Adrenergic receptor
From Ganfyd
A complex membrane protein.
Adenergic receptor subtypes are:
- α1A
- α1B
- α1D
- α2A
- α2B
- α2C
- α2D
- β1
- present in the heart, and cause an increased heart rate
- Likely to be the one of importance when betablockers are used to treat heart failure. For example segregation of patients into AAA389AAA-beta(1)-adrenoceptor polymorphisms showed that carvedilol caused increasing left ventricular ejection faction in alleles: Arg389Arg > Arg389Gly > Gly389Gly[1]
- β2
- cause smooth muscle relaxation resulting in dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle and release of insulin.
- β3
- lipolysis, thermogenesis, intestinal smooth muscle relaxation and relaxation of the urinary bladder. Role in glucose homeostasis and energy balance
They are stimulated by adrenaline generally but a large number of pharmaceutical compounds exist that have more specific stimulatory (eg catecholamines or inhibitory actions (eg α-blockers and β-blockers).
| Agent | α1 | α2 | β1 | β2 | Comments |
|---|---|---|---|---|---|
| Actions | Vasoconstriction (peripheral, renal) | Peripheral sympathetic, CNS, pre-synaptic | Heart: rate & force | Vasodilation (peripheral, renal, lung) | |
| Agonists | |||||
| Noradrenaline | +++ | +++ | ++ | + | vasopressor |
| Adrenaline | ++ | ++ | +++ | +++ | Anaphylaxis, inotrope, CPR |
| Isoprenaline | +++ | +++ | |||
| Phenylephrine | ++ | Vasoconstrictor | |||
| Salbutamol | + | +++ | Bronchodilator | ||
| Dobutamine | +++ | ++ | Inotrope | ||
| Antagonists | |||||
| Phentolamine | --- | --- | |||
| Propranolol | --- | --- | |||
| Atenolol | --- | - |
