ANS 3 Flashcards
Tyrosine Hydroxylase is inhibited by this substrate and is also the rate limiting step
Norepinephrine
A non-specific enzyme not confined to catecholamine synthesising cells
Dopa decarboxylase
A non-specific enzyme but is restricted to catecholamine synthesizing cells
Dopamine B-Hydroxylase
Main location is in the adrenal medulla and production is induced by a steroid hormone
Phenylethanolamine N-methyltransferase (PNMT)
Major factor that controls the rate of synthesis of epinephrine by increasing PNMT
Glucocorticoid
Storage of NE is contained in?
Vesicles
Maintained by VMAT
75% of NE is recaptured and repackaged mediated by?
Norepinephrine Transporter (NET)
25% by EMT
This enzyme degrades NE and is found in Mitochondria and abundant in Noradrenergic nerve terminals
Monoamine oxidase (MAO)
Degrades NE but absent in Noradrenergic nerve terminals but present in adrenal medulla
Catechol-O-Methyltransferase (COMT)
End product NE metabolism
Vanillylmandelic acid (VMA)
Synapse where the 2nd messenger is cAMP?
Presynaptic adrenergic receptors
Type of receptors found in the presynaptic membrane
a2, B2
Postsynaptic receptor where the 2nd messenger is phospholipase C?
a1
The rest is cAMP mediated
What type of presynaptic receptor decreases cAMP when activated?
a2
Main neurotransmitter found in postganglionic sympathetic fiber?
Norepinephrine
Main catecholamine secreted by the adrenal medulla?
Epinephrine
NT in the CNS?
Dopamine
- Can pass the BBB
- CNS stimulant action
- Longer Duration (COMT resistant)
Non-Cathecolamine
Direct acting Adrenergic agonist
Norepinephrine Epinephrine Isoproterenol Phenylephrine Dobutamine Terbutaline
(DirectT EPIN)
Rank of order for a1 potency
Epinephrine≥ Norepinephrine» Isoproterenol
Effects of NE stimulation to a1
Vasoconstriction (also for a2)
Pupil Dilation
Ejaculation
Effects of NE stimulation to a2
Decrease activation of cAMP
Inhibits release of NE and Ach
Decreases aqueous humor
Low insulin
Activation of B1
Heart: Inc Contraction, Inc HR
Kidney: Renin Release = Angiotensin
(Contraction)
Rank of order of potency for B1
Isoproterenol > Epinephrine ≥ Norepinephrine
