Adrenergic Agonists And Antagonists Flashcards
Low doses of atropine cause ________
↑ secretion of acetylcholine because it blocks the pre synaptic M2 receptor which normally inhibits the release of acetylcholine
NE does not cause bronchodilation because the ____ receptors are mainly found in bronchial smooth muscle respond to _____
β2; epinephrine
_________ express almost exclusively α1 receptors and thus NE and epinephrine cause ______
Skin blood vessels; constriction
________ and _______ receptors are found in smooth muscles of blood vessels in skeletal muscle
β2 and α1
β2 is a vasodilator
α1 is a vasoconstrictor
Low concentration of epinephrine will cause ________ in the blood vessels supplying skeletal muscle
Vasodilation; β2 are more sensitive to epinephrine than α1 receptors are
What do you expect to see in the vessels supplying skeletal muscle when giving a high dose of epinephrine?
Vasoconstriction: both α1 and β2 receptors will be activated but the α1 response is stronger than β2
What are the classes of adrenergic agonists?
- direct acting: endogenous catecholamines, β and α agonists
- indirect acting: releasing agents, uptake inhibitors
- mixed acting
At low concentrations of epinephrine, it will activate mainly ____ and_____
β1 (found in the heart) and β2
Large doses of epinephrine cause an ↑ in BP due to:
- ↑ ventricular contraction (β1 effect)
- ↑ HR (β1 effect)
- vasoconstriction (α1 effect)
What is the effect on blood pressure (diastolic and systolic) when given a low dose of epinephrine
- diastolic pressure ↓ because: ↓ in peripheral resistance because β2 receptors are more sensitive
- systolic pressure ↑ because: ↑ cardiac contractile force (β1 effect)
- HR ↑ (β1 effect)
NO CHANGE IN MEAN BLOOD PRESSURE
The effects of epinephrine on blood pressure depends on the dose and ratio of the _____ and____ response in various vascular beds
α1; β2
Epinephrine is the drug of choice for _______
Anaphylactic shock
NE has little action on _____ receptors
β2
What are the cardiovascular effects due to NE?
- peripheral vasoconstriction (α1)
- ↑ cardiac contractility (β1)
- ↑ systolic AND diastolic pressure → ↑ BP
- baroreceptor reflex will kick in an cause BRADYCARDIA
- CO is unchanged or ↓
What is the effect of NE on cardiac output?
Unchanged or ↓ :
CO = HR x SV (SV ↑ and HR ↓)
NE is used to treat _____
Shock because it ↑ blood pressure
If atropine is given before NE, then NE will cause ___________
Tachycardia
Atropine will block the M2 receptors in the heart (↓ HR) so then no baroreceptor reflex response → ↑ HR
What receptors can dopamine activate
Dose dependent but can activate: dopamine receptors, β and α receptors
Dopamine 1 receptors > β1 receptors > α1 receptors
What is the CVS effect on LOW rate of infusion of dopamine?
Activates D1 receptors in the renal and other vascular beds:
- vasodilation
- ↑ GFR
- ↑ in renal blood flow
- ↑ in sodium excretion
With intermediate rates of infusion of dopamine, it will activate _______ receptors in the heart causing ________ and also causes release of NE from nerve terminals
β1 receptors (NE does not effect β2 receptors);
↑ cardiac output
Intermediate rate of infusion of dopamine on:
Systolic pressure
Diastolic pressure
MAP
PVR
SBP: ↑
DBP: not changed significantly because only β1 is activated
MAP: ↑
PVR: unchanged
What is the effect of HIGH rates of dopamine infusion?
- with high rates will also activate vascular α1 receptors → vasoconstriction → ↑ BP and TPR
High rates of dopamine infusion also activates _______ receptors
α1 receptors in the vasculature
For treating shock, _______ to _______ rates of dopamine infusion are used
Intermediate to high
