Celiprolol, a compound possessing weak alpha 2-adrenergic antagonist properties in the dog.

: Studies were conducted to evaluate the effects of celiprolol on alpha-adrenergic stimulation of dog saphenous vein rings (postsynaptic effect) and on catecholamine outflow from the dog coronary circulation during sympathetic nerve stimulation in vivo (presynaptic effect). In venous rings, celiprolol, 10(-6) to 10(-4) M, shifted the concentration-response curve to BHT 920 in a concentration-related manner, but had no effect on the response to methoxamine at concentrations less than 10(-4) M. During continuous stimulation of the right stellate ganglion, celiprolol, 1-10 mg/kg i.v., increased the catecholamine concentration in the coronary sinus, while decreasing heart rate. In contrast, propranolol did not affect catecholamine concentration but decreased heart rate, rauwolscine increased both catecholamine concentration and heart rate, and clonidine decreased both catecholamine concentration and heart rate. These results are consistent with the hypothesis that celiprolol possesses weak alpha 2-antagonist properties in addition to its beta 1-blocking activity.