Adrenergic Agonist: Dopamine, Reserpine, Norepinephrine, Guanethidine, Phenylephrine, Ephedrine, Tricyclic Antidepressants, Tca, Cocaine, Imipramine, Amphetamine, Tyramine, Metaraminol, Clonidine, Epinephrine, Isoproterenol, Metaproterenol, Terbutaline mnemonic

Adrenergic Agonist Overview

Normally the neuron converts tyrosine DOPA Dopamine [dope mine] in cytoplasm
Dopamine is packaged into vesicles
- Reserpine [research pine] blocks this process
Dopamine is converted to norepinephrine [nose pine rhino] inside the vesicle
MAO degrades dopamine and norepinephrine in cytosol [General Mao Zedong (Chinese ruler) sipping the contents of vesicles]
Norepinephrine is released from vesicles into synaptic cleft upon when the neuron is stimulated
- Guanethidine [iguana and him dine] blocks the release of vesicles
Once in the synaptic cleft, norepinephrine stimulates mainly alpha-1 and alpha-2 receptors. Excess is degraded by COMT enzyme [comet] or is taken up by the presynaptic neuron [rhino turns around toward the bouton]
Synthetic norepinephrine derivatives, phenylephrine [ phenyl rhino] and ephedrine [fed rhino] are resistant to degradation by COMT [comet bouncing & dropping]
Re-uptake is blocked by Tricyclic antidepressants (TCA's) [compound with 3 rings], Cocaine [cock aim], imipramine [imitating mine]
The vesicles can be artificially stimulated to be released by amphetamine [amplifier mine] and tyramine [tyrannosaurus mine spilling the vesicles]
Metaraminol [met ram pole] also can cause spilling of the vesicles, in addition to direct action on adrenergic receptors [pole spilling blue vesicles and also energizing postsynaptic membrane]
[Alpha and Beta receptors are represented by a clover symbol, where alpha 's are on the top, and beta's are on the bottom]
Alpha-1 receptors are in vasculature, and their stimulation results in constriction [alpha symbol looks like the ends are being pulled to constrict the circular part]
Norepinephrine stimulates predominantly alpha receptors, resulting in vasoconstriction with elevation of both systolic and diastolic blood pressure [blood pressure indicator]
Alpha-2 receptors are inhibitory receptors on presynaptic neuron. Their stimulation causes lowering of intracellular cAMP [clover alpha-2 lowers a pole onto a cAMPing tent]
- Clonidine [Clones dine] stimulates alpha-2 receptors
Beta-1 receptors are located in the heart and uterus, stimulating contraction of these organs [heart and uterus] [must stimulate the heart before stimulating the uterus]
Beta-2 receptors are responsible for bronchodilatation and arterial dilatation in skeletal muscle [dilating pipe with beta-2 symbol]
Epinephrine [orange pine rhino] primarily stimulates beta-1 receptors. This results in increased systolic pressure and can promote arrhythmias [tickling the shaking heart]
Isoproterenol ["Is a protest" renal] stimulates beta-1 and beta-2 receptors. [bottom part of clover]

Strongest beta selectivity (more so than epinephrine)
Resistant to COMT [comet dropping]
Stimulates the heart (beta-1) and dilates bronchi (beta-2) [heart & thick trachea]

Metaproterenol ["Me tap" protesting renol with red lung in beta-2 position] dilates bronchi [dilated trachea] and is used to treat asthma
Terbutaline [terrier but alien] is another beta-2 agonist [terrier sniffing the beta-2 receptor]
- bronchodilator used to treat asthma
- Reduces uterine contractions [finger plugging the uterus]

Visual Mnemonic - Adrenergic Agonist: Dopamine, Reserpine, Norepinephrine, Guanethidine, Phenylephrine, Ephedrine, Tricyclic Antidepressants, Tca, Cocaine, Imipramine, Amphetamine, Tyramine, Metaraminol, Clonidine, Epinephrine, Isoproterenol, Metaproterenol, Terbutaline
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