I know, breathing and babies sound kind of unrelated. But that’s what you have to remember about beta-2! Activation of this receptor does two major things:
1. Bronchodilation (Some people say “-dilitation” by the way. It’s the same thing so don’t sneer!). This is very useful for asthma, as it widens the airways and let’s you breathe easier.
2. Relaxation of uterine smooth muscle. Huh? No, for real. Beta-2 receptors are on the uterus! When they are activated, the uterus relaxes. Therefore, if you or someone you love is going into preterm labor, they might get a beta-2 agonist to stop that baby!
Now, I know that I’ve been breaking these receptors down for you one by one. Now that you’ve got the gist of it, here I am to break some news to you. First of all DON’T HAVE AN ADRENERGIC ATTACK. You okay? Okay.
Remember when I said that the BEST DRUG EVER would be totally selective? And that there is no BEST DRUG EVER? Yeah. Well, most drugs are not selective. That’s where side effects come from! Most adrenergic drugs affect more than one receptor. Like epinephrine, for example. It’s actually an alpha-1, beta-1, and beta-2 receptor agonist. Some beta blockers mostly block beta-1 but also block beta-2 a little bit. So, just keep that somewhere in the back of your mind as we move on to the drugs later. But also remember: No matter how many receptors a drug affects, if you know what the receptor does, you know what the drug will do!