Adrenergic Stimulants and Antiadrenergics Flashcards
How do most postganglionic neurons in the SNS signal the target?
Through release of EPI or NE
What are the 5 steps of the EPI and NE life cycle? And where do they occur?
- Synthesis (presynaptic cell)
- Storage (presynaptic cell)
- Release (presynaptic cell)
- Receptor binding (postsynaptic cell)
- Disposition (synaptic cleft; terminates signal)
What happens in the synthesis step (1st) of the EPI/NE life cycle?
Enzyme dopamine-B-hydroxylase uses precursor dopamine to make NE. EPI is a further enzymatic product of the metabolism of NE by phenylethanolamine N-methyltransferase
What happens in the storage step (2nd) of the EPI/NE life cycle?
NE or EPI is loaded into synaptic vesicles where it is protected from degradation and also kept in a ready to release format
What happens in the release step (3rd) of the EPI/NE life cycle?
Occurs in response to action potential that signals synaptic vesicle fusion with the synaptic membrane. NE or APE is released in the synaptic cleft.
What happens in the receptor binding step (4th) of the EPI/NE life cycle?
There are 2 major classes of adrenergic receptors: alpha adrenergic receptors and beta adrenergic receptors
What happens in the disposition step (5th) of the EPI/NE life cycle?
Occurs through reuptake of neurotransmitter into presynaptic cell wall where it is recycled. This terminates the signal. The reuptake transporter is called the Nerpinephrine Reuptake Transporter (NET)
What are the 2 types of adrenergic receptors?
- alpha (a1, a2) - Mainly excitatory [exception of a2]
- beta (B1, B2, B3). - Mainly inhibitory [exception of B1)
- a1 and B1 = excitatory
- *a2 and B2 = inhibitory
Where is a1 found?
Smooth muscle
Where is a2 found?
nerve terminals (presynaptic, inhibits NE release)
Where is B1 found?
Heart
Where is B2 found?
Lungs, GI tract, uterus, vascular smooth muscle, liver, skeletal muscle
Where is B3 found?
Fat cells
T/F: Activation of the receptor can either activate the target organ, or inactivate it (depending on the type of receptor on the organ)
True
What is the name for drugs that activate the SNS?
Sympathomimetic
What is asthma characterized by?
hyperreactiveitiy of airways - amount of muscarinic agonist (methocholine) required to decrease exhales air volume by 20% is about 1%-2% of what is required in a non-asthmatic to cause equivalent airway resistance
What are the 4 clinic hallmarks?
Recurrent bouts of:
- Coughing
- Wheezing
- Shortness of breath
- Chest tightness
Explain the pathogenesis of asthma
- Constriction of smooth muscle surrounding airway
- Swelling of mucosal lining
- Generation of abnormally thick mucous
How do we treat the constriction of the muscles surrounding the airways?
Bronchodilators
What adrenergic receptor is responsible for acting on the muscle in the lungs?
B2 (inhibit contraction)
What drugs are adrenergic receptor agonists?
- Epinephrine
- Pseudoephedrine
- Clonidine
- Dobutamine
- Albuterol
What drugs are indirectly acting adrenergic agonists?
- Amphetamine
2. Cocaine
G-protein coupled receptors role
Allow transduction of signal by releasing the stimulatory G-protein complex when bound by EPI or NE
Adrenergic antagonists compete with ____ for binding to the receptor.
NE or EPI
