I'll try to explain about the heat/acetylcholine issue. I may be covering things you already know about but I'm not going to assume you know it.

In MG, antibodies attack the neuromuscular junction. Because of that, we don't get enough acetylcholine and our muscles get weak with activity or sometimes just at rest. The antibodies themselves don't make people with MG heat intolerant. It's what heat does to the chemical reactions between acetylcholine and acetylcholinesterase that is the problem.

Acetylcholine is the "gas" that makes everyone's muscles work well and stay strong. It enters the neuromuscular junction - where the nerves and muscles meet - and goes to work. Acetylcholinesterase is an enzyme whose "job" it is to clean up after acetylcholine once it's "done" doing its job.

Mestinon is a cholinesterase inhibitor. It inhibits that enzyme from cleaning up acetylcholine so that we can use it longer. You may not know that other cholinesterase inhibitors are: caffeine, nightshade foods and organophosphates (pesticides).

The basic science is that extremes of heat and cold will increase acetylcholinesterase in the body, thereby eating up more acetylcholine. People with MG already have too little acetylcholine getting to their muscles due to destruction of the neuromuscular junction muscle receptors. Basically, our muscle gas tank runs low all the time. So heat, and that little enzyme, make us much weaker.

Here is a quote from the abstract I gave you: "Given that acetylcholine is released from cholinergic nerves during whole body heating, . . . " The more acetylcholine that is released, the more acetylcholinesterase is produced. It's the body's checks and balances for making sure "normal" people don't have too much acetylcholine. So the more people are heated up, the more acetylcholine we make and the more that enzyme thinks it needs to get rid of it! That's fine if you don't have MG but if you do, it simply eats up what we can't afford to lose.

The body has so many "signals" and biochemical reactions like this that it is amazing how we stay healthy. There is so much that can go wrong. Probably the one most people know about is water balance and how when we are dehydrated, our bodies retain fluid for us. And when we are overhydrated, it gets rid of the water.

Does that make sense?

Dysautonomia is different than MG. If I were actually awake this morning, I could go into the details of that too! If you look up autonomic nervous system and acetylcholine you may get the info you need on that. Or autonomic nervous system and Mestinon or cholinesterase inhibitor.

I hope you are doing okay and are able to manage your disease well. The autonomic diseases are actually more difficult to treat/manage than MG, although it all depends how bad off you are with either disease!

Annie