PHA3801 Lecture Notes - Lecture 20: Carbamate, Carbachol, Edrophonium
24 Jul 2018
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Inhibits metabolism of ach ach levels inc, effects of receptor stimulation inc. Parasympathetic nerves innervate constrictor muscles (iris) + ciliary muscle (adjusts lens curvature). Constrict pupil in response to inc light. Open angle glaucoma: inc intra-ocular pressure (optic nerve may be damaged), drainage of aqueous humour is impaired when pupil dilated (folding of iris tissue blocks drainage angle), cholinergic agonists constrict pupil. Urinary retention, paralytic ileus, assessment of pancreatic function. Acetylcholinesterase has anionic site (-ve) and esteratic site (+ve). Inhibitors may bind to enzyme prevent ach binding prevent breakdown inc ach levels. Cholinesterases: catalyse the hydrolysis of ach (ach-est and pseudocholinesterase). C-i"s inhibit the catalytic activity of c enzymes ach accumulates. Edrophonium combines reversibly w the anionic site of ach-est effective only a few mins. Can be used to diagnose skeletal muscle disease myasthenia gravis (a-i disease affecting nmj nicotinic receptors blocked by antibodies). Physpstogmine + neostigmine interact w both the anionic and esteratic site of ach-est.
