Pharm - Autonomic Drugs (Cholinergic & Noradrenergic pathways)

Question 1

What neurotransmitter is released from cholinergic neurons? What are the steps leading up to this release?

Answer 1

ACh; Choline enters neuron (axon) => Choline + Acetyl-CoA => ChAT produces ACh => ACh packaged into vesicles => ACh vesicles released into synapse; See p. 245 in First Aid 2014 for visual

Question 2

What neurotransmitter is released from adrenergic neurons? What are the steps leading up to this release?

Answer 2

NE; Tyrosine enters neuron (axon) => Tyrosine => DOPA => Dopamine=> NE (packaged into vesicles) => NE vesicles released into synapse; See p. 245 in First Aid 2014 for visual

Question 3

What effect does Hemicholinium have on the cholinergic pathway?

Answer 3

Hemicholinium prevents intracellular influx of choline by reuptake

Question 4

What effect does Vesamicol have on the cholinergic pathway?

Answer 4

Veamicol prevents ACh from being packaged into intracellular vesicles

Question 5

What effect does Botulinum have on the cholinergic pathway?

Answer 5

Botulinum prevents presynaptic vesicle release of ACh by cleaving synaptobrevin

Question 6

What effect do AChE inhibitors have on the cholinergic pathway?

Answer 6

AChE inhibitors prevent the breakdown of ACh in the synaptic channel, by inhibiting the enzyme acetylcholinesterase

Question 7

What effect does Calcium have on the cholinergic pathway?

Answer 7

Calcium promotes the presynaptic vesicle release of ACh

Question 8

List 4 drugs acting on the cholinergic pathway. Which of these is generally not clinically used?

Answer 8

(1) Hemicholinum (generally not clinically used) (2) Vesamicol (generally not clinically used) (3) Botulinum (4) AChE inhibitors

Question 9

What effect does Metyrosine have on the noradrenergic pathway?

Answer 9

Metyrosine inhibits tyroisine hydroxylase (which normally catalyzes conversion of tyrosine to DOPA/dopamine; this is rate-limiting step of pathway)

Question 10

What effect does Reserpine have on the noradrenergic pathway?

Answer 10

Reserpine prevents the entry of dopamine into presynaptic vesicles

Question 11

What effect does Calcium have on the noradrenergic pathway?

Answer 11

Calcium promotes the presynaptic vesicle release of NE

Question 12

What effect does Bretylium have on the noradrenergic pathway? What other drug shares this effect?

Answer 12

Bretylium, guanethidine; Prevents presynaptic vesicle release of NE

Question 13

What effect does Amphetamine have on the noradrenergic pathway?

Answer 13

Amphetamine increases presynaptic vesicle release of NE (and, to a lesser extent, acts as a reuptake inhibitor)

Question 14

What effect does Cocaine have on the noradrenergic pathway? What other drugs share this effect?

Answer 14

Cocaine, TCAs, & Amphetamine prevent presynaptic reuptake of NE

Question 15

What are 2 release-modulating receptors of the noradrenergic pathway? What effect does each have?

Answer 15

(1) AT II - stimulate NE release (2) alpha 2 - inhibit NE release

Question 16

Explain the role that norepinephrine plays in its on regulation.

Answer 16

Release of norepinephrine from a sympathetic nerve is modulated by norepinephrine itself, acting on presynaptic alpha2-autoreceptors, angiotensin II, and other substances