Lecture 5 Flashcards
Adrenergic Agonists are also called: (3)
Adrenoceptor Agonits
Sympathomimetics
Fight and flight
____ is the main SNS neurotransmitter.
Norepinephrine
Norepinephrine (noradrenaline), epinephrine (adrenaline), dopamine, and dobutamine are referred to as ________.
Catecholamines
____ is released from the adrenal medulla when stimulated by the SNS as a hormone.
Epinephrine
6 steps of norepinephrine:
1) Synthesis of norepi
2) Uptake into storage vesicles
3) Release of neurotransmitter
4) Binds to receptor
5) Removal of norepi
6) Metabolism
Norepinephrine is the main ___ neurotransmitter.
SNS
1) ____ is transported intracellularly and hydroxylated into dihydro-Phenoxyalanine (DOPA).
Tyrosine
Which step is the rate-limiting step of norepinephrine?
Synthesis (tyrosine to DOPA)
1) DOPA is then decarboxylated into ____.
Dopamine
2) Dopamine is transported into vesicles where some/most of it is converted into _____.
Norepinephrine
Epinephrine is released from the _____ when stimulated by the SNS as a hormone.
Adrenal medulla
3) The action potential reaches the neuron, ____ rushes into the cell, and the vesicles fuse with the cell at the synaptic junction releasing norepinephrine into the synapse.
Calcium
4) Norepinephrine diffuses into the synapse and binds to _____.
Either pre or post synaptic receptor.
4)The presynaptic receptors provide a ____.
Feedback loop
4) The postsynaptic receptors _____.
Trigger a response by the effector cell.
Tyrosine is transported intracellularly and hydroxylated into _______.
Dihydro-Phenoxyalanine (DOPA)
What 4 drugs are catecholamines?
Norepinephrine (Noradrenaline)
Epinephrine (Adrenaline)
Dopamine
Dobutamine
Epinephrine is released from the adrenal medulla when stimulated by the SNS as a _____.
Hormone
4) The __-synaptic receptors provide a feedback loop.
Pre
Epinephrine is released from the adrenal medulla when stimulated by the ____ as a hormone.
SNS
4) The __-synaptic receptors trigger a response by the effector cell.
Post
5) What are the 3 ways norepinephrine is removed?
Diffuses away
Metabolized by catechol-O-methyl transferase (COMT) on the postsynaptic membrane
Presynaptic membrane reabsorbs the norepinephrine
What is the most common way norepinephrine is removed?
Presynaptic membrane reabsorbs the norepinephrinet
6) What two ways can norepinephrine be metabolized?
Reused by presynaptic neuron
Degraded by monoamine oxidase (MOA)
___ receptors were identified because they have a relatively high affinity for norepinephrine.
Alpha 1
What are the 5 effects of Alpha 1 Agonists?
Increased vascular tone Increased SVR which increases BP Mydriasis (pupil dilation) Increased bladder tone Increased tension in prostate
____ are mainly located on pre junctional nerve terminals to create negative feedback loops.
Alpha 2 Agonists
What are the effects of Alpha 2 Agonists ?
Some GI and digestive effects
____ innervates smooth muscle of most non-cardiac origin.
Alpha 1 Agonists
Where are Alpha 2 Agonists being use increasingly more?
Human cardiovascular as a sedative
Alpha 2 Agonist example
Dexmedetomidine (Precedex)
___ receptors were found to have a high affinity for the anti-hypertensive drug Clonidine (Catapress).
Alpha 2
What 3 reasons make Alpha 2 Agonists good to use as a sedative for surgery?
Modulates DPB-induced inflammatory responses better than glucocorticoids.
Sympatholytic effects help ameliorate unwanted cardiovascular reflexes post-op
Significantly less respiratory depression post-op then other sedatives
___ receptors were found to have equal affinity for norepinephrine and epinephrine (but much less than isoproteronol).
Beta 1
Many tissues have some Beta 1, but it is mainly found in the ____.
Heart
___ receptors are involved in lipolysis.
Beta 3
Dexmedetomidine (Precedex) is a _____
Alpha 2 agonist
What does Alpha 1 Agonists innervate?
