Possible Interaction: Epinephrine and Yohimbine

“In addition, we found that yohimbine causes a dose-dependent increase in plasma epinephrine , which had not been found in studies measuring catecholamines in venous plasma.”

“We conclude that yohimbine increases plasma NE levels by increasing the rate of NE release from sympathetic nerves, and probably increases epinephrine release from the adrenals.”

“Ex vivo platelet aggregation in response to epinephrine was inhibited during yohimbine , showing that non-innervated alpha 2-adrenoreceptors were inhibited.”

“The effects of epinephrine and norepinephrine were inhibited by prazosin (&agr;1 antagonist) and by yohimbine (&agr;2 antagonist), while dopamine's were inhibited only by prazosin.”

“The epinephrine action was inhibited by the ADRα2A antagonist yohimbine.”

“Aggregation in human platelet-rich plasma induced by adrenaline (10 microM) was blocked by yohimbine (5 microM).”

“8 The aggregatory responses to adrenaline and UK‐14304 in rabbit platelets and to clonidine in human and rabbit platelets, which can be induced by A‐23187, are blocked by yohimbine but not by prazosin or indoramin.”

“The alpha2-adrenergic receptor antagonist yohimbine completely abolished the induction of ABCB1 mRNA, the stimulatory effect of adrenaline on Rh123 efflux, and the growth-inhibiting effect of 5-FU.”

“The synergistic interaction of …-5 microM) and epinephrine (0.5-2 microM) … by alpha2-adrenoceptor blocker ( yohimbine ; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 …), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)).”

“The SPMA cases were strongly associated with insensitivity to YH (in contrast with non-SPMA cases) when epinephrine was used as an agonist.”

“Platelet pretreatment with yohimbine or 13-azaprostanoic acid, which are antagonists of the alpha(2)-adrenergic and thromboxane receptors, respectively, or with acetylsalicylate and indomethacin, both of which act as inhibitors of thromboxane formation, abolishes the potentiating effect of adrenaline.”