Autonomic & NMJ Pharmacology Flashcards
(32 cards)
What are the two types of cholinergic receptors?
- Nicotinic (selectively activated by nicotine) - ionotropic (ligand gated) with an integral ion channel
- Muscarinic (selectively activated by muscarine) - split into M1/2/3 based on what G protein they’re coupled to and therefore 2nd messenger signals they produce
What are the types of adrenergic receptors?
All metabotropic are are split into a1/2/3 and B1/2/3/4
Steps in synaptic transmission
- Transmitter synthesis and packaged into vesicles
- AP activates voltage gated Ca2+ channels
- Triggers Ca2+ dependent exocytosis of pre-packaged vesicles of transmitter
- Binds to iono/metaboltropic receptors of postsynaptic membrane
- Also binds to presynaptic autoreceptors which inhibit further transmitter release
- Transmitter inactivated and uptake into neurones and glia
- Transmitter metabolised with cells
What does hemicholinium do at the NMJ?
Inhibits choline transporter
What does Black widow spider venom do at the NMJ?
Block voltage gates Ca2+ channels
What does botulinum toxin at the NMJ?
Block vesicle fusion
What does d-tubacurarine do at the NMJ?
It is a non-depolarising nicotinic receptor blocker
What does succinylcholine do at the NMJ?
It is a depolarising nicotinic receptor blocker
What does eserine do at the NMJ?
Block acetylcholinesterase - inhibit ACh break down so it remains in the synaptic cleft
What are non-depolarising and depolarising blockers used for?
Paralysis during:
- Surgery
- Electroconvulsive therapy
- Controlling spasms in tetanus
What is botox used for?
Treating muscle spasm and cosmetic procedures
What is anticholinesterase used for?
- Treating myasthenic syndromes
- Reversing action of non-depolarising blockers
- Countering botulinum poisoning
Potential sites of action for drugs on the postganglionic parasympathetic transmission
- Muscarinic receptor antagonists
- Muscarinic receptor agonists - mimic effects
Action on Atropine on postganglionic parasympathetic transmission
Muscarinic receptor antagonist
Pilocarpine
agonist of muscarinic receptors
What are muscarinic receptor antagonists used for?
Block effects of parasympathetic system
What are muscarinic receptor agonists used for?
Mimic effects of parasympathetic system
Problem associated with postganglionic parasympathetic transmission drugs
Not many specific agonist or antagonists available so the drug mimics or blocks all effect caused of para sympathetic NS unless you can deliver drug straight to site of action (inhalation to lungs, eyedrops)
What can muscarinic agonists treat?
Glaucoma (raised intraoccqular pressure) - agonists contract ciliary muscle and contract the sphincter muscle of the pupil which opens trabecular network and increase drainage of the aqueous humour - MITOTIC DRUGS
What is miosis?
Making pupil smaller
What does carbidopa do in the postgang sympathetic transmission?
Blocks the enzymes that produce NA
What does reserpine do in the postgang sympathetic transmission?
Block the transporter that fills the vesicles with NA
What does methyldopa do in the postgang sympathetic transmission?
‘False’ transmitter - packaged and released as NA but cannot activate adrenergic receptors
What does amphetamine do in the postgang sympathetic transmission?
Stimulate NA release - sympathomimetic amines
