cholinergic receptors Flashcards
muscarinic receptors
mAChR located on parasympathetic neuroeffector sites
mAChR’s mediate parasympathetic responses
M1
nerve cells
M2
heart and SM
M3
heart and SM
M4
SM and glands
M5
?
probably central NS
Blocks mAchR?
Atropine
Nicotinic receptors
nAchR located on autonomic ganglia
nAchR’s are also involved in neuromuscular transmission
Nm
Nn
Nm
nicotinic receptor
Neuromuscular
Blocks Nm receptors?
Tubocurarine
Nn
nicotinic receptor
autonomic ganglia, adrenal medulla and CNS
Blocks Nn receptors?
Trimethaphan
Cholinomimetic Direct acting drugs
interact with receptor
ACh, bethanechol, pilocarpine, carbachol, cevimeline, methacholine
Cholinomimetic Indirect acting drugs
Potentiate effect of ACh, inhibit AChase, nonspecific
Physostigmine
Neostigmine
edrophonium
Ach
non-specific = Muscarinic and Nicotinic
Poor side effect profile
IV small dose - transient fall in BP (generalized vasodilation) accompanied by reflex Tachycardia
Large dose = bradycardia or block of AV nodal conduction (direct action on heart)
Cholinergic agonists: Eye
Miosis
improved near vision
Cholinergic agonists: Heart and vasculature
Decreased HR, CF, conduction
Vasodilation
Cholinergic agonists: Lung
Bronchoconstriction
increased secretion
Cholinergic agonists: GI and glands
increased motility
relaxation of sphincters
increased secretion
Cholinergic agoinsts: Urinary bladder
contraction
relaxation of sphincters
Bethanechol
selective for GI and urinary tracts
Urinary retention*
reflux esophagitis
Carbachol
muscarinic and nicotinic
Mainly Glaucoma
cataract surgery
Reduces intraocular pressure and produces miosis