Antagonist/agonist-preferring alpha-adrenoceptors or alpha 1/alpha 2-adrenoceptors?

Yohimbine and some stereoisomeric alkaloids inhibited the binding of 3H-clonidine and 3H-WB-4101 to rat cerebral cortex membranes. Rauwolscine and yohimbine had much higher affinity to the 3H-clonidine than to the 3H-WB-4101 site, whereas the reverse was true for corynanthine. The results indicate that the 3H-clonidine site is an alpha 2-adrenoceptor and not an agonist-selective site whereas the 3H-WB-4101 site is an alpha 1-andrenoceptor and not an antagonist-selective site.