PCOL2605 Lecture Notes - Lecture 7: Myasthenia Gravis, Muscarinic Acetylcholine Receptor, Postganglionic Nerve Fibers
23 Oct 2018
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Document Summary
Acetylcholine acts at nicotinic and muscarinic receptors. All nicotinic receptors are composed of 5 subunits and are all ligand gated ion channels. All organs innervated by parasympathetic postganglionic nerve fibres (e. g. heart, eye, salivary glands, gi and respiratory smooth muscle) Sweat glands (innervated with sympathetic post ganglionic nerve fibres which release acetylcholine) M3 (smooth muscle contraction in gi and respiratory tract, pupillary constriction in eye) Reversibly inhibit the enzyme acetylcholinesterase, increase the concentration of acetylcholine in the synapse and produce cholinergic effects. Neostigmine acts peripherally and is used in the treatment of myasthenia gravis and to reverse the effects of non-depolarising neuromuscular blocking drugs. Donepezil acts centrally and is used i(cid:374) the treat(cid:373)e(cid:374)t of alzhei(cid:373)er"s disease. Very few of the drugs which exert an agonist action on acetylcholine nicotinic receptors are used therapeutically: Varenicline is used as an aid to smoking cessation. Partial agonist at central nicotinic acetylcholine receptors.
