Noradrenaline Flashcards
What receptors does NA act on?
Adrenoceptors
What are the three biogenic amines, and what are they all synthesised from?
Dopamine, noradrenaline and adrenaline.
They are synthesised from tyrosine.
Outline the synthesis of adrenaline.
Tyrosine-> DOPA (tyrosine hydroxylase)
DOPA-> dopamine (AADC)
Dopamine-> noradrenaline (dopamine beta hydroxylase)
NA-> adrenaline (PNMT)
What is the sympathetic effect on the heart? Why?
Positive chronotropy and contraction velocity.
This is because NA acts on beta 1 receptors and decreases the pacemaker potential, therefore increasing heart rate and contraction force.
What effect does sympathetic activity have on the lungs/bronchi?
Causes bronchodilatation.
What G protein is associated with alpha 1 receptors and what is the result?
Q
Acts on PIP2 to give IP3 and DAG and therefore activates as causes increased intracellular calcium
What is the G protein associated with alpha 2 receptors? What is the result?
I
Acts on adenylyl cyclase and inhibits, therefore reducing cyclic AMP.
What is the G protein associated with beta 1 receptor? What is the result?
S
Acts on adenylyl cyclase, but activates it and therefore increases cyclic AMP, causing phosphorylation of proteins and positive chronotropy.
What is the G protein associated with beta 2 receptor? What is the result?
S
Activates adenylyl cyclase and therefore causes increased cyclic AMP. Causes vasodilation.
Where are beta 1 receptors found? (2)
Heart and kidneys
Where are beta 2 receptors found? (2)
Uterus and GI tract
Which of adrenaline and NA has greater effect on alpha receptors?
NA
Which of adrenaline and NA has greatest affect on beta receptors?
Adrenaline
How is NA terminated?
Taken back up into presynaptic knob by NA transporter and is either broken down or re packaged.
Where in the ANS does NA act?
In the sympathetic NS at the post ganglionic synapse.
