Cholinergic Agonists and Antagonists Flashcards
The muscarinic receptor is what kind of receptor?
GPCR
The nicotinic receptor is what kind of receptor?
Ligand gated ion channel
Generally, what functions does the parasympathetic NS have on the…eye, heart, bronchioles, GI tract, bladder?
Pupillary constriction Decreased chronotropy and inotropy Bronchiole constriction Increased GI motility Stimulate bladder emptying
What does the M1 receptor do?
Activates myenteric plexus to stimulate peristalsis in gut
What does the M2 receptor do?
Decreases HR. It hyperpolarizes SA node pacemaker cells by opening K+ channels and allowing K+ to flow out of the cell.
What does the M3 receptor do?
Contracts ciliary muscle in the eye to allow for accomodation.
Bronchiole smooth muscle- leads to bronchoconstriction.
Activates bladder detrusor muscle to cause urination.
Stimulates secretions of GI tract, sweat glands, tear glands, and salivary glands.
How does the nicotinic receptor function? What binds the receptor and what does that cause?
Ligand gated ion channel. Two Ach molecules bind the receptor, inducing a conformational change to allow Na+ to flow through and depolarize the membrane.
Name the two kinds of nicotinic receptors and where they are located.
Nm = located in skeletal muscle; promotes skeletal muscle contraction
Nn = located on neurons in the CNS, parasympathetic and sympathetic ganglia
What is the one medical use for nicotine?
Smoking cessation!
Transdermal patch to help relieve smoking addiction
Nicotine is a selective agonist for what receptor?
Nn receptor
How is Succinylcholine used clinically?
Muscle relaxant
How does succinylcholine produce its physiological effects?
Succinylcholine is an Nm agonist. It binds the Nm receptors and activates them constitutively, preventing propagation of the action potential. Prolonged depolarization of the membrane prevents Na+ channels from leaving their inactive state, preventing the propagation of the action potential.
Will acetylcholine cross the BBB? Why or why not?
No!
It is positively charged.
Is acetylcholine useful medicinally?
Not really. Cholinesterases will degrade Ach very quickly.
Methacholine acts primarily at what kind of receptors?
Muscarinic