α2A2-a | α2B | α2C | |
---|---|---|---|
Potency order | adrenaline > noradrenaline | ||
Selective agonists | Oxymetazoline2-b | ||
Selective antagonists | BRL 44408 (8.0) | ARC 239 (8.0) | ARC 239 (8.0) |
Prazosin (7.5) | Prazosin (7.5) | ||
Imiloxan (7.3) |
Antagonist affinities (number in parentheses) are expressed as approximate −log K i values. Adapted from Alexander and Peters (1999).
↵2-a α2A-adrenoceptors from rats, mice, and cows have a ≈20-fold lower affinity for yohimbine, rauwolscine, and oxymetazoline than do their human orthologs.
↵2-b Reduced efficacy agonist.