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Cardiovascular > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

The intracellular concentration of what element affects the contraction of smooth muscle?

A

Calcium

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2
Q

Where is calcium stored inside the cell?

A

Sarcoplasmic reticulum

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3
Q

How does calcium enter the cell?

A

The membrane is impermeable to calcium. It enters though ion channels, we focus on the voltage gated calcium channels.

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4
Q

What happens when the voltage gated calcium channels are activated?

A

Calcium enters the cell and a second messenger molecule is produced that causes the sarcoplasmic reticulum to release calcium

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5
Q

What does calcium bind to inside the cell and what is the process that leads to contraction?

A

Calcium bind to calmodulin. This calcium calmodulin complex reacts with MLCK activating it. This then reacts with myosin. Actin can then slide over the myosin = contraction.

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6
Q

How is nitric oxide produced in endothelial cells?

A

Calcium enters the cells and binds with calmodulin. This complex then activates the enzyme eNOS which allows the production of NO.

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7
Q

What is the affect of NO on vascular smooth muscle cells?

A

It causes smooth muscle relaxation

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8
Q

Explain the mechanism of NO that leads to relaxation of vascular smooth mucle

A

NO can readily diffuse across the phospholipid membrane. NO activates the enzyme guanylate cyclase which converts GTP to cGTP.

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9
Q

What is the affect of NO on potassium channels?

A

NO opens calcium dependent potassium channels. This makes the cell’s net charge more negative.

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10
Q

What class of drugs high-jack the NO mechanism?

A

Organic nitrates e.g. GTN (glyceryl trinitrate)

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11
Q

What is the affect of organic nitrates?

A

The relax ALL types of smooth muscle

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12
Q

What is the affect of organic nitrates on the venous side of circulation?

A

Venorelaxation - increases the ability of veins to store blood. Increase in blood in the venous circulation means less blood is returned to the heart (decreased preload).

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13
Q

Why do organic nitrates not change the arterial pressure?

A

The preload is decreased, decreasing the SV but CO remains the same due to increase in heart rate.

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14
Q

What is the affect of organic nitrates on the arteries?

A

Arterial dilation.

This decreases arterial pressure, decreasing afterload, resulting in reduced oxygen demand of the heart.

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15
Q

Explain the concept of pulse range deflection and the affect of organic nitrates

A

When arteries divide in two the V shape at the division causes a reverse pressure wave that is sent back to the heart making it work harder. Arterial dilation as a result of arterial smooth muscle relaxation, reduces this effect.

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16
Q

Where do organic nitrates redirect blood to?

A

The ischaemic zones

17
Q

By what three mechanisms do organic nitrates decrease myocardial oxygen requirement, helping to relieve angina?

A
  1. Decrease the preload
  2. Decrease afterload
  3. Increase perfusion of the ischaemic zone
18
Q

How do organic nitrates increase prefusion of ischaemic zones?

A

Dilate collateral branches that start to appear between the healthy and diseased branches of the artery. Also, the arterioles downstream of the blockage are dilated to the max.

19
Q

What is the condition that organic nitrates is used in?

A

Angina

20
Q

Give two main examples of organic nitrates

A

Glyceryl trinitrate (GTN) and isosorbide mononitrate

21
Q

How do ACE inhibitors work?

A

Block the conversion of angiotension I to angiotension II

22
Q

How do AT1 receptor antagonists work?

A

Block the agonist action of angiotension II at AT1 receptors in a competitive manner

23
Q

Give an example of an ACE inhibitor

A

Lisinopril

24
Q

Given an example of an AT1 receptor antagonist

A

Losartan

25
Q

What are the main affects of ACEI?

A

Venous dilatation = decreased preload
Arterial dilatation = decreased afterload and TPR
Blood pressure and cardiac load are decreased
Reduces release of aldosterone

26
Q

What is the affect of B-blockers?

A

Blocks the effect of adrenalin on the heart.
Decrease myocardial oxygen requirement
Counter elevated sympathetic activity associated with ischaemic pain
Increase the length of diastole, improving perfusion of the left ventricle

27
Q

How do B-blockers treat hypertension?

A

Reduce cardiac output
Reduce renin release from the kidneys
CNS action that reduces sympathetic activity

28
Q

How do calcium antagonists work?

A

They prevent the opening of L-type channels in excitable tissues in response to depolarisation and therefore limit influx of calcium

29
Q

What do potassium channel openers do?

A

They open ATP-modulated K+ channels in vascular smooth muscle (mainly arterial)

30
Q

How do a1-adrenoceptor antagonists work?

A

Block vascular a1-adrenoceptors resulting in vasodilation

31
Q

How do diuretics work?

A

Act on the kidney to increase the excretion of Na, Cl and H2O and cause indirect relaxant effects on the vasculature

Cardiovascular (17 decks)

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