L6 Adrenergics

Question 1

Release of noradrenaline

Answer 1

Noradrenaline stored in synaptic vesicles

AP-> fusion of vesicular membrane with neuronal membrane-> release of noradrenaline into synaptic gap

Question 2

Catecholamine synthesis

Answer 2

Tyrosine-> tyrosine hydroxylase-> L-DOPA -> DOPA decarboxylase -> Dopamine-> Noradrenaline

Question 3

Re-uptake of NA

Answer 3

Transporter molecules pump noradrenaline back up into nerve terminals from which it was released
Get NT out of synapse

Uptake 1 transporters: high-affinity
Important mechanism for terminating noradrenaline

Uptake 2 transporters: lower affinity
At tissues that the synaptic nerve is innervating

Question 4

Metabolism-break of NA

Answer 4

Monoamine oxidase MAO: breaks down some NA that is transported up to the nerve terminal
Catechol-o-methyltransferase COMT

both found in sympathetic neurons

Question 5

Drugs modulating release and inactivation of NA

Answer 5

Cocaine blocks the transporter molecule that is responsible for reuptaking noadrenaline
⇒ enhance the levels of noradrenaline in the synaptic cleft
⇒ increase in concentration & duration

Dopamine, similar
Enhanced levels of NT in CNS

Question 6

Inactivation-metabolism

Answer 6

MAO Monoamine oxidase-inhibitors Anti-depression agents
Block MAO, leakage of NA out of synaptic vesicles
Enhanced levels of NA in synaptic cleft-> aids in counteracting symptoms of depression

Question 7

Indirectly Acting Sympathomimetics

Answer 7

Ephedrine (psuedoephedrine)

Tyramine

Question 8

signal transduction through beta adrenceptors

Answer 8

Gs coupled to AC
Increases in cAMP
-> cellular effects

beta 1: increases force of contraction and heart rate

beta 2: dilation of bronchi-smooth muscle of lungs

Question 9

signal transduction through alpha 1 adrenceptors

Answer 9

Gs coupled to phospholipase C 
Increase in Ca 
2ndary msgers: 
IP3- release of intracellular ca-> constriction 
DAG-PKC activation

Question 10

signal transduction through alpha 2 adrenceptors

Answer 10

Gi coupled to AC
Inhibit/decrease AC
decrease cAMP
decrease NT release