Possible Interaction: Phentolamine and Yohimbine

“Furthermore, the expressed receptor was strongly antagonized by yohimbine and cyproheptadine, and mildly antagonized by mianserin and phentolamine.”

“In the presence of phentolamine , the α-adrenoceptor antagonists yohimbine , rauwolscine and corynanthine decreased the evoked 5-HT-release concentration dependently.”

“ Yohimbine and methysergide also blocked PCP in high dosages, but other drugs with comparable alpha-noradrenergic and serotonergic blocking properties ( phentolamine , cyproheptadine, and cinnanserin) were ineffective.”

“However, phentolamine and the selective α2-adrenoceptor antagonists yohimbine and rauwolscine competitively antagonized the inhibitory effect of NA on [3H]NA release (respective pA2-values 7.5 and 8.3) and on [3H]5-HT release (respective pA2-values 7.7 and 8.2).”

“Furthermore, phentolamine (10(-8), 10(-7) and 10(-6) M), prazosin (3 x 10(-9) and 3 x 10(-8) M) and yohimbine (3 x 10(-8) and 3 x 10(-7) M) significantly reduced the electrical stimulation-induced contractions in the preparations.”

“In males, yohimbine was a more potent inhibitor than phentolamine , which was more potent than prazosin.”

“The magnitude of NRVL-SAP transfer function was significantly reduced by phentolamine or prazosin but appreciably enhanced by yohimbine.”

“ Yohimbine remarkedly inhibited the baroreceptor reflex responses; on the other hand, prazosin, corynanthine and phentolamine produced little inhibition of the responses.”

“ Phentolamine and yohimbine were competitive antagonists against noradrenaline in the arteries and the veins.”

“… phentolamine (71 nmol), a nonselective alpha-adrenoceptor antagonist, or prazosin (9.5 nmol), a selective alpha … without effect on NPY-induced feeding behavior, pretreatment with the alpha 2-adrenoceptor antagonist yohimbine (15 nmol) dramatically attenuated the stimulatory effects of NPY … food intake (by over 50%) and local eating rate.”