Receptor |
Binding Affinity |
Effects |
Mechanism |
Agonists |
Antagonists
|
α1 |
NE > Epi >> Iso
|
- Smooth muscle contraction, ↑SVR, ↑MAP
- Mydriasis, urethral sphincter contraction
|
Gq → PLC → IP3/DAG → [Ca2+]i
|
- NE
- Phenylephrine (pure α1)
- Midodrine
|
α1 selective:
|
α2 |
Epi = NE >> Iso
|
- ↑SVR, ↑MAP
- ↓insulin release, ↓lipolysis, ↓aqueous humor production
|
presynaptic Gi → ↓AC → ↓cAMP → ↓NT release
|
- Dexmedetomidine
- Clonidine
|
Non-selective:
- Phenoxybenzamine
- Phentolamine
- Trazodone
|
β1 |
Iso > NE > Epi
|
- ↑Chronotropy (myocytes), ↑Inotropy (SA node), ↑SBP
- ↑Renin release/↑volume (JGA)
- Amylase secretion
|
Gs → ↑AC → ↑cAMP
|
- Dobutamine
- Isoprenaline
- Norepi
|
Cardiac Selective:
- Metoprolol
- Atenolol
- Esmolol
|
β2 |
Iso > Epi > NE
|
- Smooth muscle relaxation, ↓SVR, ↓DBP, ↓MAP
- Bronchodilation
- ↑Lipolysis, ↑Insulin release
- Relax uterine smooth muscle
- ↑aqueous humor production
|
Gs → ↑AC; → ↑cAMP → ↑PKA
|
- Albuterol
- Formoterol
- Isoprenaline
- Salmeterol
- Terbutaline
- Ritodrine
|
Non-Selective:
- Propranolol
- Nadolol
- Pindolol
- Timolol
- Carvedilol (anti-α1)
- Labetalol (anti-α1)
|
β3 |
Iso > Epi = NE
- Lipolysis
- Bladder detrusor relaxation
|
Gs → ↑AC; → ↑cAMP → ↑PKA
|
|
|