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33 Cards in this Set
- Front
- Back
- 3rd side (hint)
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ANS - myelinated vs. non-myelinated?
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Preganglionic fibers are myelinated and postganglionic fibers are non-myelinated.
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What is the rate-limiting step in cholinergic neurotransmission?
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Uptake of choline into nerve terminal.
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What effect does the botulinum toxin have on release of ACh?
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Decreases
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What effect does hemicholinium have on the synthesis of ACh?
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Inhibits it.
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How does the botulinum toxin inhibit ACh release?
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By degrading proteins involved in the synaptic release of ACh. This prevents the vesicles from attaching to the membrane.
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Which drugs can target single types of cholinoceptors?
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Haha. Trick question. No drug! Can only target ALL muscarinic receptors.
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Differences between muscarinic and nicotinic receptors structure?
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Muscarinic = 7 transmembrane; g-protein coupled
Nicotinic = ion channel; pentamer; |
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Do nicotinic acetylcholine receptors make use of second messengers?
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Nope. They are directly linked to an ion channel.
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ACh stimulates M3 receptor on the endothelium membrane, resulting in release of NO, causing _____.
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vasorelaxation
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ACh stimulates M3 receptor on vascular smooth muscle membrane, causing _____.
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vasoconstriction
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Denuding the blood vessel of its endothelium will unmask vasocontraction, which will be _____.
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augmented
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Administration of muscarinic agonists mimics the actions of _____ stimulation.
What are the characteristics of the response dependent upon? |
parasympathetic
1. susceptibility to acetylcholinesterase 2. selectivity for the muscarinic receptor |
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What are the four direct-acting muscarinic receptor agonists?
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choline esters:
-carbacol -bethanecol alkaloids -pilocarpine -muscarine |
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What is the direct-acting nicotinic receptor agonist?
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Nicotine
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Cholinergic stimulants can be direct-acting receptor agonists, or indirect-acting _____ inhibitors.
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cholinesterase
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What are the six indirect-acting cholinergic stimulants?
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Physostigmine
Neostigmine Edrophonium Malathion DFP Nerve gas |
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Which of the cholinesterase inhibitors, are reversible?
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Physostigmine
Neostigmine Edrophonium |
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Irreversible?
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Malathion
DFP Nerve gas |
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Two indirect acting muscarinic agonists?
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Cisapride
Metoclopramide |
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Cisapride is a ____ agonist.
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5-HT4
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Where are 5-HT4 receptors found?
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Myenteric plexus of the intestine.
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Ultimate effect of cisapride?
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It sensitizes the smooth muscle (in GI) to the actions of ACh.
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Metoclopramide is a ____ agonist and a _____ antagonist
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5-HT4
dopamine |
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Metoclopramide inhibits dopamine. What effect does this have?
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Dopamine has an inhibitory effect in the enteric nervous system. So, metoclopramide inhibits the inhibition.
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In the heart and CNS, effects of nicotine are primarily _____ and dramatic _____ results from injection of nicotine IV.
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sympathetic
hypertension |
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Adverse reactions of cholinergics:
muscarinic excess |
Salivation, seizure
Lacrimation Urination GI distress: diarrhea, vomiting Bronchoconstriction Abdominal cramps Miosis |
SLUGBAM
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Adverse reactions of cholinergics:
nicotinic excess |
Mydriasis
Tachycardia Weakness (muscle paralysis) Th = hyperThermia Fasciculations |
MTWThF
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Acetyl choline esterase (AChE)
Each molecule is made of four units. Each unit has an active center. What does this active center consist of? |
1. Anionic subsite - negatively charged. It attracts choline by ELECTROSTATIC forces.
2. Esteratic subsite - serine hydroxyl group of the enzyme forms a COVALENT bond with the acetate of ACh. |
electrostatic and covalent
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What is neostigmine?
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A reversible cholinesterase inhibitor. By interfering with the breakdown of acetylcholine, neostigmine indirectly stimulates both nicotinic and muscarinic receptors.
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Which is better absorbed and longer lasting: neostigmine or pyridostigmine?
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Pyridostigmine
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Primary effect of anticholinesterases?
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Potentiation of effects of ACh at cholineric nerve endings.
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Effects of indirect acting cholinergic stimulants will be similar to effects of direct acting agonists, but will differ in two ways:
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1. CNS effects - effects only with lipid soluble anti-ChEs
2. Nicotinic effects |
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What are the major therapeutic uses of cholinergic receptor stimulants?
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Eyes - glaucoma
GIT - postoperative muscle weakness (atony) NMJ - myasthenia gravis Antimuscarinic drug intoxication - atropine, eg Alzheimer's |
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