Smooth muscle of most non-cardiac origin
___ receptors have more affinity for epinephrine than norepinephrine (but less than isoproteronol)
Beta 2
Alpha 2 receptors were found to have a high affinity for the anti-hypertensive drug _____.
Clonidine (Catapress)
4 effects of Beta 1 Agonists
Positive chronotrope
Positive inotrope
Increased lipolysis
Kidneys release more renin
Favorite food for the heart during increased cardiac demand
Triglycerides
Beta 2 is mostly found in the ____.
Lungs
4 effects of Beta 2:
Mostly relaxation in skeletal muscles and liver and some organs
ALSO
Vasodilation in skeletal muscles and liver and some organs
Insulin release
Uterine muscle relaxation
___ mostly affects the vasculature.
Alpha 1
___ mostly affects the heart.
Beta 1
___ mostly affects CNS feedback loops to treat HTN ad provide sedation.
Alpha 2
___ mostly affects the lungs.
Beta 2
____ essentially has an effect on all the other adrenergic receptors.
Dopamine
3 characteristics of dopaminergic receptors:
Positive Chronotrope
Positive Inotrope
Vasoconstriction at high dose
Beta 2 mostly affects the ____.
Lungs
Alpha 1 mostly affects the _____.
Vasculature
Beta 1 mostly affects the ____.
Heart
Alpha 2 mostly affects ____.
CNS feedback loops to treat HTN and provide sedation.
____ acts as both a hormone and neurotransmitter.
Adrenaline
____ is the archetypical adrenergic response.
Adrenaline
Cardiovascular effects of epinephrine.
Powerful positive inotrope and chronotrope (B1)
Increase CO, Increased myocardial O2 consumption
Constricts arterioles to mucous membranes, viscera, and skin (Alpha 1) and dilates arterioles to the liver and skeletal muscles (B2)
Causes kidneys to release renin (B1) –> profound vasoconstriction
What is the overall effect on blood pressure by epinephrine?
Increased SBP
Decreased DBP
Epinephrine respiratory effects
Profound bronchodilation by Beta 2
Epinephrine metabolic effects
Profound hyperglycemia
Liberates fat energy stores
What causes the profound hyperglycemia effect of epinephrine?
B2 causes the pancreas to release glucagon and stimulates the liver both increasing gluconeogenesis.
How can epinephrine be administered?
IV, IM, SQ, ET
NOT PO
How is epinephrine degraded?
MAO
COMT
How is epinephrine excrete?
Urine
What is the relevance of epinephrine to perfusion?
Code Hypotension and shock Anaphylactic reactions/shock Asthma/bronchoconstriction In conjunction with local anesthetics (like lidocaine)
What is the dose of epinephrine given during a code?
1 mg IV/IO every 3-5 minutes
Which type of hypersensitivities could epinephrine be used for?
Type 1 (Anaphylactic reactions/shock)
Typical adult epinephrine dose
2 to 10 mcg bolus PRN to effect
1 to 10 mcg/min titrated to effect
Typical pediatric epinephrine dose
- 05 to 10 mcg/kg bolus
0. 05 to 0.5 mcg/kg/min infusion
Norepinephrine is also known as:
Noradrenaline
Levophed
Levarternol
Norepinephrine is an ____ transmitter.
endogenous
What receptor effects does norepinephrine have?
Alpha and Beta 1 but little Beta 2
Cardiovascular effects of norepinephrine
Profound vasoconstriction due to alpha but without the vasodilator effects of Beta 2
Increased SBP and DBP
Increased SVR
Positive inotrope (B1) but little chronotropic change
What does norepinephrine cause little chronotropic change?
Baroreceptor refex arcs
Dose, half-life, route of norepinephrine
0.5 to 12 mcg/min titrated to effect in adult
short half-life
given by bolus or infusion
Not given SQ
Dopamine has ___ receptors at higher doses.
Alpha
Dopamine has ___ receptors at lower doses.
