Rilmenidine reveals differences in the pharmacological characteristics of prejunctional α_2-adrenoceptors in the guinea-pig, rat and pig

摘要

The α_2A and α_2D-adrenoceptor subtypes are thought to be species homologs most easily differentiated on the basis of the potency of antagonists. In the present study we have compared the effect of rilmenidine with two other selective α_2-adrenoceptor agonists, UK-14304(5-bromo-6-[2-imidazolin-2- ylamino]-quinoxaline) and clonidine, against electrically-evoked contractions in five isolated preparations from the rat, guinea-pig and pig, and, where possible, determined the receptor subtype involved. Uk-14034, clonidine and rilmenidine produced concentration-dependent inhibition of the electrically- Evoked contractions of the rat isolated vas deferens and tail artery and the guinea-pig ileum.