6.1 Adrenergic Flashcards
What are the adrenoreceptors?
Alpha
Beta
Dopamine
Where are Alpha 1 receptors found?
Mostly found in vascular beds, and bladder base, urethral sphincter, and prostate
What is the affect of an Alpha 1 agonist?
Arterial and venous vasoconstriction = BP up
What is the mechanism go Alpa 1 agonists? In normal pts? In pts with impaired ANS?
In normal pts–> baroreflex function kick in–> vagal tone increase–> slow heart rate–> counteract elevation of BP
Impaired autonomic function pts extremely hypersensitive to stimuli because loss of “baroreflex buffering”
= pt very sensitive to medication because baroreceptors can’t detect the elevation of BP and can’t respond to compensate
IMPLICATION- eg Parkinsons has some autonomic dysfunction, use A1 agonists with these pts, may see an exaggerated response
What are the effects of Alpha 2 agonists?
When stimulated, causes vasoconstriction increase blood pressure PERIPHERALLY
When stimulated, epi/norepi outflow slowed = sympatholytic effects lower BP CENTRALLY
What is the effect of Alpha 2 agonists on the CNS?
Pure agonist: impair sympathetic tone (sympatholytic) –> lower BP
Ex- Clonidine, anti HTN- a central-acting A2 agonist, when given to a pt with intact ANS, have a slowdown of autonomic outflow, and BP decreases
What happens to a pt with ANS failure and Alpha 2 agonists?
Central agonist can INCREASE BP
med stimulates A2 receptor in brain, doesn’t reduce the outflow or does not affect the outflow, so stimulation of peripheral A2 stimulation masks stimulation of A2 central
Where are Beta-1 receptors found?
HEART
What are the cardiac effects of Beta-1 agonists?
Heart rate (positive chronotropy)
Contractility (positive inotropy)
Conduction between AV node (positive dromotropy)
=increase cardiac output
Where are Beta-2 receptors found?
peripheral vasculature, bronchial smooth muscle
Where are Beta-3 receptors found?
Adipose tissue- increase lipolysis
What do Beta-2 agonists do?
Bronchodilation
Peripheral vasodilation
Where are dopamine receptors?
In cerebral, coronary, splanchnic, and kidneys blood vessels; and presynaptic neurons
What do dopamine agonists do?
Vasodilation
What receptors does epi effect?
A1, A2
B1, B2
What are the effects of epi?
Very potent vasoconstrictor and cardiac stimulant
Positive inotropy and chronotropy
Vascular beds vasoconstriction
Skeletal muscle blood vessels dilation (i.e via beta-2 stimulation)
What are the toxicities of epi?
Restlessness Throbbing HA Tremor Palpitation Cardiac arrhythmias Cerebral hemorrhage
What receptors does NorEpi work on?
A1, A2
B1
What is the effect of NorEpi?
Pressor
Increase peripheral resistance
Increase BP (systolic and diastolic)
What is extravasation? What is the risk with NorEpi?
Infiltrate into tissues from IV
Closes down capillaries –> shuts down perfusion –> badness (dead tissue)
Why is lido mixed with epi?
Makes the lido stay in place… epi vasoconstricts which keeps the local anesthetic local
What are the contraindications to norepinephrine?
Severe volume depletion Vascular thrombosis Profound hypoxia Use of MAO inhibitor Hyperthyroidism
What are the side effects of norepinephrine?
HA, anxiety Bradycardia Dyspnea Severe HTN Asthma exacerbation arrhythmias
What are the cardiac effects of epi vs norepinephrine?
Epi: + HR, + cardiac output
Norepi: - HR, - or no change to cardiac output
What are the BP effects of epi vs norepinephrine?
Norepi is the pressor… use
Epi will raise systolic, not as much for diastolic
What are the peripheral circulation effects of epi vs norepinephrine?
Epi: - peripheral resistance, + cerebral blood flow, +++ muscle blood flow (fight vs flight)
Norepi: ++ peripheral resistance, - or no change to cerebral/muscle flow
Epi or norepinephrine for the spleen?
Epi
What are the metabolic effects of epi vs norepi?
Epi: (Think fight or flight) + O2 consumption, + blood glucose, + lactate, + eosinophil response
NE: No change in O2 or blood glucose
What is the precursor to epi, NE?
Dopamine
What is the function of dopamine?
Na+ excretion
CNS–> reward center
Regulation of movement in basal ganglia
What pathology comes from a defect of domaine in the basal ganglia?
Parkinsons
What are the indications for dopamine?
Cardiogenic shock
Septic shock
What are the contraindications to dopamine?
Pheochromocytoma- tumor on adrenals that up Epi/NE
Tachyarrhythmias
Occlusive vascular dz
What are the side affects of dopamine?
Tachycardia/angina/HTN
HA/N/V/Anxiety
Extravasation tissue necrosis
What receptors does dopamine target?
Low dose: dopamine receptors
Medium doses: B1
Big dose: A1
What does dobutamine target?
B1
What metabolizes catecholamines?
MAO
COMPT
