Cholinergic agonists Flashcards
Synth of ACh
AcetylCoA +Choline = ACh; by choline acetyltransferase
Degr of ACh
ACh = choline + acetate; by acetylcholinesterase
ACh Rs are M, N or both?
Both
What kind of Rs are nAChRs and where are they?
Ligand-gated ion channels located in muscle, autonomic ganglia, adrenal chromaffin cells and brain
what kind of Rs are mAChRs?
GTP-binding protein-linked receptors
Where are M2 Rs and what do they do?
Found primarily in cardiac tissue and cause hyperpolarization through increased potassium conductance
Where are M3 Rs and what do they do?
Predominantly in smooth muscle and secretory glands and cause PI turnover and increased calcium influx
Ganglion N Rs are selectively blocked by ______
hexamethonium
Muscle N Rs are selectively blocked by ______
curare
GI effects of ACh
Increased tone (motility); relaxation at sphincters
Cardiac effects of ACh
Bradychardia and decreased conduction
Muscarine
Contained in some mushrooms (Inocybe and Clitocybe); ingestion causes muscarine poisoning
Which drug can reverse muscarine poisoning?
atropine
Methacholine
- AChE resistant
- may be used for bronchial hyper-reactivity test VERY carefully
- primarily muscarinic
Bethanechol
- bladder mAChRs
- used post-op
- prevent salivation
- BBB
Carbachol
-used in wide-angle glaucoma (last line)
Pilocarpine
- partial agonist
- miotic agent for glaucoma
- promotes salivation
- CNS
direct cholinomimetic
agonist
indirect cholinomimetic
AChE antag
contraindications
- asthma – may precipitate an attack due to M mediated bonchoconstriction
- urinary obstruction
- acid peptic disease – may induce gastric acid secretion
classes of cholinergic agonists
choline esters & muscarinics
Nicotine
-initially activates ganglion AChRs, which is then followed by R blockage resulting from persistent depolarization
Nicotine poisoning can cause ___
tachycardia or bradycardia, hypertension or hypotension, depending on the dose and timing.
Clinical uses of nicotine
not used clinically except nicotine patches to aid in the cessation of smoking
