Adrenergic Transmission

Front 1

What is the metabolic precursor of catecholamines?

Back 1

L-Tyrosine. An aromatic amino acid.

Front 2

α-methyl tyrosine

(methyl-p-tyrosine)

Back 2

Tyrosine analogue that blocks catecholamine synthesis.

Front 3

Reserpine

Back 3

Drug that blocks VMAT and causes vesicular depletion of NE. It does this by inhibiting pumps that create a proton gradient utilized by VMAT.

Front 4

Isoproterenol

Isoprenaline

Back 4

Non -selective β agonist. Works equally on β1 and 2. Used to treat bronchospasm, heart block and bradyarrythmias. By action on β1 it will increase HR, SV and CO. By action on β2 it will decrease TPR and BP.

Front 5

Dobutamine

Back 5

Non-selective β agonist. (β1>>β2). Used to treat congestive heart failure. It increases HR SV and CO.

Front 6

Salmeterol

Back 6

A selective β2 agonist for the treatment of asthma. Slow acting and used for prophylaxis. Side effects include adrenaline like actions, mainly vasodilation, anxiety increased hepatic and muscle glycogenolysis (tremors) and lipolysis.

Front 7

Albuterol

Back 7

A selective β2 agonist for the treatment of asthma. Fast acting. Side effects include adrenaline like actions, mainly vasodilation, anxiety increased hepatic and muscle glycogenolysis (tremors) and lipolysis.

Front 8

Terbutaline

Back 8

A selective β2 agonist for the treatment of asthma. Fast acting. Side effects include adrenaline like actions, mainly vasodilation, anxiety increased hepatic and muscle glycogenolysis (tremors) and lipolysis.

Front 9

Ritodrine

Back 9

Selective β2 agonist. Used to stop premature labor.

Front 10

Norepinephrine

Back 10

Agonist on α1, α2 and β1. Notice no effect on β2- it can never lower BP. By action on α1, it increases TPR and BP. By acting on β1 it increases HR, SV and CO with a resulting increase in diastolic BP, and pulse pressure. Potential reflex bradycardia.

Front 11

Epinephrine

Back 11

Adrenergic agonist at all receptors. Has a dose dependent response based on the higher sensitivity of β receptors. So at low doses, activity on β1 and β2 will casue increased HR, SV and CO with a concurrent DROP in BP (β2 vasodilation) This resembles the action of isoproterenol. At high doses α1 action begins to predominate and the increased HR and CO will be accompanied by increased BP (resembles the action of NE). Unlike NE it has β2 specific effects : on smooth muscle (bronchodilation, vasodilation, and uterus relaxation), and metabolic effects (Increased glecogenolysis, gluconeogenesis and lipolysis). Epinephrine reversal: the use of α1 antagonists to reverse hypertension to hypotension by allowing β2 action to predominate, done in order to prevent compromising CO due to reflexes.

Front 12

Amphetamines

Back 12

Releaser of NE/Epinephrine from the mobile pool. Contraindicated if patient is using MAOa inhibitors. MAOa is found in multiple tissues of the body, and metabolizes Epi, NE and tyramine. If it is inhibited, a larger mobile pool coupled with the effect of releasers may cause a hypertensive crisis.

Front 13

Tyramine

Back 13

A chemical found in red wine and cheese that is a Releaser of NE/Epinephrine from the mobile pool. Usage of MAO inhibitors may cause hypertensive crisis due to the increased mobile pool.

Front 14

Ephedrine

Back 14

Releaser of NE/Epinephrine from the mobile pool. Used in cold medication. Contraindicated if patient is using MAOa inhibitors. MAOa is found in multiple tissues of the body, and metabolizes Epi, NE and tyramine. If it is inhibited, a larger mobile pool coupled with the effect of releasers may cause a hypertensive crisis.

Front 15

Cocaine

Back 15

NE/Epi reuptake inhibitor.

Front 16

Tricyclic antidepressants

Back 16

NE/Epi reuptake inhibitors.

Front 17

Phentolamine

Back 17

Competitive, non-selective α antagonist. Used to treat hypertension and PCC, though due to it's competitive inhibition, is not the drug of choice.

Front 18

Phenoxybenzamine

Back 18

Non-competitive (irreversible), non-selective α antagonist. The drug of choice when treating pheochromcytoma.

Front 19

Doxazosin

Prazosin

Tamsulosin

Terazosin

Back 19

Selective α1 blockers. Used to treat hypertension and benign prostatic hyperplasia (via the relaxation of the sphincter trigone muscle). These two disesaes are often co -morbid, since patients are usually middle aged males.

Front 20

Yohimbine

Back 20

Selective α2 antagonist. Used in the past to treat ED and lowered libido.

Front 21

Mitrazapine

Back 21

Selective α2 antagonist that also acts on other receptors (different 5HT receptors). It is used as an antidepressant and appetite stimulant.

Front 22

Describe β2 specific effects on the body

Back 22

Blood vessels -Relaxation. Decreased TPR, diastolic pressure and afterload.

Uterus -Relaxation

Bronchioles - Dilation

Skeletal muscle -Increased glycogenolysis and contractility (tremor inducing)

Liver -Increased glycogenolysis and gluconeogenesis.

Pancreas -Increased Insulin secretion (little)

Front 23

Describe α1specific effects on the body

Back 23

Eye (radial muscle) - Mydriasis , no accommodation

Arterioles of the skin and viscera - Contraction. Increased TPR, diastolic pressure and afterload.

Veins - Contraction. Increased venous return, preload and systolic BP.

Male sex organs -Vas deferens emission.

Liver - Increased glycogenolysis

Kidney - Decreased renin release (remember when integrating the responses on the kidney, that β1 receptors have higher affinity to NE)