Lecture 18: Vasodilators

Question 1

Describe polyphosphoinositide signaling

Answer 1

1. Gq activates membrane phospholipase C
2. Hydrolyzes IP3/DAG
3. IP3 releases Ca2+
4. DAG stimulates PKC- IP3 dephosphorylated, DAG broken down and Ca2+ pumped out

Question 2

What vasodilators increase cGMP and cause relaxation of vascular smooth muscle

Answer 2

NO, nitrprusside, organic nitrates, and PDE V inhibitors

Question 3

What vasodilators decrease intracellular ca2+ and therefore relax vascular smooth muscle

Answer 3

CCB’s

Question 4

CAMP increases the inactivation of ___kinase

Answer 4

Myosin light chain kinase

Question 5

In order to promote relaxation what must happen to myosin light chain

Answer 5

Dephosphorylate

Question 6

Vasodilators further improve ___ and reduce __ and ___ in heart failure patients

Answer 6

Cardiac output, edema and effusions

Question 7

Vasodilators that reduce arteriolar resistance are also used in treatment of ___

Answer 7

Hypertension

Question 8

How do ACE inhibitors effect vasodilation veins and arteries

Answer 8

arteries: +
Veins: +

Question 9

How do nitrites effect vasodilation of veins and arteries

Answer 9

Arteries: +
Veins: ++

Question 10

How does hydralazine effect vasodilation of arteries and veins

Answer 10

Arteries: +
Veins: -

Question 11

How do CCB’s effect vasodilation of arteries and veins

Answer 11

Arteries: ++
Veins: -

Question 12

How do alpha blockers effect vasodilation of arteries and veins

Answer 12

Arteries: +
Veins: +

Question 13

What species is hydralazine commonly used in

Answer 13

Dogs, cats and rarely horses

Question 14

Hydralazine dilates __ but not ___

Answer 14

Arteries but not veins

Question 15

What is hydralazine most effective in treating

Answer 15

HF secondary to mitral valve insufficiency

Question 16

Nitrates preferentially dilate ___ however dilate __ too

Answer 16

Veins, arteries

Question 17

What vasodilators act through nitric oxide

Answer 17

1. Hydralazine
2. Nitrates
   - nitroglycerin
   - isosorbide dinitrate
   - sodium nitroprusside

Question 18

What is nitroglycerin used for

Answer 18

Pulmonary edema associated with HF

**vasodilate veins over arteries so assists with Left side HF symptoms

Question 19

T or F: tolerance may develop with use of nitroglycerin

Answer 19

True

Question 20

T or F: isosorbide dinitrate may develop tolerance

Answer 20

True

Question 21

Which nitrate is a potent vasodilator that is administered as a constant infusion

Answer 21

Sodium nitroprusside

Question 22

With the use of sodium nitroprusside, ___ toxicity may develop in patients with compromised renal function

Answer 22

Cyanide

Question 23

T or F: tolerance develops with the use of sodium nitroprusside

Answer 23

False

Question 24

When is sodium nitroprusside used

Answer 24

Pulmonary edema associated with HF and emergent hypertensive crisis

Question 25

What are the two important functions of Ca2+

Answer 25

1. Trigger muscle contractions in myocardium and vascular smooth muscle 2, required for pacemaker activity of SA node and conduction through AV node

Question 26

How are vascular smooth muscle and heart calcium channels opened in the heart

Answer 26

B-adrenergic stimulation

Question 27

How are heart and vascular smooth muscle calcium channels closed

Answer 27

CCB’s inhibit calcium entry

Question 28

what channels do CCB’s act on

Answer 28

L-type channels

Question 29

What do CCB’s do to transmembrane calcium current

Answer 29

Decrease

Question 30

CCB’s cause a long lasting __ of vascular smooth muscle

Answer 30

Relaxation

Question 31

How do CCB’s effect cardiac contractility, automaticity and conduction

Answer 31

Decrease

Question 32

CCB’s will relax all smooth muscles that depend on calcium. ___ muscle is most sensitive but __, __, and __ is also relaxed

Answer 32

Vascular smooth muscle, but bronchiolar, gastrointestinal and uterine

Question 33

CCB’s preferentially dilate ___ over __

Answer 33

Arterioles, veins

Question 34

What are the major cardiac effects of CCB’s

Answer 34

1. Negative inotropic effect due to decreased contractility 2. Reduced impulse generation from SA node 3. Slowed AV node conduction

Question 35

What type of drug is amlodipine besylate

Answer 35

Long acting CCB

Question 36

What does amlodipine besylate do

Answer 36

Vasodilate

Question 37

Amlodipine besylate is the drug of choice for __

Answer 37

Hypertensive cats

Question 38

The use of amlodipine is cautioned when __ function is poor

Answer 38

Liver

Question 39

Amlodipine besylate can activate RAAS but this is reduced if concurrently used with

Answer 39

Enalapril (ACEi)

Question 40

What type of drug is diltiazem

Answer 40

CCB

Question 41

What does diltiazem do

Answer 41

Depresses AV and SA node for cardiac contractile depression

Question 42

When is diltiazem used

Answer 42

HCM in cats and supraventricular tachycardia in dogs and cats

Question 43

Which has a greater vasodilatory effect and causes reflex tachycardia: amlodipine or diltiazem

Answer 43

Amlodipine

Question 44

Which has a greater depression of SA and AV node, and negative inotropic effect: amlodipine or diltiazem

Answer 44

Diltiazem

Question 45

What type of drug is sildenafil

Answer 45

Selective inhibitor of cGMP specific PDE5

Question 46

How does sidenafil work

Answer 46

By decreasing elimination of cGMP produces vasodilation

Question 47

Sidenafil seems to be effective in ___ in dogs

Answer 47

Pulmonary hypertension

Question 48

What type or drug is prazosin

Answer 48

Alpha1 adrenergic antagonist

Question 49

When is prazosin used

Answer 49

1. Typically for functional urethrospasm in dogs 2. HF less characterized but can be considered when hydralazine is poorly tolerated

Question 50

How does prazosin work

Answer 50

Blocks alpha1 adrenergic receptors so opposes NE vasoconstriction and dilates both arteries and veins BP decreases

Question 51

Prazosin can cause reflex __

Answer 51

Tachycardia

Question 52

What are some adverse effects of prazosin

Answer 52

Hypotension, Na+ and H20 retention