Possible Interaction: Vasoconstrictor Agents and Yohimbine

“The vasoconstrictor effect of 500 ng/ml alpha-methyldopa was fully inhibited in the presence of 10(-7) M yohimbine.”

“In pithed rats, the vasopressor effects of clonidine were antagonized both by yohimbine (1.0 mg/kg i.v.)”

“ Yohimbine blocked the vasoconstrictor effect of 10‐10‐10‐7 mol clonidine (an α2‐adrenoceptor agonist, topical application) by 44‐67.7% inhibition, respectively (P < 0.001).”

“The cumulative dose-response curve of ergotamine (1-100 micrograms/kg) vasoconstrictor effects was partially inhibited to the same extent by prazosin (1 mg/kg) and yohimbine (0.3 mg/kg).”

“ Coronary vasoconstriction produced by norepinephrine was resistant to prazosin, but was blunted by alpha 2-adrenergic blockade with yohimbine or idazoxan.”

“Prazosin and yohimbine blocked the vasoconstrictor but not the antinatriuretic response.”

“Unlike SGB-1534 and prazosin, yohimbine failed to inhibit the vasoconstriction induced by phenylephrine, but instead potentiated the vasoconstrictor response to saphenous nerve stimulation.”

“In the second series of experiments low to moderate doses of yohimbine potently inhibited the renal vasoconstriction of clonidine, was less potent on that induced by noradrenaline and did not significantly affect that of phenylephrine.”

“In additional dogs the inhibition by clonidine of heart … to continuous accelerator nerve stimulation (presynaptic effect), and the vasopressor effect of clonidine (post-synaptic effect), … antagonized by prazosin, phentolamine and yohimbine ; cumulative doses for 50% antagonism of the cardiac chronotropic … were 103, 50 and 13 microgram/kg i.v.,”