Lecture 5 - Sympathetic/Adrenergic Flashcards
What effect does the SNS have on the eye and what receptor is involved?
- Contraction of radial muscle of iris causing dilation
- Alpha 1
What effect does the PNS have on the eye and what receptor is involved?
- Contraction of circular muscle of iris by M3 (causing contraction of pupil)
- Contraction of ciliary muscle by M3 (causing near vision)
What effect does the PNS have on glands and what receptor is involved?
M3 stimulation causes watery secretions
What effect does the SNS have on glands and what receptor is involved?
- Beta adrenergic stimulation causes secretion of protein
- Alpha adrenergic stimulation causes vasoconstriction leading to less water & more concentrated secretions
What effect does the SNS have on systemic blood vessels and what receptor is involved?
- Contraction of skin and splanchnic vessels by alpha 1
- Relaxation of skeletal muscle vessels by MUSCARINIC
What effect does the PNS have on systemic blood vessels and what receptor is involved?
- Release of EDRF causing relaxation of vessels by M3
Which receptors does norepinephrine mainly stimulate?
Alpha 1 in vessels
Which receptors does epinephrine mainly stimulate?
Beta receptors in cardiac muscle
What effect does the PNS have on GI smooth muscle and what receptor is involved?
M3 causes smooth muscle contraction and sphincter relaxation
What effect does the SNS have on GI smooth muscle and what receptor is involved?
- Relaxation of smooth muscle by beta 2
- Sphincter contraction by alpha 1
What are the effector organs of adrenergic receptors?
- Cardiac muscle
- Smooth muscle
- Glands
Adrenergic receptors respond to ____ and _____
Norepinephrine and epinephrine
What are the main functions of the alpha 1 receptor?
- Vasoconstriction
- Pupil dilation
- Ejaculation
- Contraction of bladder and prostate
Where are alpha 2 receptors located?
Presynaptic junction
What are the functions of the alpha 2 receptor?
- Inhibit NT release, thus inhibiting sympathetic activation
- Cardiac vasoconstriction
- Inhibit insulin release
Are alpha 1 and alpha 2 opposites?
Nope
What is the primary medical importance of alpha 2 receptors?
CNS (neuronal) and hypertension
What is the function of beta 1 receptors in the kidney?
Renin release, causing vasoconstriction
What is the function of beta 1 receptors in the heart?
- Increase heart rate
- Increase force of contraction
- Increase velocity of conduction in AV node
What are the functions of beta 2 receptors?
- Bronchial dilation
- Vasodilation
- Glycogenolysis
- Glucagon release
What is the function of dopamine receptors?
Dilate renal blood vessels
What is an example of a drug that is an alpha 1 agonist?
Pseudophedrine and phenylephrine
What is an example of a drug that is an alpha 2 agonist?
Clonidine
What is an example of a drug that is a beta 1 agonist?
Isoproterenol and dobutamine
What are examples of drugs that are beta 2 agonists?
- Isoproterenol
- Terbutaline
- Albuterol (salbutamol, ventolin)
- Salmeterol
What is an example of a drug that is an alpha 1 antagonist?
- Prazosin and doxasin
- Tamsulosin
What is an example of a drug that is a beta 1 antagonist?
Propanolol
What is an example of a drug that is a beta 2 antagonist?
Propanolol
What is the function of adrenergic agonists?
Mimic action of norepinephrine, dopamine, and epinephrine
Are adrenergic agonists selective?
Can be selective or non-selective, but almost all are at least partially non-selective
What are adrenergic agonists used for?
- Hemodynamic compromise (shock, depressed cardiac rhythm)
- Bronchospasms
- Nasal and sinus congestion
- Often used in emergency situations
What does epinephrine stimulate?
Both alpha and beta receptors
Why is epinephrine given parenterally?
GI enzymes destroy the drug
Is epinephrine specific?
No, very non-specific and is metabolized very rapidly
What is epinephrine used for?
- Severe, acute bronchospasms
- Anaphylactic shock
- Cardiac arrest
- Adjunct to anesthetic
What are the side effects of epinephrine?
