L12 - drugs affecting SNS II

Question 1

What are the indirect sympathomimetics drugs?

Answer 1

Amphetamine, Ephedrine, Tyramine

Question 2

Effects of indirect sympathomimetics

Answer 2

increase the availability of noradrenaline/adrenaline to stimulate adrenergic receptors, and there is no interaction between the drug and receptor

Question 3

Chemical structure similar to NA/A

Answer 3

Bronchodilatation (beta 2 adrenoceptor mediated action)

Question 4

Enter terminals by uptake 1

Answer 4

Increase mean arterial BP (alpha 1 adrenoceptor mediated action)

Question 5

Inhibit NA uptake 1

Answer 5

Increase heart rate and force (beta 1 adrenoceptor mediated action)

Question 6

Displace NA/adrenaline from storage vesicles

Answer 6

Decrease gut motility (alpha 1 adrenoceptor mediated action)

Question 7

Effects of cocaine

Answer 7

Blocks the reuptake of NA by blocking the reuptake transporter (NET, DAT and SERT)

Question 8

Impramine

Answer 8

• Blocks the reuptake of NA
• Sodium channel blocker (contributes to cardio toxicity)
• Anti-muscarinic
• Anti-histamine

Question 9

Direct sympathomimetics

Answer 9

Drugs that have direct agonist action on adrenergic receptors

Question 10

Smooth muscle

Answer 10

Noradrenaline>Adrenaline>Isoprenaline

Question 11

Cardiac muscle

Answer 11

Isoprenaline>Adrenaline>Noradrenaline

Question 12

Isoprenaline

Answer 12

a medication used for the treatment of bradycardia (slow heart rate)

Question 13

What are adrenoceptors?

Answer 13

They are a class of G protein-coupled receptors that are targets for the catecholamines, especially noradrenaline and adrenaline

Question 14

For heart, noradrenaline acts on which type of receptors? (from sympathetic fibres)

Answer 14

Presynaptic alpha 2, postsynaptic beta 1

Question 15

For other tissues, noradrenaline acts on which type of receptor? (from sympathetic fibres)

Answer 15

Presynaptic alpha 2, postsynaptic alpha 1

Question 16

For most tissues (in severe situation), NA/Adrenaline from adrenal medulla, acts on what receptor?

Answer 16

Extra synaptic beta 2

Question 17

Where is alpha 1 receptor located?

Answer 17

It is located at the postsynaptic in all tissues except for the HEART

Question 18

Where is alpha 2 receptor located?

Answer 18

It is located at the presynaptic, wide spread distribution (all tissues) (inhibition of transmitter release) - -ve feedback control

Question 19

Where is beta 1 receptor located?

Answer 19

It is located at the postsynaptic of the heart - increase rate and force of contraction)

Question 20

Where is beta 2 receptor located?

Answer 20

It is located at non-synaptic sites

Question 21

Effects of beta 2 receptor

Answer 21

1) Bronchial smooth muscle relaxes (bronchiodilatation)
2) Some vascular smooth muscle relaxes (but vasodilation in skeletal muscle, coronary and hepatic arterioles, some veins)
3) liver (glycogen mobilisation)

Question 22

Effects of alpha 2 receptor

Answer 22

1) Vascular smooth muscle contracts (vasoconstriction, reduced blood flow, increased blood pressure)
2) Longitudinal muscle of GI tract relaxes, anal sphincter contracts (reduced motility, constipation)
3) eye radical contraction (pupil dilates)
4) Salivary glands - secretion of thick saliva
5) Liver - glycogen mobilisation
6) Vas deferens contracts - ejaculation