Potent, highly selective α2 adrenoceptor antagonist and imidazoline I1 receptor ligand (pKi values are 7.87, 7.42, 5.74, 7.28 and < 5 for α 2A, α2B, α2C, I1, and I2 receptors respectively). Promotes insulin secretion, at a site distinct from I1 or I2 (the putative I3 receptor) in vitro and in vivo.