Manipulating cardiac function

Question 1

What is EC50

Answer 1

Concentration of drug that produces 50% of maximal response (how much of the drug we need to ilicit a response)

Question 2

What will happen to the dose response curve in the presence of a competitive antagonist

Answer 2

Parrallel shift to the right, EC50 will increase due to the presence of a competitive antagonist

Question 3

Cardiac output

Answer 3

= heart rate x stroke volume

Question 4

Which neurotransmitter is released following sympathetic innervation of the heart

Answer 4

Noradrenaline, increasing HR and contraction force

Question 5

Which neurotransmitter is released following parasympathetic innervation of the heart

Answer 5

Acetylcholine, can reduce HR and force of contraction

Question 6

Where does noradrenaline act

Answer 6

Binds to alpha and beta receptors

Acts in the heart tissue and in the vasculature

Question 7

What does Isoprenaline bind to

Answer 7

Only binds beta receptors

Question 8

What is the affect of isoprenaline on HR and BP

Answer 8

Increases Hr, but decreases BP

Question 9

What does the introduction of isoprenaline tell you about the role of beta receptors in the heart tissue and vasculature

Answer 9

• Beta receptors in heart tissue increase HR

- Beta receptors in the vasculature are vasodilators

Question 10

What are the roles of alpha, beta 1 and beta 2 receptors

Answer 10

• Alpha= cause vasoconstriction
• Beta 1= in the heart, increase HR and force of contraction
• Beta 2= in the vasculature, cause vasodilation

Question 11

What is prazosin

Answer 11

Adrenergic antagonist (alpha 1 blocker)

Question 12

When prazosin was added the affect of noradrenaline was unchanged, what does this tell you

Answer 12

No alpha 1 receptors in the heart

Question 13

What do alpha 1 receptors do

Answer 13

vasoconstriction

- so prazosin can block the BP increase from noradrenaline

Question 14

What is propanolol

Answer 14

An adrenergic antagonist (beta 1 and 2 blocker)

Question 15

How does propanolol

Answer 15

Will block noradrenaline, menaing HR does not change

Question 16

Propanolol has little affect on BP what does this mean about noradrenaline and vasculature

Answer 16

Shows the dominant affect of noradrenline in the vasculature is alpha related

Question 17

What is atenolol

Answer 17

adrenergic antagonist (beta 1 blocker)

Question 18

What happens to the affect of noradrenaline in the presence of Atenolol

Answer 18

Affect on HR is reduced, shows that Beta 1 receptors are located in cardiac tissue (also reduction in BP likely due to reduced cardiac output)

Question 19

From these tests, what do B-adrenoreceptors regulate

Answer 19

Regulate HR (B1 or B2)

Question 20

What does blocking B-adrenreceptors also lead to?

Answer 20

Increase noradrenaline’s alpha 1 effect (slight increase to vasoconstriction)

Question 21

What do Beta 1 and Beta 2 receptors regulate resepectivley

Answer 21

B1 adrenoreceptor in heart

Vasodilation regulated by B2

Question 22

Describe the full affects noradrenaline (sympathetic ) has on the alpha and beta receptors

Answer 22

A1- blood vessels, constriction
A2- Blood vessels, constriction/relaxation
B1- heart, increased HR, increased contractility
B2- blood vessels, relaxation (also relaxes airways)

Question 23

Describe the full affects of acetylcholine (parasympathetic) has on muscarinic receptors

Answer 23

M2- decreases HR, decreases contractility

Question 24

What does atropine do

Answer 24

blocks muscarinic receptors, acting as an antagonist for acetylcholine

Question 25

What does angiotensin II do

Answer 25

increases blood pressure by inducing vasoconstriction

Question 26

What blocks angiotensin II

Answer 26

Isosaratan