Cholinergic agents (drugs)

[Epona]

Hi all. I have a question about Cholinergic drugs. My Pharm. teacher told us that cholinergic drugs 'slow down' the system. Ok. She used the acronym SLUDGE. It stands for Salivation, Lacrimination, Urinary Incontinence, Diarrhea, Gastrointestional cramps, and Emesis to explain what these drugs do to the body. She also said these drugs slow the heart rate and cause bronchial constriction. Ok.. Here is where I am confused. To me, salivation, urinary incontinence, diarrhea, throwing up and so forth are sped up reactions. If it was slowing down wouldn't you have constipation, urinary retention?? I am confused. Help!!

[ready4crna?]

Cholinergics can effect a Parasympathetic-like response due to stimulation of muscarinic receptors.

The "slow" down term is really a reference to an overall increase in parasympatheic tone vs. a "speed" up of sympathetic stimulation.

A good place to start in understanding the Autonomic nervous system would be your physiology text, focusing hard on what Acetylcholine and Norepinephrine do in this system. This will help you understand the why's of the SLUDGE mnemonic a little better.

[GilaRRT]

I think instructors sometimes use oversimplified terms to describe the physiology behind our job. I never agreed with the whole speed up or slow down paradigm of explaining the nervous system.

For example, if I give you something that binds to a nicotinic parasympathetic receptor and mimics the action of acetylcholine, am I not stimulating that receptor?

Look at it this way. The body essentially has two types of cholinergic receptors. Or receptors effected by acetylcholine. So, a cholinergic response is a response caused by the action of acetylcholine on those receptors and anticholinergic is a response to blocking the action of acetylcholine. For example, nerve agents and organophosphates prevent the action of the enzyme acetylcholinesterase. Thus, allowing acetylcholine to remain attached and continue stimulating the cholinergic receptors.

**On a side note: I am talking about the post ganglionic action of acetylcholine, as pre-ganglionic receptors will all be acetylcholine receptors.

The two receptors you will most likely talk about are nicotinic and muscarinic.

Muscarinic receptors are associated with the salivation, lacrimation, vasodilation, etc. we often associate with a cholinergic response.

Nicotinic receptors are associated with the neuromuscular junction and muscle contraction.

Also remember, some substances are more specific to certain receptors.

[aeauooo]

Here's another one for you:

DUMBELS: Diarrhea, Urination, Miosis, Bronchospasm, Emesis, Lacrimation, Salivation

[Epona]

I happen to see my doctor yesterday and he tried to explain it to me. He said I cannot think of it as 'it all slows down' or 'it all speeds up.' He said Cholinergic drugs do different things to different organs and tissues. He said it stimulates smooth muscle (gut, bladder, etc.) but slows down heart muscle and lung tissue (hense slower HR and bronchi constriction). He was saying it bascially depends on the tissue and I guess where Ach is located on the synapse. That helped explain it to me. I was thinking that it slowed down or sped up all systems in a broad sense... not necessarily.

Thanks for all the replies!!

[bluegirlfriend]

Well, I think urinary continence is on there, because if you are relaxed, you are able to go to the bathroom. If your body is not relaxed, it is a bit harder to pee, in lamen terms. Have you noticed how your urge to urinate goes away when you are hyper-excited? I don't know if this is scientifically correct, but that's how I think about it.

[Jonathank]

The first reply hit the nail on the head. A cholinergic enhances parasympathetic responses.