What is acetylcholine (ACh)?
Acetylcholine is a neurotransmitter chemical that functions inside all of the human body. It affects the autonomic nervous system and the central nervous system. Acetylcholine causes muscle contractions, regulates endocrine and sleep functions, and arouses reactions to pain. It is responsible for the supply of cholinergic agonists to cholinergic receptors.
The major functions of cholinisterase and acelycholinesterase (cholinergic agonists) are the contractions of smooth muscles, constriction of pupils, decreasing heart rate and BP, and increasing secretions.
That’s a lot of mumbo-jumbo.
Bottom line is that anticholinergics inhibit acetylcholine, thus blocking cholinisterase.
Who is given anticholinergics?
Patients with excess secretions (GI or Respiratory)
Patients with bradycardia
Why do we give this to these patients*?
We’re going to use Parkinson’s today as a great example. So, with a Parkinson’s patient, we picture the tremors, slowed movement, drooling, and rigidity. Those are the things that come to my mind when I hear “Parkinson’s”.
They have these problems because the body’s natural antagonist to acetylcholine, dopamine, is decreasing without reason. So we have a decrease in dopamine and an increase in acetylcholine. We have an increase in muscle contractions and secretions. This causes for very disorganized motor function.
When we give an anticholinergic, Atropine, its going to block acetylcholine receptors from contracting smooth muscles. We’ll see an improvement in tremors and rigidity. We will also see a decrease in secretions, and thus so, see a decrease in drooling.
It counteracts acetylcholine.
Whats the cons? (side effects)
Of course, with most medicines, we have side effects to watch for. Because these drugs decrease secretions, we want to watch for a dry mouth, blurred vision (because it dilates the pupils), tachycardia, and urinary retention.