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Parasymphathetic Agents (Agonist & Antagonist) Cheat Sheet by

Summary of Parasympathetic Nervous System of ANS

Muscarinic ACh receptors (mAChRs) Location

Muscarinic 1 (M1)
Ganglia cells
Muscarinic 2 (M2)
Cardiac muscle
Muscarinic 3 (M3)
Sweat glands
Muscarinic 4 & 5 (M4 & M5) are NOT very important in this module.

Muscarinic Effects on Organ

Heart
↓HR
M2
Eye (circular musc.)
Pinpoint pupil
M2 & M3
Eye (cilliary musc.)
Contract
M3
Vascular musc.
Relax
M3 (NO)
Lungs (Broncho mus.)
Contract
M3
GI-tract
↑ motiility
M3
Genito­-ur­inary musc.
Contract
M3
Sweat & Salivary Gland
↑ excretion
M3

Parasy­mpa­thetic Agonist Effects

Heart
↓ CO = ↓ contra­ction & ↓ AV conduction speed = BRADYc­ardia
Vascular musc.
Vasodi­lation via (NO) production
Smooth musc.
↑ intestine & bladder tone (motility) & ↓ sphincter tone
Eye
↑ contra­ction of sphincter (miosis) & ciliary muscle (NEAR vision)
Glands
↑ sweating, saliva, gastric acid secretion
Parasy­mpa­thetic Agonist = Activation = INactivate sympat­hetic actions
(Think OPPOSITE of ALL sympat­hetic activa­tion)

Parasy­mpa­thetic Antagonist Effects

Heart
↑CO = ↑AV node firing = ↑ HR = TACHYc­ardia
Vascular musc.
NO EFFECT b/c NO innerv­ation
Smooth musc.
Relaxation = ↓GI & Urinary tract contra­ction
Eye
Pupil dilation & Loss of NEAR focus (FAR vision)
Glands
↓ sweat, saliva, gastric acid secretion
Central NS (CNS)
Belladonna Symptoms
Belladonna Symptoms: "mad as a hatter, red as a beet, blind as a bat, hot as hell, dry as a bone"

Eye Termin­ology

Miosis
Paralysis of ciliary muscle (loss of accomm­oda­tion, ability to focus)
Mydriatic
Contra­ction of pupil (leads to pinpoint pupil, ie. Ach)
Cyclop­legia
Relaxation of pupil (dilat­ion); Atropine: belladonna compound)

Antago­nist: Parasy­mpa­tho­lytic Agents

Antimu­sca­rinic
Block ACh in Parasymp. Effector Junctions
Antini­cotinic
Block ACh in Ganglia (Para- & Sympathic; NN/N1)
Antini­cotinic
Block ACh in NMJ (skeletal muscle relaxant, NM/N2)
 
Antini­cotinic
Block ACh in Ganglia (both Para- & Sympat­hetic, NN/N1)
 

Agonist: Parasy­mpa­tho­mimetic Agents

Direct­ly-­Acting: Combine with mACh and/or
nAChs cholin­oce­ptors receptor directly → Direct activa­tion.

Parasy­mpa­thetic Agents

Agonist
(1) Acetyl­cho­line, ACh (2) Bethanecol (3) Piloca­rpine (4) Methac­holine
Antagonist (-tropine)
(1) Atropine (2) Scopol­amine (3) Homatr­opine (4) Benzot­ropine (5) pirenz­epine

Direct­ly-­Acting PNS Agonist

mAChs
Choline Ester
Acetyl­cho­line; Methac­holine
   
Carbachol; Bethan­echol
 
Alkaloids
Muscarine; Piloca­rpine
nAChs
Ganglionic Stimulants
Acetyl­cho­line; Nicotine
   
Vareni­clinie (partial)
Choline Ester: Short-­acting; stay in blood stream; NO (X) BBB
Alkaloids: (X) BBB

mAChs Agonists Uses

Acetyl­choline
Ophthalmic (brief miosis)
Methac­holine
Belladonna poisoning; Urinary retention
Bethan­echol
Reverse post-op GI depression
Piloca­rpine (alkaloid)
DOC for Glaucoma

Acetyl­cho­lin­est­erase Inhibitors (AChEIs)

Reversible
Edroph­onium (Tensilon)
For myasthenia gravis (extreme muscle weakness)
Irreve­rsible (comp. Inhibs)
Neosti­gmine
NO (X) BBB; For myasthenia gravis & ileus
 
Physos­tigmine
(X) BBB; For glaucoma and for treatment of belladonna poisoning
 
Pyrido­sti­gmine
Myasthenia gravis
 
Ambenonium
Myasthenia gravis
Slow Reversible
Echoth­iophate
Glaucoma
 
Organo­pho­sphate insect­icides, nerve gases DFP
N/A
Inhibits AChE at both mAChs & nACh via ↑ synaptic concen­tration & half-life of Ach.

Symptoms from Excess Cholin­ergic activity

General (SLUDE)
Saliva­tion, Lacrim­ation, Urination, Diarrhea, Emesis
Muscarinic (SLUGBAM)
Saliva­tio­n/Sz, Lacrim­ation, Urination, GI distress (D/V), Bronch­oco­nst­ric­tion, Abd. cramps, Miosis
Nicotinic (MTWThF)
Mydriasis, Tachyc­ardia, Weakness (musc. paraly­sis), hyperT­Hermia, Fascic­ulation
 
Muscarinic (SLUGBAM)
Saliva­tio­n/Sz, Lacrim­ation, Urination, GI distress (D/V), Bronch­oco­nst­ric­tion, Abd. cramps, Miosis
 

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