Comparative alpha- and beta-adrenoceptor activity of 2- and 6-ring-chlorinated noradrenaline analogues.

The alpha- and beta-adrenoceptor activity of the 2- and 6-ring-chlorinated analogues of noradrenaline (norepinephrine) were evaluated in vitro. The 2-chloro-substituted analogue exhibits a far greater affinity for beta 1-chronotropic receptors than the 6-chloro-substituted analogue, whereas no significant differences are apparent for their alpha-adrenergic affinities.