Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
Types of patch clamping
|
1. cell-attached patch clamping
2. whole-cell recording 3. inside-out patch reecording 4. outside-out recording |
|
|
What can block Vgated Na+ channels?
|
1. Cs+
2. TTX 3. saxotoxin 4. alpha-toxin |
|
|
The size of currents are _______, reaching discrete values that suggest ion flux through individual, open ion channels.
|
stereotyped
|
|
|
According to the patch clamp method, what is the microscopic current for one Vgated Na+ channel?
|
2 pA
|
|
|
When Vm < E(Na), then ____ current is detected.
|
Inward
|
|
|
When Vm > E(Na) then ____ current is detected.
|
outward
|
|
|
The ________ Na+ current measured by Hodgkin and Huxley does indeed arise from the ________ effect of many thousands of ________ Na+ currents, each representing the opening of a single voltage-sensitive Na+ channel.
|
1. macroscopic
2. aggregate 3. microscopic |
|
|
When measuring the microscopic outward current of K+, you have to use _____.
|
TTX to block Na+ current.
|
|
|
What closes Vgated channels?
|
Hyperpolarization.
|
|
|
Vgated Na+ channels have 3 states. What are they?
Note: Vgated K+ only has 2 states |
1. open
2. inactivated 3. closed |
|
|
Which toxins block Vgated Na+ channels?
a. TTX b. Saxitoxin c. alpha-toxin (scorpion) d. beta-toxin (scorpion) |
a, b, c
note: alpha-toxin causes slow inactivation of Na+ channels |
|
|
What toxin causes slow inactivation of Na+ channels, resulting in a prolonged AP?
|
alpha-toxin (scorpions)
|
|
|
Which toxin shifts the voltage dependence of Na+ channel activation, causing an influx of Na+ at a lower voltage? What is the effect?
|
beta-toxin.
Membrane depolarizes at a lower threshold--muscles will lock up! |
|
|
What factors result in ion channel diversity?
A. mRNA splicing B. RNA editing C. post-translational mods D. channels are made of subunits, making combos possible |
all of the above
|
|
|
How many Na+ channel genes have been discovered so far? K+?
|
10 Na+ channels, 100 K+ channels
|
|
|
Which Vg channel is a target for local anesthetics?
|
persistent Na+ channels which don't inactivate
|
|
|
ACh receptors allow which ions through (ionotropic, quick)
|
Na and K
|
|
|
What blocks V-gated K+ channels?
|
1. dendrotoxin
2. apamin 3. charybdotoxin |
|
|
What's the difference between KV2.1 and KV4.1?
|
KV2.1 takes minutes to inactivate, wherease KV4.1 takes seconds to activate.
|
|
|
What Vgated K+ channel inactivates faster than KV2.1 and KV4.1?
|
HERG
|
|
|
What type of Vgated K+ channel is primarily responsible for the membrane resting potential?
|
2-P K+ channels; they have little sensitivity to voltage signalling, but are sensitive to chemical signalling.
|
|
|
How selective are nicotinic ACh receptors?
|
Not very; they allow Na+ and K+ to diffuse.
|
