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24 Cards in this Set
- Front
- Back
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Tyrosine -> Dopa
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goes to axoplams of symp nerve endings and is converted to dopa via TH
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Dopa -> Dopamine
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dopa is decarboxylated to dopamine (DA) via L-aromatic amino acid decarboxylase
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Dopamine -> Norepinephrine
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– dopamine goes into adrenergic storage vesicles
- converted to NE via dopamine B-hydroxylase (DBH) |
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Norepinephrine -> Epinephrine
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in neurons in the brain, NE -> EPI via PNMT
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NE storage
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stored in vesicles w/ ATP and DBH in nerve terminals
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Cat storage in adrenal gland
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in adrenal medulla is in chromaffin granules (larger)
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Cat release
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- AP reaches post symp nerve
– released via Ca2+ dependent, exocytosis |
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release of cats from adrenal gland
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- Activation of pre nerves to the adrenal medulla
- activation of a nicotinic R on chromaffin cells - that leads to release of EPI from chromaffin granules by Ca2+-dependent exocytosis - EPI into blood and distributed as hormone |
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Catechol-O-methyltransferase (COMT)
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converts EPI to inactive metanephrine
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Entacapone
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inhibits COMT – it and levodopa treat Parkinson’s disease
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Monoamine oxidase (MAO)
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- converts catecholamines to aldehydes, which are reduced to alcohols or oxidized to acids (both inactive)
- in symp endings to regulate cats - in liver and kidney to metabolize cats |
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MAO inhibitors
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- tranylcypromine and isocarboxazid
- used as antidepressants |
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Neuronal uptake (Uptake I)
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- A transport protein on the PM of the symp nerve terminal transports NE from the synaptic space into the symp nerve ending
- against gradient, requires ATP |
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cocaine
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inhibits neuronal uptake
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imipramine
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- tricyclic antidepressant
- inhibits neuronal uptake |
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Non-Neuronal Uptake (Uptake II)
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- different selectivity for binding and transport of amines
- unimportant for termination of symp signals - but may play a role in regulating blood levels of EPI |
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Vesicular Uptake
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- transports dopamine (and NE) into storage vesicles via active amine pump
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reserpine
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- selectively and irreversibly inhibits vesicular uptake
- depletes intraneuronal NE in brain and periphery (rapid inactivation by MAO) |
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Tyramine
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- a phenylethylamines that can be taken into storage vesicles and displaces NE
- NE is released non-exocytotically and causes an acute sympathomimetic effect - found in certain foods |
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amphetamine
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- a phenylethylamines that can be taken into storage vesicles and displaces NE
- NE is released non-exocytotically and causes an acute sympathomimetic effect |
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Pts treated w/ nonselective MAO inhibitors and Tyramine
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- tryamine in food is normally broken up by MAO in the liver and gut before it gets to the bloodstream
- may develop hypertensive crises due to ingestion of foods high in tyramine |
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dopamine generic names
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(Dopastat, Intropin)
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norepinephrine generic names
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(Levophed)
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epinephrine generic names
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(Adrenalin, Bronchaid, Primitine)
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