Beta
Cardiovascular effects of dopamine
Positive inotrope and chronotrope via Beta 1
Vasoconstriction at high doses (Alpha 1)
Renal and visceral effects of Dopamine
Increased renal blood flow and visceral perfusion via D receptors
Rate and effects of low dose dopamine
1 to 2 mcg/kg/min
Vasodilation to kidneys, brain, and viserca
Rate and effects of medium dose dopamine
2 to 10 mcg/kg/min
Increased cardiac output
Rate and effects of high dose dopamine
> 10 mcg/kg/min
Alpha activity predominates with profound arterial and venous vasoconstriction
4 instances that dopamine will be used
Cardiogenic or septic shock Renal failure Hypotension* CHF* *particularly in patients with low-outpu renal failure
___ is the synthetic an along of dopamine
Dobutamine (Dobutrex)
What receptor does dobutamine work on?
Beta 1 selective agonist
What are the effects of Dobutamine (Dobutrex) compared to Dopamine?
Greater inotropic
Less chronotropic
Dobutamine half life with IV infusion
about 10 minutes
Adult dobutamine dose
2 to 20 mcg/kg/min titrated to effect with heart rate not increasing > 10% above baseline
Drug-of-choice for cardiogenic or septic shock
Dopamine
Dobutamine is the ____ analog of dopamine.
Synthetic
Pediatric dobutamine dose
2.5 to 10 mcg/kg/min
How dose dobutamine cause increase CO?
It increases SV
Dobutamine causes ____ increase in myocardial O2 demand than the other catecholamines.
Less
What is a good short term example to use Dobutamine?
Short-term support for patients with CHF like patients struggling to come off CPB
What receptor does Prenalterol work on?
Partial Beta 1 selective agonist
How can Prenalterol be administered?
PO or IV
____ is a strong positive chronotrope and positive inoptrope and potent vasodilator (B2 effects)
Isoproterenol (Isuprel)
Isoproterenol (Isuprel) is a ____ catecholamine B1 and B2 selective agonist.
synthetic
What are the cardiovascular effects of isoproterenol (Isuprel)?
Increase CO
Decrease after load
What receptors are involved with Phenylephrine (Neo-Synephrine)?
Relatively alpa-1 selective agonist
Is Neo a catecholamine derivative?
No
Cardiovascular effects of Neo
Potent vasoconstrictor
Increases SBP and DBP
Has little effect on the heart, but causes reflex tachycardia
____ is mostly used as a cardiac stimulant in emergency situations (usually as a 2nd line drug).
Isoproterenol (Isuprel)
Is Neo inactivated by COMT?
No and because it isn’t it has a longer duration.
When is phenylephrine commonly used in perfusion?
in adult perfusion to increase SVR/arterial pressure
What receptors are involved with Isoproterenol (Isuprel)?
B1 and B2 selective agonist
____ is commonly used as a nasal spray for decongestant.
Neo
Typical phenylephrine bolus dose and frequency in adult CPB.
50 to 200 mcg until desired effect
Typical pedi neo dose
0.05 to 0.5 mcg/kg
Phenylephrine is mostly ___.
Alpha
Epinephrine is _____.
Non-selective
Isoproterenol is mostly _____.
Beta
____ is also used to treat SVT.
Neo
Examples of mixed-action adrenergic agonists
Ephedrine
Pseudoephedrine
Ephedrine and pseudoephedrine are sort of ______.
Broad spectrum sympathomimetics
Effects of ephedrine and pseudoephedrine: (4)
Cardiac stimulation
Elevated SBP and DBP
CNS stimulation
Bronchodilation
Ephedrine is still used clinically as a _____, but rarely.
Vasopressor
6 side effects of adrenergic agonists:
Arrhythmias Insomnia HA Nausea Hyperactivity Tremors
____ is metabolized into dopamine in the brain.
Levodopa
Does Levodopa cross the blood-brain barrier?
No
Levodopa is useful treatment for ______.
Parkinson’s Disease
What causes Parkinson’s Disease?
Degeneration of dopamine-producing cells in the brain.
_____ is useful treatment for Parkinson’s Disease.
Levodopa
