Dear Annabelle,
I love a peanut butter and tuna sandwich. But when I was a kitten, my school outlawed peanuts. My classmate was super allergic to them. So, we had a rule to keep our friend safe. I packed plain tuna fish instead.
I talked about that with my friend Travis T. Denton. He studies medicinal chemistry and neuroscience at Washington State University.
He told me that epinephrine is the medicine people use for a serious allergic reaction called anaphylaxis. It comes in an auto-injector, or EpiPen.
This is what an auto-injector looks like. It delivers epinephrine really fast—so you can get better ASAP. Tokyogirl79, CC BY-SA 4.0
“The interesting thing about epinephrine is that it’s a chemical made by the body,” Denton said. “It’s also called adrenaline.”
The epinephrine in your body controls your stress response—also called fight or flight. It’s how you get ready to handle a threat.
Let’s say an angry bear charges you. Your body dumps epinephrine into your bloodstream. It tells your heart to beat faster and your blood vessels to narrow. It orders your lung muscles to relax. Now you’re ready to fight the bear or run away.
Epinephrine the medicine works the same way. If you have anaphylaxis, you get itchy and swell up. Your airways close so you can’t breathe. It’s an emergency.
So, you grab your auto-injector and stab it through your clothes, right into your thigh muscle.
The epinephrine immediately spreads through your blood. It reaches protein receptors all over your body. Epinephrine molecules fit into those receptors. It’s like a key slipping into a lock. Or a ball hitting a glove.
What happens next is a signal cascade.
Imagine you want to make your friend smile—but they’re on the other side of the room. You draw a funny picture and pass it to someone next to you. They pass it to the next person and the next person. Eventually your pal gets your message and gives you a goofy grin.
Your message traveled through many people to get to its destination. That’s like a signal cascade.
When epinephrine binds to the protein receptor, that protein changes shape and activates. It releases a messenger molecule. That messenger zooms to another protein. It activates that protein. The message travels to even more proteins.
Passing that signal from protein to protein is how epinephrine “tells’” your cells to tighten up your blood vessels or relax your muscles. It all happens super-fast.
When the blood vessels squeeze smaller, your blood pressure goes up. That reduces swelling. When your lung muscles relax, your airways open. Now, you can breathe again.
After using an auto-injector, you should call 911. You need a doctor to make sure the allergic reaction is totally over.
Doctors use epinephrine for other things, too. It can minimize bleeding during surgery—because it squeezes blood vessels. It can help with other conditions that cause scary-low blood pressure or difficulty breathing.
Epinephrine uses what we know about the body to help us out. And you’d (peanut) butter believe science is how we figured that out.
Sincerely,
Dr. Universe