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Physiology Exam 5 > Voltage-Gated Ion Channels > Flashcards

Voltage-Gated Ion Channels Flashcards

1
Q

2 subunit types of VG Na channels

A

alpha and beta

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2
Q

Alpha subunit of VG Na channel

A

Modeled as 4 internal repeats

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3
Q

Voltage sensor of VG Na channel

A

TM4 (S4)

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4
Q

What part forms the channel of VG Na channel?

A

P loop, H5 or SS1-SS2

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5
Q

VG Na channel inactivation gate is located between?

A

Repeat III and IV

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6
Q

Activation of VG Na channel is dependent on?

A

Voltage (requires adequate depolarization)

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7
Q

Open probability of VG Na channel is dependent on?

A

Time (rapid inactivation)

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8
Q

How long does it take for VG Na channel to go from active to inactive?

A

1 ms

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9
Q

Inactivated state of VG Na channel is dependent on?

A

Time and voltage → requires time at negative (hyperpolarized) potential to de-inactivate

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10
Q

VG Na channel is blocked by?

A
  1. Local anesthetics (ex: lidocaine)

2. Tetrodotoxin

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11
Q

If the membrane does not repolarize, what happens to VG Na channel?

A

Remains inactivated for extended time

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12
Q

Mechanism of VG Na channel inactivation gate is called?

A

Hinged lid

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13
Q

Cytoplasm loop of VG Na channel (hinged lid) is made of?

A
  1. Isoleucine
  2. Phenylalanine
  3. Methionine
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14
Q

In a cell with mutated VG Na channel which remains open, what happens to membrane potential?

A

Stays near E(Na)

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15
Q

HYPP stands for?

A

Hyperkalemic Periodic Paralysis

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16
Q

Hyperkalemia means?

A

High blood potassium

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17
Q

HYPP is caused by?

A

Defect in sodium channels → high blood K is secondary

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18
Q

What is the defect in Na channels in HYPP?

A

Rapid deactivation → no refractory period

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19
Q

K channels are sensitive to?

A

Voltage and Calcium

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20
Q

T of VG K channels determines?

A

Tetramerization → family specific

Has phosphorylation sites

21
Q

Inactivation latch of VG K channels is located?

A

Between loops 4 and 5

22
Q

Functional characteristics (activation, open probability and inactivation) of VG K channel are the same as?

A

VG Na channel

23
Q

VG K channels are blocked by?

A
  1. Antiarrhythmics
  2. Toxins
  3. Dendrotoxin
  4. Charybdotoxin
  5. Agitoxin
24
Q

VG K channel inactivation latch is called?

A

Ball and chain

25
Q

Which inactivation method is more rapid, hinged lid or ball and chain?

A

Hinged lid

26
Q

Why is ball and chain inactivation slower than hinged lid?

A

Longer chain (chain length varies among K channels)

27
Q

Activated K channel has what effect on membrane potential?

A

Decreases membrane potential

28
Q

If drug blocks K channel, what happens to cell?

A

Will depolarize and have decreased ability to repolarize

29
Q

Action potential comes from?

A

Changing conductances over time

30
Q

Resting membrane potential is regulated by?

A

Basal conductances

31
Q

What induces depolarization to threshold?

A

Agonist

32
Q

Agonist-induced anion channels do what?

A

Reduce depolarizing impact of stimulating neurotransmitters (prevents reaching threshold)

33
Q

V-sensitive Ca channels are important for action potential in what cels?

A

Cardiac and nerve

34
Q

What type of channel is important for excitation-secretion coupling?

A

V-sensitive Ca channels

35
Q

V-sensitive Ca channels have intracellular regulation by?

A
  1. Kinases
  2. Ca
  3. G-proteins
36
Q

Inactivation timer of V-sensitive Ca channels

A

TM6 of repeat I

37
Q

Voltage sensor of V-sensitive Ca channels

A

TM4

38
Q

Subunit types of Ca(V) channels

A
  1. Alpba
  2. Beta
  3. Gamma
  4. Delta
39
Q

Ca(V) channel functional characteristics

A

same as others

40
Q

Ca(v)1.x is what type?

A

L-type (long)

41
Q

Ca(V)1.x modulated by?

A

Dihydropyridines

42
Q

Dihydropyridines are a target for?

A

Drug interference with cardiac modulation

43
Q

Ca(V)2.x is what type?

A

P/N/R-type (neither)

44
Q

Ca(V)2.x is found in?

A

Dorsal root ganglion (pain interaction)

45
Q

Ca(V)2.x is blocked by?

A
  1. Agatoxin
  2. Conotoxins
  3. SNX-482
46
Q

Ca(V)3.x is what type?

A

T-type (transient)

47
Q

Ca(V)3.x is found in?

A

CNS (anticonvulsant target)

48
Q

Ca(V)3.x is blocked by?

A

Kurtoxin (from scorpion)

49
Q

Antiarrhythmic drugs target?

A

Rapidly activating cardiac K channels

Physiology Exam 5 (11 decks)

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