Muscarinic antagonist Flashcards
1
Q
What are muscarinic antagonist drugs?
A
- those that inhibit muscarinic receptors
- M1 = Gaq
- M2 = Gai
- M3 = Gaq
2
Q
What do muscarinic antagonist drugs do to the parasympathetic activity?
A
- reduce the activity
3
Q
Why are muscarinic antagonist drugs commonly called anti-cholinergic?
A
- muscarinic receptors are a form of cholinergic receptor
- inhibit muscarinic means anti-cholinergic
4
Q
What is one of the most commonly prescribed muscarinic antagonist drugs?
A
- atropine
5
Q
What is atropine used for in the heart?
A
- treat people with bradycardia
- patients have low HR
- patients may have lower CO
6
Q
What is the mechanism of action of atropine?
A
- competitive antagonist
- inhibits acetylcholine and therefore muscarinic receptors
7
Q
In a normal physiological response what does the muscarinic receptor M2 do to the heart?
A
- inhibit adenylyl cyclase (AC) as part of Gai
- ⬇️ AC = ⬇️ HR and inotropic contraction
8
Q
Atropine is a non selective competitive antagonist, meaning it can compete with acetylcholine and inhibit its activity when binding to muscarinic receptors. Although it has a wide range of effects, what does atropine do to the heart in patients with bradycardia?
A
- does not inhibit adenylyl cyclase (AC) in Gas
- ⬆️ activation of SA node = ⬆️ HR
- ⬆️ inotropic contraction
