Cholinergic Rs and Drugs Flashcards
Carbachol
Synthetic agonist that acts on both MRs and NRs and is resistant to AChE
Methacholine
Synthetic agonist that works very well only on MRs and is slightly susceptible to AChE
3 Direct Acting Cholinomimetics
Nicotine
Muscarine
Pilocarpine (partial agonist)
2 Indirect-Acting Cholinomimetics
Neostigmine - reversible AChE inhibitor
Sarin - nerve gas, irreversible inhibitor
AChE Inhibitor Effect on Blood Vessels
Little endogenous ACh, so minimal effect
Cholinomimetic Effect on CV System
In blood vessels, works on M3 smooth muscles to contract but more powerfully on M3 in endothelials, activating NO synthase so you get dilation. This causes drop in blood pressure and CNS sympathetic activation so that will counter the effects on the heart with unpredictable results
3 MRs in Brain
1, 4, 5
M2 Location/Function
Decrease pacemaker, conduction velocity, and contractility of heart
M3 Location/Function
Vascular endothelium increases NO release and is also in glands
Effects of Pilocarpine/Bethanechol
Muscarinic Cholinergic Agonists non selective forall MR subtypes so you get decreased HR from M2 and increased NO from M3 so bradycardia and hypotension
6 Effects of Muscarine
M2 bradycardia, and m3 Bronchoconstriction, GI motility, pupil constriction, sweating, and salivation
Use of Topical Pilocarpine
Preferred treatment of glaucoma for miosis and open canal of Schlemm
Paradoxical Effect of Pilocarpine
Might cause hypertension and tachycardia, due to possible post gang symp neurons and adrenal medulla w/ M1
2 System Inhibition of Cholinergic Agonists
May act on MRs at nerve terminals, inhibiting NT release from both systems
Atropine
MR inhibitor, so you get blockage of vagal tone and tachycardia
CNS Use of CholinoR Blocking Drugs
Some Parkinson’s patients, reduces tremors
Scopolamine
CholinoR blocker for motion sickness suppresses emesis, but also causes sedation, dry mouth, and amnesia after surgery
Eye Function of Atropine
Used to cause long term mydriasis (opening of pupil) for examination, but don’t use if testing for glaucoma bc need to see w/out dilation first
2 Uses for Neostigmine
Indiect cholinomimetic, so used for myasthenia gravis and urinary/GI retention
Benzatropine
CholinoR blocker w/ tertiary amine, so uncharged, so can cross BBB and treat parkinson’s
Ipratropium
CholinoR blocker w/ quaternary amine, so stays in periphery and blocks MRs in vessels so inhaled for asthma
