Possible Interaction: Adrenergic Agonists and Yohimbine

“We essentially found that yohimbine not only blocks contractions induced by adrenergic agonists , but also by non-adrenergic substances, such as ET-1.”

“ Adrenergic agonists competed for [3H]yohimbine binding sites with an order of potency: clonidine greater than (-) epinephrine greater than (-) norepinephrine greater than (+) epinephrine much greater than (-) isoproterenol; adrenergic antagonists with a potency order of yohimbine greater than phentolamine greater than prazosin.”

“Potassium ions and the adrenergic agonists induced prompt melanosome aggregation that could be competitively blocked by yohimbine (alpha-2 specific adrenergic antagonist) and phentolamine (non-specific alpha adrenergic antagonist).”

“The inhibitory effects of the adrenergic agonists in SCG were blocked by the beta-adrenergic antagonist, propranolol (10 microM) and alpha 2-adrenergic antagonist, yohimbine (10 microM).”

“In this dose, yohimbine antagonized the inhibitory effect of the α‐adrenoceptor agonist clonidine (1 μg kg−1).”

“3 The α1‐adrenoceptor agonist , oxymetazoline and the antagonist prazosin inhibited the binding of [3H]‐yohimbine to rat cortex in a complex manner consistent with an interaction at more than one site.”

“ Yohimbine prevented the effects of clonidine on the secretions induced by both adrenergic agonists.”

“ Yohimbine (2 mg/kg) increased the ED50 values of neurotensin and adrenergic agonists.”

“2 Yohimbine reversed the inhibitory effects of the α‐adrenoceptor agonist , clonidine.”

“The GH‐releasing effect of clonidine (… infused iv over 10 min), an α2‐adrenergic agonist , was … yohimbine (30 mg orally at −50 min), a relatively specific α2‐adrenergic antagonist area under the response …±SEM: 672.6 ± 143.0 versus 219.6 ± 16.7 μg/l/h; P<0.05).”