drugs acting in the Sympathetic system Flashcards
Name 6 things the sympathetic nervous system does
think HR, bronchi and mucus, sweating, gut muscles and secretion, adrenaline and detrusor muscle
- increased heart rate
- bronchodilation and inhibiton of mucus secretion
- increased sweating
- Decreased motility of gut muscles and inhibition of secretion
- release of adrenaline
- relaxation of detrusor muscle contraction of sphincter decreased micturition
What neurotransmitter is produced from the postganglionic neurons and effects adrenergic receptors in the sympathetic nervous system
noradrenaline
What neurotransmitter is produced from the preganglionic neuron and effects nicotinic acetylcholine receptors in the Sympathetic nervous system
ACh
what receptors are does Ach from the preganglionic neurone bind to to allow the eventual release of Noradrenaline
nicotinic acetylcholine receptors
What are the 2 outlier target organs that are stimulated by ACh rather than adrenaline/noradrenaline
- adrenal medulla
- sweat glands
What is the main neurotransmitter that works in the airways alongside noradrenaline
adrenaline
What is the relative potency ranking list in a-adrenergic receptors
adrenaline > noradrenaline > isoprenaline
What are the 2 two subtypes of a-adrenergic receptors
- a1-adrenergic receptors
- a2-adrenergic receptors
What is the relative potency in B-adrenergic receptors
isoprenaline > adrenaline > noradrenaline
What are the 2 subtypes of B-adrenergic receptors and state if adrenaline or noradrenaline is more potent at each receptor subtype
- B1 adrenergic receptors (adrenaline and noradrenaline potency is equal)
- B2 adrenergic receptors ( adrenaline is more potent then noradrenaline )
where are B2 receptors
- lungs
- blood vessels
where are B1 receptors found?
- heart
- gut
What G protein are B1 receptors couple to in the heart and what does this do in heart
- Gs G protein
- increase heart rate and force of contraction of cardiac muscle.
Via what molecule do Gs G proteins signal
cAMP
Outline how adrenaline/noradrenaline increases heart rate
- Adrenaline/noradrenaline binds to B1 receptor
- a-GTP subunit of Gs protein binds to adenylyl cyclase, converting ATP to cAMP
- cAMP binds to sodium ion channels, opening them and allowing influx of sodium ions
- depolarizes cardiac cell membrane, increasing HR
Outline how adrenaline/noradrenaline increase force of contraction
- Adrenaline/noradrenaline binds to B1 receptor
- a-GTP subunit of Gs protein binds to adenylyl cyclase, converting ATP to cAMP
- cAMP activates Protein Kinase A (PKA)
- PKA binds to calcium ion channels, opening them and allowing influx of Ca2+
- this depolarizes cardiac cell membrane, increasing force of contraction
Outline how adrenaline/noradrenaline causes bronchodilation
- Adrenaline/noradrenaline binds to B2 receptor
- a-GTP subunit of Gs protein binds to adenylyl cyclase, converting ATP to cAMP
- cAMP activates PKA
- PKA phosphorylates myosin light chain kinase, which effects the myosin muscle system, causing relaxation of smooth muscle
what 2 reasons does salbutamol work longer and thus a better alternative to adrenaline in treating asthma with inhalers
- more resistant to metabolism by COMT on the HO- side of the molecule
- more resistant to metabolism by MAO on the CH3 end
What drug is better for treating asthma than salbutamol and how long does it last
- salmeterol
- 12 hours
How is Noradrenaline (NA) reuptaken into the postganglionic neuron
Noradrenaline transporter (called NET)
Name 2 uptake inhibitors of noradrenaline
- cocaine
- amphetamine
What are unwanted cardiovascular effects of cocaine and amphetamine
- In Heart: increased rate and force of contraction
– In blood vessels: blood vessels constricting
- in Kidneys: release of renin, increasing fluid volume.
this is all due to increase noradrenaline in the synaptic cleft
What are unwanted urinary bladder effects of cocaine and amphetamine
relaxtion of detrustor muscle and contraction of sphincter muscles leading to urinary retention (cant go to the toilet) due to increased Noradrenaline in the cleft.