Session 10 Flashcards
What neurotransmitter do pre-ganglionic neurones use in the Sympathetic branch of the ANS?
Acetylcholine
What neurotransmitter do pre-ganglionic neurones use in the Parasynpathetic branch of the ANS?
Acetylcholine
What neurotransmitter do post-ganglionic neurones use in the Sympathetic branch of the ANS?
Noradrenaline
What neurotransmitter do post-ganglionic neurones use in the Parasympathetic branch of the ANS?
Acetylcholine
What receptors receive acetylcholine in the ANS?
Nicotinic
What is Acetylcholine synthesised from?
Choline using the choline acetyltransferase enzyme
What are NANC transmitters?
Non Adrenergic, Non Cholinergic transmitters.
When are NANC transmitters released?
They can be co released with Noradrenaline/Acetylcholine
What are some examples of NANC transmitters?
NO
ATP
5HT
What are the 2 termination mechanisms of noradrenaline?
Uptake 1
Uptake 2
What is Uptake 1?
Noradrenaline is terminated by reuptake into the presynaptic terminal by a Na+ dependent transporter
What is Uptake 2?
Noradrenaline is not recaptured by Uptake 1 and is taken up by a lower affinity non neuronal mechanism
What degrades Acetylcholine?
Cholinesterase in the synaptic cleft
If Acetylcholine is not broken down by Cholinesterase, where can it go?
Into synaptic vesicles
What breaks down cytoplasmic noradrenaline?
Monoamine Oxide
What is Noradrenaline synthesised from?
Tyrosine in the nerve terminal
What are the 4 main classes of drugs which act on the ANS?
Nicotinic Cholinoceptor Antagonists
Muscarinic Cholinoceptor Agonists
Muscarinic Cholinoceptor Antagonist
Cholinesterase Inhibitors
What type of drug is Pilocarpine?
Muscarinic Cholinoceptor Agonist
What is Pilocarpine used for clinically?
Treatment of Glucomas
What type of dug is Tubocurarine?
Nicotinic Cholinoceptor Antagonist used for muscle paralysis
What type of drug can be used to treat Myasthenia Gravis?
Cholinesterase Inhibitors
What Muscarinic Cholinoceptor Antagonist can be used for pupil dilation?
Tropicamide
What is alpha Methyl-tyrosine?
A drug that completely blocks tyrosine hydroxylase so synthesis of noradrenaline is stopped
When is alpha Methyl-tyrosine used clinically?
In Pheochromocytoma
What is alpha-Methyl-DOPA?
It inhibits voltage operated calcium channels
How does alpha Methyl DOPA inhibit VOCC?
Acts like noradrenaline, but poorly metabolised so accumulates in synaptic vesicles.
When these are released it acts on pre synaptic alpha 2 receptors which inhibit VOCC and reduce Ca2+mediated release
What is CarbiDOPA?
Inhibits DOPA decarbocylase, but ONLY in the peripheral nervous system as it cannot cross the BBB
How do Adrenergic Blocking Drugs work?
Reducing impulse conduction
Reduces Ca2+ mediated exocytosis
Reduces repletion of Noradrenaline
How do Indirectly-acting Sympathomimetic Agents (IASAs) work?
They are taken into vesicles by Uptake 1.
The displaced Noradrenaline will leak into the synaptic cleft.
This can inhibit Noradrenaline degrading enzyme - MAO
Give an example of Uptake 1 Inhibitors?
Tricyclic antidepressants. Exert action centrally, possible peripheral actions are side effects
