligand open a channel?

Answer 6

Neurotransmitter binds and activates from outside cell.

Question 7

How does a 2nd messenger ligand open a channel?

Answer 7

A second messenger binds at cytosolic surface and activates the channel.

Question 8

What is an example of a ligand channel?

Answer 8

The glutamate receptor.

Question 9

What is an example of a 2nd messenger ligand channel?

Answer 9

Ryanodine receptor.

Question 10

What are stretch channels?

Answer 10

Mechanosensitive channels.

Question 11

What are examples of light channels?

Answer 11

Channelrhodopsin.

Question 12

What is the probability of channel gating equation?

Answer 12

Popen= Topen/Ttotal.

Question 13

Define affinity.

Answer 13

Measure of binding.

Question 14

Define efficacy.

Answer 14

How easy it is to elicit a response.

Question 15

What is single channel conductance?

Answer 15

How good a channel is at letting current through.

Question 16

What is the macroscopic ionic current (whole cell current) equal to?

Answer 16

The product of the number of channels within the membrane area, the unitary current and the probability of the channel opening.

Question 17

How can we measure which ions flow through the channel?

Answer 17

Clamp voltage across membrane patch and measure open channel as a function of voltage.

Question 18

What is an inhibitor of sodium ion channels?

Answer 18

Tetrodotoxin

Question 19

What is an inhibitor of potassium ion channels?

Answer 19

Tetraethylammonium

Question 20

What happens if the transport of calcium through ion channels dysfunctions?

Answer 20

Ischemia, cardiac arrhythmmias and malignant hypertension.

Question 21

What can channelopathy of the RyR cause?

Answer 21

Catecholaminergic polymorphic ventricular tachycardia.

Question 22

What type of disease is CPVT?

Answer 22

An inheritable autosomal dominant condition.

Question 23

What are symptoms of CPVT?

Answer 23

Dizzy spells, fainting episodes and sudden cardiac death.

Question 24

What causes the underlying mechanism of CPVT?

Answer 24

69 point mutations were identified in the RyR2 gene.

Question 25

What condition is ryanodine receptor type 1 channel mutations associated with?

Answer 25

Malignant Hyperthermia (MH).

Question 26

What are the symptoms of MH?

Answer 26

Muscle rigidity, high fever, rapid HR and increased acid levels in the blood.

Question 27

What is the underlying mechanism of MH?

Answer 27

Point mutations in the gene coding for RyR1.