Kruse - Cholinergic Agonists/Antagonists Flashcards
Cholinesterase hydrolyzes at what rates?
ACh > methacholine > carbachol = bethanechol
ACh mimetics act on receptors by:
- Direct acting mAChR and nAChR stimulants
- Indirect cholinesterase inhibitors
Two types of direct acting cholinergic agonists
- Choline esters
2. Akaloids
Choline ester names
ACh, carbachol, bethanechol
Alkaloid names
Muscarine, nictoine, policarpine
Choline ester:
Absoprtion -
Distribution -
Choline ester:
Absorption - poorly absorbed in CNS (quaternary ammonium groups)
Distribution - poorly distributed in CNS
Choline ester metabolism location
Metabolism - hydrolyzed by cholinesterase in GI
choline ester less active when given ___
PO
Alkaloid
Absorption -
Absorption - well absorbed from most sites (i.e. noctine thru skin)
muscarine (mushroom) ingestion is (toxic or not) and goes to what location
Toxic
Enters brain
Alkaloid metabolism
Kidney excretion»_space; acidification of urine accelerates clearance
Choline ester = Type of molecule = absorbed well?
Alkaloid = Type of molecule = absorbed well?
Choline ester = charged quaternary amine = not well absorbed
Alkaloid = uncharged tertiary amine = well absorbed
M1 location
nerves
M2 location
HEART, nerves, smooth muscle
M3 location
glands, smooth muscle, endothelium
M4 location
CNS
M5 location
CNS
Nm
skeletal muscle NMJ
Nn
postG cell body, dendrites, CNS
Gq M recetors
IP3, DAG
M1,3,5
Gi M receptors
Inhibit cAMP
M2, 4
Type of receptor and its action on skeletal muscle
nAChR
muscle contraction
ParaS effect of…
decrease/contract everything, except:
Dilation of aa and vv.
Stimulation of bronchial glands
Detrusor contraction; trigone and sphincter relaxation
Sweat, salivary, lacrimal, naspharyngeal secretion
ParaS eye - contraction of relaxation of iris sphincter and ciliary mm?
contraction to:
increase aqueous humor»_space; Schlemm»_space; ant chamber drainage
What are all cardiac actions mediated by?
M2 mAChR
PS innervation is less in ventricle or atria?
ventricles (so less physiological effect when activated)
Muscarinic agonists release what form endothelial cells to relax smooth muscle around blood vessels?
Endothelium Derived Relaxing Factor (EDFR)
EDFR is largely ___, which activates ___, and ___cGMP in smooth muscle.
Overall effect of this is: ____
NO»_space; activates…
GC»_space;
increases cGMP»
Overall: to relax smooth muscle
Small doses of ACh = ____ effect on CV
Large doses of ACh = ____ effect on CV
small = vasodilation = decrease BP and increased HR large = bradycardia and decrease AV node conduction + hypOTension
GI:
M__ mACHR required for direct activation of smooth muscle relaxation
M__ mAChR reduces cAMP = reduces relaxation (increased contraction)
M2
M3
NO receptor on sphincters
M3 mAChR
mAChR or nAChR greater # in:
- Brain
- SC
- Brain = mAChR
2. SC = nAChR
inhibitory mAChR role in brain results in
tremors, hypothermia, analgesia
Activation of nAChRs is dependent upon what?
dose
Nicotine’s effect (via nAChR) in CV system are primarily sympathomimetic or parasympathomimetic?
Effects?
sympathomimetic
hypERtension, tachy-bradycardia alternation
nAChR effects in GI/GU tracts are primarily sympathomimetic or parasympathomimetic?
Effects?
parasympathomimetc
nausea, vom, diarr, voiding of urine
Major clinical uses of direct acting cholinergic agonists:
- Eye (glaucoma, accommodative esotropia)
2. GI/GU tract (post-op atony, neurogenic bladder)
Glaucoma -
Muscarinic stimulants cause contraction or relaxation of the ciliary body?
Contraction
Glaucoma - muscarinic stimulants are replaced by what direct acting cholinergic agonist?
topical beta-blockers and prostaglandin derivatives
Accommodative esotropia looks like what?
cross eyed