alpha 2 agonists

Question 1

List the alpha 2 agonists

Answer 1

Clonidine, Guanabenz, Guanfacine (also methyldopa is an alpha 2 agonist prodrug)

Question 2

There are alpha 2 autoreceptors and alpha 2 heteroreceptors. What do the auto receptors do?

Answer 2

An autoreceptor is on the presynaptic neuron from which the neurotransmitter was released. It acts as a negative feedback receptor. When activated, alpha 2 auto receptors inhibit the release of NE from presynaptic neurons

Question 3

There are alpha 2 auto and heteroreceptors. What do the heteroreceptors do?

Answer 3

Alpha 2 heteroreceptors are on non adrenergic neurons that are adjacent to the presynaptic neuron. They bind up the NE that was released from the presynaptic neuron so that it will not get in the way of that neuron’s native neurotransmitter

Question 4

Alpha 2 heteroreceptor induces?

Answer 4

bradycardia, hypotension

Question 5

What MUST alpha 2 agonists do in order to lower BP?

Answer 5

They MUST penetrate the BBB because alpha 2 agonists in the peripheral vasculature actually vasoconstrict the blood vessels. In the CNS, alpha 2 agonists decrease sympathetic tone and decrease BP

Question 6

There are six clinical effects of alpha 2 agonsits. List them

Answer 6

1. Lower BP
2. No reflex tachycardia
3. CO and RBF are unaffected
4. Decrease plasma renin
5. Regression of LVH
6. Salt & Water retention

Question 7

adverse effects of alpha 2 agonists?

Answer 7

somnolence, dry mouth

Question 8

The prodrug methyldopa has a contraindication for anemic patients that are taking an iron compound. Why?

Answer 8

Iron chelates the alpha-methylnorepinephrine (active metabolite of methyldopa)

Question 9

All these alpha 2 receptors that we’re talking about that lower BP when activated are located?

Answer 9

Vasomotor center of the medulla

Question 10

Activation of alpha 2 in the peripheral vasculature would?

Answer 10

Vasoconstrict