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Hemicholinium
Potent competitive inhibitor of choline reuptake --> decrease in ACh synthesis --> synaptic fatigue
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alpha-Latrotoxin
Black Widow Spider Toxin: causes excessive release of ACh
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Botulinum Toxin A-G
- From Clostridium botulinum; inhibits release of ACh from nerve terminal (as does tetanus toxin).
- "Botox" is used to treat focal dystonias and spasms associated with cerebral palsy, hyperhydrosis, wrinkles, etc.
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Heavy Metals
- Lead, cadmium, etc.
- Potent antagonists of calcium entry into nerve terminal and inhibits ACh release (only a submicromolar concentration is needed to cause this)
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Neostigmine, sucinylcholine, physostigmine
inhibit AChE to increase [ACh] in cleft; for glaucoma and myasthenia gravis.
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Curare
- binds with high affinity to nicotinic AChR, blocking bindingn of ACh. Leads to paralysis.
- Use curare or curare-like drugs to induce muscle relaxation during abdominal surgery.
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Alpha-bungarotoxin
cobra snake venom; binds irreversibly to AChR --> paralysis
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Organophosphates (insecticides, nerve gases)
Irreversible inactivation of AChE
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Nicotine affects what kind of muscle?
- Skeletal - causes contraction
- Crude extract from tobacco, containing nicotine
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Muscarine affects what kind of muscle?
- Smooth - causes contraction or glandular secretion
- Crude extract from the Amanita mushroom containing muscarine
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Responses to nicotine can be blocked by ______ but not ________.
By tubocurarine, but not by atropine
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Responses to muscarine can be blocked by ______ but not ________.
By atropine, but not tubocurarine.
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