Relative affinities for alpha-1-R

Potencies for different receptors

These 4 graphics show the potencies of 3 agonists for the different adrenergic receptors.

The potency of the 3 agonists for the α1 and α2 receptors is similar: adrenaline and noradrenaline are equally potent for both receptors, whereas isoprenaline is less potent.

The 3 agonists display different potency patterns for

β1 and β2 receptors. Isoprenaline is the most potent for both β1 and β2. For the β1 receptor adrenaline and noradrenaline are both less potent than isoprenaline, but with about the same ED50. For the β2 receptor, noradrenaline is the least potent of all 3 agonists and adrenaline has intermediate potency.