- Stimulant effects on brain
- Hypertension-induced hemorrhage
- Cardiac arrythmia
- Hyperglycemia in diabetics
What is norepinephrine used for?
To treat shock (increase blood pressure)
What is pseudophedrine used for?
Nasal decongestant
What is the function of cocaine?
Inhibits the reuptake of serotonin, norepinephrine, and dopamine
Is cocaine selective?
No
Amphetamine has the same function as ____
Cocaine
What is selegiline (levadopa) used for and what are its side effects?
- Parkinsons treatment
- Dry mouth, constipation, tachycardia
What is phenelzine used for and what are its side effects?
- Anti-depressant
- Dry mouth, constipation, urinary retention, mydriasis, hyperthermia, sweating, hypertension
What is amytriptyline used for and what are its side effects?
- Tricyclic antidepressant
- Urinary retention, pregnancy, myocardial infarction, congestive heart failure
What are side effects to alpha 1 activation?
- Stimulant effects -> sweats, manic behaviour, anxiety, paranoia
- Weight loss, hyperglycemia, hypertension, bradycardia
When is dobutamine used?
In congestive heart failure to increase cardiac output (beta 1 agonist)
What is albuterol used for?
Asthma, COPD
What do anti-adrenergic drugs do?
- Inhibit or block the effects of sympathetic nerve stimulation
- Most block alpha 1, beta 1, or beta 2 receptors
What is another name for alpha 2 adrenergic agonists?
Adrenergic antagonists
What does clonidine do?
Lowers blood pressure
What do prazosin and doxasin do?
Competitive blockers of alpha 1 receptors, so decrease blood pressure
What does tamsulosin do?
Treats prostatic hypertrophy and vasospastic (urinary) problems
What do alpha 1 antagonists do in congestive heart failure?
Cause decreased preload and afterload by decreasing peripheral resistance
Why are adrenergic agonists AND antagonists used together in treatment for congestive heart failure?
- One drug activates SNS receptors on the heart (beta 1) to increase cardiac output
- Different drug inhibit SNS receptors on peripheral vessels (alpha 1) to decrease peripheral resistance
What are the side effects to blocking alpha 1 receptors?
- Early on causes massive orthostatic hypotension, so start w/ low doses
- Vertigo
- Sexual dysfunction
- Reflex tachycardia
What are beta blockers used for?
To treat rapid pulse arrhythmias, hypertension, MI, and other heart problems
How do beta blockers treat heart conditions?
- Decrease contractility
- Reduce oxygen demand
- Slow conduction through AV node
What are 1st generation beta blockers?
Non-selective (block beta 1 and 2)
What are 2nd generation beta blockers?
Cardioselective (beta 1)
What are 3rd generation beta blockers?
Partially selective (with alpha 1 inhibition)
What is a side effect to 1st generation beta blockers?
Can cause bronchospasms
What does propanolol do?
- Decreases cardiac output
- Bronchoconstriction
- Reflex peripheral vasoconstriction
- Decrease glycogenolysis and glucagon secretion (amplifies effect on insulin in hypoglycemia)
What is timolol used for?
Glaucoma, by decreasing production of aqueous humour and intraocular pressure
Why were 2nd generation beta blockers developed?
To avoid the bronchoconstriction of beta 2 receptors
What are 2nd generation beta blockers used for?
To treat hypertension; especially good for diabetic hypertensive patients
What is an example of a drug that is a 2nd generation beta blocker?
Atenalol
What does carvedilol do?
Has higher affinity for beta 1 and beta 2, so it reduces heart rate significantly and may exacerbate asthma
What does labetalol do?
Has a higher affinity for alpha 1, so reduces blood pressure w/o effecting heart rate
When is labetalol used?
For pre-eclampsia and emergencies
Do beta 2 specific antagonists exist?
No
Beta 1 receptors are ____ selective
Heart
What is the primary concern for beta 2 receptors?
Bronchial dilation
Should beta blockers be given to a patient who is taking insulin?
No because it will cause them to go into hyperglycemia shock and possibly die
