Adrenergic receptors

Question 1

How does adrenaline increase blood pressure?

Answer 1

leads to contraction of vascular smooth muscle

Question 2

Ergots explained

Answer 2

group of similar alkaloids that appear to be antagonists for adrenergic receptors

include ergotamine- used to treat migraines- and ergometrine- uterine smooth muscle contraction for partruition

ergot poisoning- St Anthony’s Fire- caused by eating infected grain where fungus secreting ergots grew

suffer from sharp burning sensations and blackened limb- gangrene

Question 3

difference between NA and A

Answer 3

A has a methyl group attached to the nitrogen, whereas NA has hydrogen

Question 4

4 types of adrenergic receptor

Answer 4

Alpha 1 & 2, beta 1 & 2

Question 5

rank order of agonist potency at alpha

Answer 5

smooth muscle contraction- aLPHA

noradrenaline > isoprenaline

Question 6

rank order of agonist potency at beta

Answer 6

smooth muscle relaxation

isoprenaline> adrenaline&raquo_space; noradrenaline

Question 7

Evidence to suggest different receptors with different responses

Answer 7

Isolated different smooth muscle preparations and added agonists. The muscles either contracted or relaxed when different preparations were added

Question 8

What is noradrenaline most likely to stimulate?

Answer 8

alpha receptors

Question 9

what is adrenaline most linked to stimulate?

Answer 9

Alpha, but also slightly beta

Question 10

what is isoprenaline most linked to stimulate?

Answer 10

beta

Question 11

Bulkier agonists prioritise which receptors?

Answer 11

beta

the more bulky, the more likely to stimulate beta

Question 12

Where are alpha 1 receptors found? + effect

Answer 12

blood vessels, heart and skeletal. Smooth muscle constriction

bronchi- smooth muscle constriction

G.I tract - relaxation, decrease motility

liver- glycogenolysis and gluconeogenesis

eye- pupil dilation

Question 13

where are alpha 2 receptors found? + effect

Answer 13

blood vessels- however a lot less than A1

bronchi

Question 14

where are beta 1 receptors found? + effect

Answer 14

heart- decreased heart rate and force

blood vessels relaxation

G.1. tract

Question 15

where are beta 2 receptors found? + effect

Answer 15

heart- but mainly beta 1

bronchi relaxation

liver

skeletal muscle- tremor and thermogenesis

Question 16

where are beta 3 receptors found? + effect

Answer 16

skeletal muscle

adipose tissue- lipolysis and thermogenesis

Question 17

2 types of ways agonists can act + examples

Answer 17

directly- adrenaline binds directly to receptor

indirectly- tyramine, ephedrine and amphetamine competitively taken up into vesicles

Question 18

What is used to treat an anaphylactic shock?

Answer 18

epipen containing adrenaline

leads to rapid vasoconstriction- alpha 1 stimulated

leads to rapid bronchiole dilation- b1 stimulated

causes a reverse bronchospasm

however can lead to stimulation of the heart, leading to acute cardiac failure

Question 19

widespread action of adrenaline

Answer 19

decreased total peripheral resistance

slight increased heart rate

slight increased systolic blood pressure

Question 20

widespread action of noradrenaline

Answer 20

huge increase in systolic and diastolic pressure

decrease in heart rate

large increase in total peripheral resistance

Question 21

widespread action of isoprenaline

Answer 21

decrease in systolic and diastolic blood pressure

huge increase in heart rate

decrease in total peripheral resistance

Question 22

How do alpha-1 receptors work?

Answer 22

GCPR- Gq- agonist binds, activates phospholipase C, leading to an increase in iP3 and DAG messengers

Question 23

3 selective agonists of alpha 1 + uses

Answer 23

phenylephrine- counters acute hypotension, treats nasal congestion due to vasoconstrictive effect

xylometazoline- nasal decongestion, can lead to necrosis of tissue due to intense vasoconstriction

metaramino- acute hypotension

Question 24

How do alpha 2 receptors work?

Answer 24

GPCR- Gi/o - inhibit adenylyl cyclase, leading to a decrease concentration of cAMP concentrations, decrease PKA, less voltage gated calcium channel stimulation

Question 25

agonists of alpha 2 + uses

Answer 25

clonidine- anti-hypertensive, central and peripheral actions xylazine- sedative effects via CNS

Question 26

how do beta 1 & 2 receptors work?

Answer 26

GPCR- Gs and Gq- activate adenylate cyclase, increase cAMP concentrations, increases PKA, increases voltage gated calcium channel openings cAMP activates funny current, HCN, channels B2- PKA phosphorylates phospholamban, removing inhibition of SERCA, increased ate of reabsorption of calcium, leads to smooth muscle relaxation

Question 27

agonists of beta 1 + uses

Answer 27

increases rate and force of heart contraction, relax GI smooth muscle dobutamine- some uses cardiogenic shock, inotropic support in infarction Isoprenaline- cardiac stimulant, non selectivity limits use

Question 28

agonists of beta 2 + uses

Answer 28

salbutamol, terbutaline- short acting bronchodilators used for asthma treatments

Question 29

How does ergot work?

Answer 29

partial agonist- stimulate then block bind to the adrenergic receptors and act initially as an agonist, increasing the BP This is followed by a decrease in BP, as they prevent other agonists from binding

Question 30

beta blockers explained

Answer 30

A class of medications that are predominantly used to manage abnormal heart rhythms and protect the heart against a second heart attack competitive antagonists on adrenergic beta receptors of the sympathetic nervous system

Question 31

example of one specific beta blocker

Answer 31

atenolol, used primarily to treat high blood pressure and heart-associated chest pain works by blocking beta 1 adrenergic receptors in the heart, thus decreasing the heart rate and workload as it is specific to B1, less likely to cause bronchoconstriction