Adrenergics I Flashcards by Justin Muego

Dopamine is important in the regulation of:

Sodium excretion and renal function

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Chemical structure of the catechol nucleus:

3,4 dihydroxyl benzene ring

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Mechanisms of Indirect agonism:

1) Displacement and release of stored catecholamines
2) Inhibition of catecholamine reuptake
3) Blockade of metabolic enzymes

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Differences in between non-catecholamines and catecholamines:

Less efficacious
Lipid soluble, penetrate the BBB (no OH)
Well absorbed orally
Longer duration of action (resistant to COMT)

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MAO degradation of neurotransmitters occurs in the:

nerve terminal cytoplasm

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MAO resistant neurotransmitter enter the nerve via this transporter:

Vesicular monoamine transporter (VMAT)

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NE in the extra-synaptic space and circulating epinephrine are metabolized by:

COMT (Extraneuronal uptake)

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The principal metabolite of norepinephrine in the brain:

3-hydroxy-4-methoxyphenyl glycol

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The end-stage catecholamine metabolite ___ is excreted via the ____:

Vanilyllmandelic acid (VMA); urine

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Stimulation of these alpha receptors leads to vasoconstriction:

Post-junctional Alpha-1 and Alpha-2

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Stimulation of these alpha receptors leads to vasodilation:

Pre-junctional Alpha receptors

Endothelial Alpha-2

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Beta-2 stimulation leads to ___ of muscle due to phosphorylation of ____:

relaxation; myosin light chain kinase (MLCK)

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The dopamine receptors that stimulate adenylyl cyclase:

D1 and D5

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Dopamine receptors inhibition adenylyl cyclase:

D2 (hyperpolarization)

D3 and D4

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The most powerful stimulant of liver glycolysis:

Epinephrine

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The most powerful stimulant of muscle glycolysis:

Isoproterenol

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α1 > α2&raquo_space;> β

Phenylephrine

Methoxamine

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α2 > α1 &raquo_space;> β

clonidine and methyldopa:

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α1 = α2; β1&raquo_space;> β2

Norepinephrine

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α1 = α2; β1 = β2

epinephrine

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β1 > β2&raquo_space;> α

Dobutamine

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β1 = β2&raquo_space;> α

Isoproterenol

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β2&raquo_space; β1&raquo_space;> α

terbutaline and albuterol

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D1 = D2&raquo_space; β&raquo_space; α

Dopamine

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D1 >> D2

Fenoldopam

Best choice for cardiogenic shock:

Dopamine

Tachyphylaxis desensitization is exemplified by:

indirectly acting sympathomimetic drugs

Two categories of GPCR mediated desensitization:

Homologous (arrestin) | Heterologous (phosphorylation)

The parent compound of catecholamines, ___, is composed of:

phenylethylamine; benzene ring + ethylamine with terminal amino group

Dopamine structure is a catechol nucleus + ___:

ethylamine

Norepinephrine structure is dopamine + ___:

OH at β-carbon

Epinephrine structure is norepinephrine + ___:

methyl group at amino terminal

Isoproterenol structure is epinephrine + ___:

2 methyl groups at methyl substitution

in catecholamines, the larger the ___ substitution, the greater the affinity to __ receptors:

alkyl; β receptors

Phenylephrine is epinephrine structure without the ____:

1 OH group on benzene ring

Ephedrine has these differences from epinephrine structure:

less 2 OH groups | Methyl-substitution on the α-carbon

Absence of this group makes non-catecholamines resistant to COMT:

OH groups

Presence of this group makes non-catecholamines resistant to MAO:

α-carbon methyl group

As size of amino group substituents increases:

Increased β receptor activity | Decreased α receptor activity

Groups with substitution to the α-carbon block ___ metabolism and act ___:

MAO; indirectly

Groups with substitution to the β-carbon act ___ and may be important in the ___:

Directly; storage of transmitters in neural vesicles

Tissues with α1 receptors:

Most vascular smooth muscle Pupillary dilator muscle Pilomotor smooth muscle Heart

Tissues with α2 receptors:

``` Postsynaptic CNS adrenoreceptors Platelets Adrenergic and cholinergic nerve terminals Vascular smooth muscle Fat cells JG cells ```

Tissues with β2 receptors:

Respiratory, uterine and vascular smooth muscle Skeletal muscle Human liver

Use of pure α agonists lead to this cardiovascular reflex:

Reflex bradycardia

Receptors for decreased insulin secretion:

α2

Receptors for increased insulin secretion:

These receptors stimulate renin secretion:

β1

These receptors inhibit renin secretion:

α2

Adrenoreceptors modulate the secretion of:

PTH Calcitonin Thyroxine Gastrin

In high concentrations, Epi and others cause:

Leukocytosis

At high doses of epinephrine __ receptors are more sensitive, but __ receptor effects predominate, leading to a ____ response:

β2 (decreased DP); α (increased DP); biphasic

Chief vascular action of epinephrine is on the components:

Smaller arterioles | Precapillary sphincters

Metabolic effects of epinephrine:

Hyperglycemia Hyperlipediemia Increased calorigenic action Hypokalemia

___ is CI in pregnant women due to it's lack of ___ receptor sensitivity:

Norepinephrine; β2

Adverse effects associated with epinephrine:

``` Cerebral hemorrhage (α1 BP effects) Cardiac arrythymias (β1) Skeletal muscle tremors (β2) ```

Therapeutic uses of epinephrine:

``` Anaphylactic shock Prolong local anesthetics Control of hemorrhage Cardiac arrest Chronic angle glaucoma Acute bronchial asthma ```

CI for epinephrine:

Patients on non-selective beta blockers | Patients with CAD

Unlike epinephrine, norepinephrine is associated with reflex _____:

bradycardia (no β2 effects leads to tremendous BP increase)

Locked-lung syndrome:

Congestion of the bronchial mucosa caused by repeated administration is isoproterenol

Major use of dopamine:

Chronic refractory congestive heart failure

Dobutamine substitutes an ___ group in place of the amino group and is a ____ receptor agonist:

aromatic; dopamine and β1

The effect of dobutamine is more on ____ than on ____:

myocardial contraction (inotropic); heart rate (chronotropic)

CI of dobutamine:

Idiopathic hypertrophic subaortic stenosis

Therapeutic uses of phenylephrine:

Topical nasal decongestant Mydriatic (increase pupillary size) Vasopressor drug Paroxysmal supraventricular tachycardia

Rebound congestion is minimal if:

The drug is taken orally

Ephedrine has a receptor sensitivity profile identical to ___:

Epinephrine

Ephedrine has this mode of action:

Direct and Indirect

Amphetamine is an ____ acting agent increasing ____ release and duration:

indirectly; norepinephrine

Therapeutic uses of amphetamine:

ADHD Narcolepsy Obesity

Terbutaline is a ___ agonist and not easily metabolized by___:

β2; COMT

Clonidine is a ____ agonist associated with ____ when discontinued suddenly:

α2; rebound hypertension (sympathetic compensation)

General CI when using adrenergic drugs:

``` Hypertension Cerebral arteriosclerosis Hyperthyroidism Acute coronary disease Diabetes BPH Narrow angle glaucoma ```

α2 selective drugs have _____ effects:

Sympathetic depressant

α2 selective drugs used in wide angle glaucoma:

Apraclonidine | Brimonidine