Chol/Adrengeric Responses Flashcards
Interference with synthesis of neurotransmitter
Cholinergic: choline acetyl transferase inhibitors
Effect: depletion of ACh
Adrenergic: A-methyl tyrosine inhibits tyrosine hydroxylase
Effect: depletion of NE
Overall Action: SYMPATHOLYTIC
Metabolic transformation by same pathway as precursor of neurotransmitter (I.e. fool body into thinking its making catecholamine when its not)
Adrenergic: methyldopa
Effects: displacement of NE by methyl-NE, which is a2 agonist that reduces sympathetic outflow from CNS
Overall action: SYMPATHOLYTIC
Blockade of transport system at nerve terminal membrane/blockade of NE re-uptake
Cholinergic: hemicholinium
Effect: block choline uptake with consequent depletion of ACh
Adrenergic: cocaine, imipramine
Effect: Accumulation of NE at receptors but NE not being reused so could end up being SYMPATHOLYTIC
Overall Action: SYMPATHOMIMMETIC
Block add of transport system of storage vesicle
Cholinergic: Vesamicol
Effect: block ACh storage
Adrenergic: Reserpine—>depletes vesicles
Effect: destruction of NE by MAO and depletion from adrenergic terminals (no longer protected by vesicle)
Overall action: SYMPATHOLYTIC
Promotion of exocytosis or displacement of transmitter from axonal terminal
I.E. NE indirectly release from nerve
Cholinergic: latrotoxins
Effect: Cholinomimetic followed by anti cholinergic
Adrenergic: Amphetamines/tyramines/Ephedrine
Effect: adrenomimetic
Overall Action: SYMPATHOMIMMETIC
Prevention of release of neurotransmitter
I.e. presynaptic negative feedback
Cholinergic: botulism
Effect: Anticholinergic
Adrenergic: Clonidine, precedex
Effect: Antiadrenergic
Overall Action: SYMPATHOLYTIC
Mimicry of transmitter at postjunctional sites
I.e. classic agonist. Give drug and directly stimulate receptor
Cholinergic: methacholine, bethanachol
Effect: Cholinomimetic
Adrenergic: Nicotine, phenylepherine, dobutamine, albuterol, isoproterenol
Overall Effect: SYMPATHOMIMMETIC
Blockade of postsynaptic receptors
Cholinergic: Atropine (muscarinic blockade), atracurium (NM blockade)
Adrenergic: A or BB
Overall Action: SYMPATHOLYTIC
Inhibition of enzymatic breakdown of transmitter
Cholinergic: AChE inhibitors (edrophonium/neostigmine)
Effect: Parasympathomimetic
Adrenergic: MAO-Is, MAO-B inhibitor, COMT inhibitor
Effect: SYMPATHOMIMETIC
Interference with second messenger system
Adrenergic: PDE-III inhibitor (milrinone)—> prevent breakdown of cAMP
Effect: Inotrope
Overall Action: Sympathomimetic
Normal State of Catecholamine Action
AP comes down nerve causing NE release from vesicles —> NE attaches to post-synaptic receptors —> sympathetic effect —> some NE metabolized by COMT in synapse, some taken back up into presynaptic neuron —> feedback and stored in vesicle —> mitochondrial MAO can metabolize cytoplasmic NE in order to prevent NE from being taken back up into vesicle
