Three stereoisomers of yohimbine (corynanthine, rauwolscine and yohimbine) have been used to characterize α-adrenoceptors in rat aortic strips. pA2 values for each antagonist were calculated using 3 different agonists ((-)-noradrenaline, (-)-phenylephrine and guanfacine) which possess varying affinities for α1 and α2 receptors. Mean pA2 values were not significantly different irrespective of the agonist used and the order of the potency was corynanthine > yohimbine > rauwolscine. The results are consistent with the presence of α1-adrenoceptors in rat aorta.
- Rat aorta