Preferential blockade of presynaptic alpha-adrenoceptors by yohimbine.
Strips of the rabbit main pulmonary artery were preincubated with 3H-noradrenaline. 3 X 10(-8) -- 10(6) M yohimbine enhanced the overflow of tritium and the smooth muscle contraction induced by transmural sympathetic nerve stimulation. The increase of the stimulation-evoked overflow of tritium was prevented by a high concentration of oxymetazoline. The results indicate that yohimbine is more potent in blocking the presynaptic than the postsynaptic alpha-adrenoceptors of the artery.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D010109:Oxymetazoline / Q000494:pharmacology; D011817:Rabbits; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects; D013569:Synapses / Q000187:drug effects*; D014662:Vasoconstrictor Agents; D015016:Yohimbine / Q000494:pharmacology*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D014662:Vasoconstrictor Agents; D015016:Yohimbine; D010109:Oxymetazoline