title: Stimulation by vanadate of [3H]noradrenaline release from rabbit pulmonary artery and its inhibition by noradrenaline.
abstract: Vanadate, the +5 oxidation state of vanadium, present in mammalian tissues, even in nerve tissue, and a competitive inhibitor of NaK-ATPase, significantly enhanced the release of [3H]noradrenaline evoked from rabbit isolated perfused pulmonary artery by electrical stimulation. Its effect proved to be concentration-dependent. Noradrenaline (10(-6) M) reduced the vanadate-potentiated release of [3H]noradrenaline. The effect of noradrenaline is mediated via alpha 2-adrenoceptors as evidenced by the finding that yohimbine 3 x 10(-7) M prevented its action. The effect of vanadate was dependent on external K ions. When the effect of vanadate on [3H]noradrenaline release was studied under conditions when the NaK-ATPase enzyme activity was inhibited by removal of external K for 45 min, vanadate was ineffective. This finding indicates that the effect is related to the inhibition of NaK-ATPase activity, a condition known to result in transmitter release.
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D000316:Adrenergic alpha-Agonists; D011942:Receptors, Adrenergic, alpha; D014639:Vanadium; D014638:Vanadates; D000254:Sodium-Potassium-Exchanging ATPase; D009638:Norepinephrine