Partial agonist effect of 2-[2-(1,4-benzodioxanyl)]-2-imidazoline (RX 781 094) at presynaptic alpha 2-adrenoceptors in rabbit ear artery.
Ear arteries from rabbits were preincubated with 3H-noradrenaline and then perfused. 2-[2-(1,4-Benzodioxanyl)]-2-imidazoline (RX 781094) 0.1 or 1 microM reduced the overflow of 3H-noradrenaline and total tritium elicited by 13 electrical pulses at 0.25 Hz or 26 Pulses at 0.5 Hz. RX 781 094 1 microM increased the overflow elicited by 52 pulses at 1 Hz. The inhibitory effects were blocked by yohimbine 10 microM but not by prazosin 1 microM. The alleged antagonist RX 781 094 possesses intrinsic activity at the presynaptic alpha 2-autoreceptors of the ear artery.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004147:Dioxins / Q000494:pharmacology*; D004423:Ear / Q000098:blood supply; D004558:Electric Stimulation; D019329:Idazoxan; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000378:metabolism; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D004147:Dioxins; D011942:Receptors, Adrenergic, alpha; D009638:Norepinephrine; D019329:Idazoxan