Catechol-substituted phenoxypropanolamines: adrenoceptor activity in the anaesthetized cat.

1 The pharmacological actions of racemic noradrenaline, adrenaline, isoprenaline and N-t-butylnoradrenaline have been compared with those of their corresponding derivatives containing an oxymethylene (OXY) link between the ring and ethanolamine side chain. 2 The compounds were tested in the anaesthetized cat for their ability to produce positive chronotropic effects, bronchodilator actions, changes in perfusion pressure in the perfused hind limb and decreases in soleus muscle contractions. 3 All the OXY-derivatives were potent beta-adrenoceptor agonists. The inclusion of the oxymethylene link promotes selectivity for beta1-as opposed to beta2-adrenoceptor activity. 4 In comparison with the parent compounds, the OXY-derivatives of adrenaline and noradrenaline had very weak alpha-adrenoceptor stimulant effects.