Exam 2 - Catecholamines & Their Receptors Flashcards
Where are adrenergic receptors found in the body, generally?
in effector tissues targeted by the sympathetic nervous system
What are the 3 main catecholamines of the sympathetic nervous system?
- dopamine
- norepinephrine
- epinephrine
Where are alpha-1 receptors found in the body? Function?
- wide spread
- contraction/constriction
Where are alpha-2 receptors found in the body? Function?
- presynaptic terminals
- negative feedback
Where are beta-1 receptors found in the body? Function?
- heart
- increase rate and contraction
Where are beta-2 receptors found in the body? Function?
- widespread
- relaxation/dilation
What two molecules start the synthesis of catecholamines?
tyrosine —> DOPA
What order are the 3 main catecholamines produced?
from DOPA:
* dopamine
* norepinephrine
* epinephrine
Where is dopamine formed in the body?
- adrenal medulla
- neuron terminal
Where is norepinephrine formed in the body?
- adrenal medulla
- neuron synapse
Where is epinephrine produced in the body?
adrenal medulla
What are the two enzymes involved in catecholamine metabolism?
- MAO
- COMT
What does MAO do to catecholamines?
- targets amine group
- deamination
What does COMT do to catecholamines?
- targets the hydroxyl group
- methylation
Which catecholamine is not affected by MAO?
epinephrine
What is the benefit/drawbacks of -OH removal on a catecholamine?
- increases duration of action by preventing COMT metabolism
- decreased drug potency
What is the benefit of substitution -CH2 group on a catecholamine?
blocks MAO metabolism
Sympathomimetics
- stimulates adrenergic transmission (adrenergic agonist) – albuterol
- hypotension
Sympatholytic
- inhibit adrenergic transmission (adrenergic antagonist)
- hypertension
B1-Gs Receptor
makes neurons more likely to fire (increases HR)
M2-Gi
makes neurons less likely to fire (decreases HR)
What do Beta Blockers do?
inhibit beta receptors in the heart – stops SNS control of heart
* decreases HR
* decreases contractility (B1-Gs)
