Abstract
The effects of adrenaline, noradrenaline and isoproterenol on rabbit ear vessels and the influence of pipratecol on their effects were pharmacologically investigated and the following results were obtained:
1) Pipratecol decreased the perfusion drops of rabbit ear vessels when 0.1ml of the drug was perfused in a concentration of 10-4,10-6, or 10-8g/ml.
2) The perfusion drops decreased by 0.1ml of adrenal ine or noradrenaline 10-10g/ml was prevented by pipratecol 10-4or 10-6g/m1 with which the preparation was pretreated 60 minutes before the affection of the adrenaline or noradrenaline. But, this kind of effect of pipratecol was scarcely seen when the drug was applied in the concentration of 10-8g/ml.
3 ) The slight increase in the perfusion drops, appeared when 0.1ml of isoproterenol 10-10g/ml was applied on ear vessels, was scarcely influenced by the pretrea tment with pipratecol in any concentration.
From these resul ts it was assumed that pipratecol acts on the a-adrenergic receptor of rabbit ear vessels.
