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Integrated Drug Structure, Function, and Therapeutics Winter Term > Calcium channel agents > Flashcards

Calcium channel agents Flashcards

1
Q

What happens in a cardiomyocyte dependent on calcium?

A
  1. Gap junctions facilitate communication of APs and cause depolarization
  2. Voltage-gated Na channels open
  3. 75% of Na channels inactivate, and K channels open (25% of slow Na channels remain open. Ca channels also open.
  4. The Ca comes in. It triggers the release of more Ca from the SR
  5. Ca binds to troponin and activates contractile complex.
  6. Ca is removed via the Ca-uptake SR
  7. Pumps assist (Na/Ca exchanger w/o ATP, and Na/K ATPase).
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2
Q

What does the Na-Ca exchanger (NCX) do?

A

3 Na enters, and 1 Ca exit the cell

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3
Q

What does the Ca ATPase do?

A

Calcium can go in and out wth the assistance of ATP

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4
Q

What does the K/Na ATPase do?

A

3 Na exit the cell, 2 K enter the cell

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5
Q

What types of pumps are in the SR?

A

SERCA2 complex - allows Ca to enter the SR

RyR2 receptors - When activated by PKA, allow Ca to exit

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6
Q

What happens when ATP is hydrolyzed to ADP on a myosin filament?

A

The head of myosin has unattached from the actin.

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7
Q

When the ATP is hydrolyzed, what does the myosin head do?

A

It attaches to the actin

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8
Q

Once the myosin head attaches to the actin, what happens next?

A

The ADP and P cause the myosin head to change position and the actin to move.

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9
Q

Once the actin filament moves, what happens?

A

ATP binds and the myosin head returns to a resting position

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10
Q

What does troponin do?

A

It attracts Ca to bind, which then pull tropomyosin away which exposes myosin binding sites.

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11
Q

How many subunits are in a voltage-gated calcium channel?

A

4-5

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12
Q

What are the different types of voltage-gated calcium channels?

A

cardiac, skeletal, smooth muscle, neurons, endocrine cells, bone

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13
Q

What is a dihydropyridine receptor (DHPR)?

A

An L-type (long) calcium voltage-gated channel that control contraction both in the heart and in skeletal muscle.

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14
Q

Once a voltage-gated calcium channel is opened, what happens to the calcium?

A

The calcium triggers release of more Ca from the SR

The calcium

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15
Q

What do want to have happen in the nodal cells when you use a Ca-channel antagonist?

A

Want to inhibit the regeneration of a new impulse

Want to decrease the heart rate

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16
Q

What do you want to have happen in the myocardial cells when you use a Ca-channel antagonist?

A

Want to decrease contractility

17
Q

What do Ca-channel antagonists do?

A
  • Block movement of Ca into the muscle cells of arteries
  • Arteries become larger
  • Relaxes blood vessels, decreases heart’s pumping strength
  • Treat high bp, angina, arrhythmia
  • high dose associated with myocardial infarction, GI hemorrhage, and mortality

Integrated Drug Structure, Function, and Therapeutics Winter Term (18 decks)

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