Sympathomimetics Flashcards
What sets the pace of the SA node and is responsible for the phase 4 depolarization?
I-f “the funny current”
What is the resting membrane potential of nodal tissue?
-60
What is the resting membrane potential of nodal tissue?
-60
Which phases make up the nodal action potential?
Phase 0, 3, 4
All Alpha 1 receptors ______ levels of _____.
Increase, Calcium
All Alpha 2 receptors ______ levels of _____.
Decrease, cAMP
Alpha 2 receptors decrease cAMP by _____.
Inhibiting adenylate cyclase
Stimulation of Beta receptors causes a(n) _______ in _____.
increase, cAMP
Which beta receptors has an equal affinity for norepi and epi?
Beta 1
Which beta receptor has a greater affinity for epi than norepi?
Beta 2
What do dopamine 1 receptors do?
relaxation of peripheral smooth muscle
Dopamine 1 receptors _____ adenylate cyclase causing ______ cAMP levels.
Stimulate, increased.
Where are dopamine 2 receptors primarily located?
Brain
Dopamine 2 receptors _____ adenylate cyclase and decrease ______.
inhibit, ???
Where is Dopamine synthesized?
CNS Neurons
Where is Epi synthesized?
Second-order neurons and the adrenal medulla (80%)
Where is norepi synthesized?
Second-order neurons, adrenal medulla (20%), and CNS neurons
What are examples of alpha 1 agonists?
Norepi, Epi, Phenylephrine
What are examples of alpha 1 antagonists?
Phenoxybenzamine, Phentolamine, Prazosin
What are examples of alpha 2 agonists?
Dex, Clonidine
What are examples of alpha 2 antagonists?
Yohimbine (OTC for alertness)
What are examples of beta 1 agonists?
Epi, Norepi, Dobutamine/Dopamine
What are examples of beta 1 antagonists?
Atenolol, Metoprolol
What are examples of beta 2 agonists?
Albuterol, Terbutaline
What is an example of a beta 2 antagonist?
Propranolol
Is it an alpha or beta receptor in the eye? What does it do?
Alpha, mydriasis (dilation)
What is the limiting factor in the synthesis of catecholamines?
Tyrosine Hydroxylase
What percent of norepi goes back to the presynaptic nerve for reuptake?
80%
What is the byproduct of the breakdown of Norepi?
Vanillylmandelic acid (VMA)
What do you test to test for VMA?
the urine
What is the following for Epi:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 0.01-.2 Onset: 30-60 sec Duration: 5-10 min Receptor/action: Alpha and beta agonist Effect: increase SBP, decrease DBP (wider pulse pressure) positive chronotrope and inotrope, vasoconstriction from alpha activation
What is the following for norepi:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 0.01-0.4
Onset: <1min
Duration: 2-10 min
Receptor/action: more alpha than beta agonism
Effect: Increase SBP AND DBP, increased coronary blood flow, potent vasoconstrictor
What is the following for Dopamine:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: Renal dose: 1-3mcg/kg/min Cardiac: 4-6 mcg/kg/min Vasopressor: >10mcg/kg/min Onset: 2-4 min Duration:<10min Receptor/action: Renal: D1 agonist, Cardiac: Beta 1 agonist, Vasopressor: Alpha 1 agonist Effect: D1: vasodilation, increased flow to organs B1: Increased SVR, CO, contractility A1: vasoconstriction
What is the following for Isuprel:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 0.02-.15mcg/kg/min Onset: Immediate Duration: 1-5 min Receptor/action: Beta 1 and 2 agonist Effect: Positive chronotrope and inotrope. Potent vasodilator=decreased systemic and pulmonary vascular resistance.
What is the following for Dobutamine:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 0.5-30mcg/kg/min
Onset: 1-2
Duration: <10min
Receptor/action: Beta 1 selective agonist
Effect: Positive chronotrope (AV conduction) and inotrope
What is the following for Phenylephrine:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 50-100mcg Onset: <1min Duration: 15-20min Receptor/action: Pure Alpha 1 agonist Effect: peripheral vasocontriction, increased SBP & DBP, reflex bradycardia, can also be a decongestant
What is the following for Ephedrine:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 5-10mg
Onset: immediate
Duration: 10-60min
Receptor/action: Mixed direct and indirect actions, both alpha and beta agonist.
Effect: increased CO, BP, HR, indirectly causes release of stored catecholamines.
Caution with MAOI’s, sensitize pt and can cause hypertensive emergency.
What is the following for Vasopressin:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: Bolus 2-4units, Infusion 0.02-0.04 units/min
Onset:
Duration:
Receptor/action: smooth muscle vasoconstrictor.
Effect:
What type of med is Terbutaline and what is it used for?
B2 agonist
What is an example of a phosphodiesterase inhibitor?
Milrinone
What do phosphodiesterase inhibitors do to cAMP?
Decreased hydrolysis (metabolism) of cAMP), resulting in increased concentrations in the myocardium and smooth muscle. Causes positive inotropic effects and smooth muscle dilation.
hat is the following for Milrinone:
Dose: Onset: Duration: Receptor/action: Effect:
Dose: 0.25-0.5mcg/kg/min
Onset: 5min
Duration: ??
Receptor/action: increases concentration fo cAMP
Effect: positive inotrope (increased contractility) and decreased pulm pressures.
Catecholamines are metabolized by what?
COMT
Noncatecholamines are metabolized by what?
MAO
Stimulation of alpha 1 causes:
vasoconstriction mydriasis urinary retention glycogenolysis inhibition of renin
Stimulation of alpha 2 causes:
decrease in cAMP which causes a decrease in NE production
decreased insulin
Stimulation of Beta 1 causes:
increased heart rate
increased contractility
increased renin
Stimulation of Beta 2 causes:
bronchodilation vasodilation inhibition of uterine contractions decreased GI motility decreased insulin secretion
What is the substance that turns tyrosine to LDOPA?
tyrosine hydroxylase
What is the substance that turns Dopamine to norepi within the venticle?
Dopamine beta hydroxylase
What breaks down NE in the synaptic cleft?
COMT
What breaks down NE after it re-enters the presynaptic nerve?
MAO
What 2 things block the reuptake of catecholamines?
Tricyclic antidepressants and cocaine