vasodilators

Question 1

what things relax vascular smooth muscle

Answer 1

• increasing cGMP, NO, nitrates, PDE5 inhibitors
• decreasing intracellular Ca
• Ca channel blockers (CCBs)
• increasing cAMP in vascular cells (cAMP increases inactivation of myosin light chain kinase)

Question 2

what is the purpose of vasodilators

Answer 2

• improve CO
• reduce edema and effusions

Question 3

vasodilators can affect arterioles and ?

Answer 3

venous capacitance vessels

Question 4

what drugs are vasodilators

Answer 4

• ACEI
• Nitrites
• Hydralazine
• CCBs
• alpha blockers

Question 5

what drug that acts through NO is most effective in CHF secondary to mitral valve insufficiency

Answer 5

Hydralazine

Question 6

Hydralazine dilates ____ but not _____

Answer 6

arterioles
not veins

Question 7

symptoms of Hyrdalazine toxicity

Answer 7

• V+, anorexia, tachycardia, sweating, hypotension (Cats)
• ischemic arrythmias, decompensation

Question 8

what happens to nitrate compounds

Answer 8

they get converted into NO

Question 9

Nitrates preferentially dilate ?

Answer 9

veins but they also dilate arteries

Question 10

effect of nitrates (NO) on myosin light chains

Answer 10

decreases phosphorylation

Question 11

these drugs have limited use in VetMed and have questionable efficacy in dogs & cats; all uses are extra label

Answer 11

Nitrates

Question 12

what are the uses for Nitroglycerin

Answer 12

• pulmoney edema associated w/ HF

Question 13

What nitrate dugs have potential for tolerance

Answer 13

• Nitroglycerin
• Isosorbide dinitrate
  avoid intermittent use

Question 14

of the 3 nitrate drugs (nitroglycerin, isosorbide dinitrate, sodium nitroprussidae) which one is a potent vasodilator and also doesn’t cause tolerance

Answer 14

Sodium nitroprusside

Question 15

how is Sodium nitroprusside administered

Answer 15

CRI, constant infusion

Question 16

what vasodilator is used in patients with pulmonary edema associated w/ HF and hypertensive crisis

Answer 16

Sodium nitroprusside

Question 17

what vasodilator is used to treat pulmonary edema associated with HF

Answer 17

Nitroglycerin

Question 18

what are the two important functions of intracellular calcium

Answer 18

• triggers muscular contraction in myocardium + vascular sm
• needed for the pacemaker activity of the SA node and for conduction through the AV node

Question 19

what opens the heart & vascular smooth muscle Ca channels? what closes them?

Answer 19

• opened by beta adrenergic stimulation to enhance calcium entry
• closd by CCBs to inhibit calcium entry

Question 20

orally active drugs that bind L-type channels in the myocardium and vascular smooth muscles

Answer 20

CCBs

Question 21

CCBs will relax all smooth muscles that depend on _____ for normal resting tone & contraction

Answer 21

calcium

Question 22

what are the major cardiac effects of CCBs (3)

Answer 22

• negative inotropic effects (decreased contractility)
• reduced impulse generation in SA node
• slowed AV node conduction

Question 23

long acting dihydropyridine Ca channel blocker that causes vasodilation w/out significant cardiac effects

Answer 23

Amlodipine besylate

Question 24

vasodilator DOG in hypertensive cats , all uses are extra label

Answer 24

Amlodipine besylate

Question 25

what kind of metabolism does Amlodipine besylate undergo

Answer 25

hepatic

Question 26

what does Dilitazem do

Answer 26

depresses SA and AV node, causes cardiac contractile depression

Question 27

what condition is treated using Dilitazem in cats and in dogs (different)

Answer 27

cats - hypertrophic cardiomyopathy dogs - supraventricular tachycardia

Question 28

what drug needs to be careful when used in nursing mothers and why

Answer 28

Diltiazem b/c it is excreted in milk

Question 29

what is the main difference between the effects of Amlodipine and Dilltiazem

Answer 29

* Amlodipine causes more significant vasodilation and reflex tachycardia * Diltiazem causes depression of SA and AV node and negative inotropic

Question 30

how do phosophodiesterase 5 inhibitors (PDE5) cause vasodilation

Answer 30

inhibition of cGMP, less cGMP = vasodilation

Question 31

what condition is Sildenafil useful in treating

Answer 31

pulmonary hypertension in dogs

Question 32

how do alpha 1 adrenergic antagonists work to decrease blood pressure

Answer 32

* blocking alpha one reduces vasoconstriction in arteries and veins caused by NE * blood pressure falls due to a decrease in peripheral resistance

Question 33

what is the primary use of Prazosin

Answer 33

treatment of functional urethral obstruction in dogs

Question 34

how does prazosin elicit less of a tachycardic reflex

Answer 34

prazosin only targets alpha one receptors, not alpha 2

Question 35

what are the adverse effects of prazosin

Answer 35

* hypotension * sodium and water retention (increased renin)

Question 36

what is the BA of Diltiazem in dogs vs cats

Answer 36

25% in dogs, 50-80% in cats (PO)

Question 37

of all the vasodilators, which drug has the greatest binding to plasma proteins

Answer 37

Diltiazem, 70-75% bound to plasma proteins

Question 38

where is Diltiazem metabolized

Answer 38

liver

Question 39

this drug decreases the membrane Ca current, causes long-lasting relaxation of vascular smooth muscles and decreases cardiac contractility, automaticity and conduction

Answer 39

Amlodipine besylate (CCBs)