Possible Interaction: Methoxamine and Yohimbine

“However, we found that the effect of methoxamine in melanophores from Labrus ossifagus could be blocked by yohimbine (an alpha 2-AR antagonist) but not by equimolar concentration of prazosin (an alpha 1-AR antagonist).”

“Both the ipsilateral as well as the … 1- or the alpha 2-adrenergic agonist metoxamine or clonidine were impaired by previous injection into the … alpha 1- or alpha 2-adrenergic antagonist prazosin or yohimbine , respectively (0.25 microliter at the concentration of … both cases).(ABSTRACT TRUNCATED AT 400 WORDS)”

“All changes in posture and reflexes elicited by metoxamine or clonidine were impaired by previous injection into the same corticocerebellar area of the corresponding alpha 1- or alpha 2-adrenergic antagonist prazosin or yohimbine , respectively (0.25 microliters at 8-16 micrograms/microliters).”

“R(-)- and S(+)-YM-12617 and YM-12617 (pA2 10.4, 8.31 and 9.75, respectively) and prazosin (pA2 8.13), phentolamine (pA2 7.55) and yohimbine (pA2 6.44) competitively antagonized the contraction elicited by methoxamine.”

“ Methoxamine was without effect but the relaxation response to NE was antagonized by phentolamine, idazoxan, and yohimbine , which suggests that there are alpha 2 adrenoceptors on endothelial cells that mediate the release of EDRF.”

“ Yohimbine abolished the contractile response to methoxamine.”

“ Yohimbine , an alpha 2 blocker, attenuated the duration of immobility, either alone or in conjunction with various dosages of methoxamine.”

“ Methoxamine (4 mg/kg) … pretreated with yohimbine (3 mg/kg) induced a further decrease of SWS and REMS and an increase of W. Thus, pharmacological activation of alpha …- or blocking of alpha 2-adrenoceptors appears to decrease sleep and increase W. Further, blocking of alpha 1-adrenoceptors decreases REMS.”

“The effects of methoxamine on prostaglandin output (stimulation and depression) were antagonized by yohimbine and phenoxybenzamine.”

“2 The hypertensive effects of the selective stimulating agents methoxamine (alpha 1-agonist) and B-HT 920 (alpha 2-agonist) were effectively antagonized by the adrenoreceptor antagonists prazosin and yohimbine , respectively.”