Participation of endogenous noradrenaline in the release of ATP by high potassium in the rat caudal artery.

Potassium (40 mM) evoked the release of adenine nucleotides and adenosine in rat isolated caudal arteries. This release was abolished by bunazosin. Endogenous noradrenaline was also released. Furthermore, the high potassium-induced purine release was abolished by rubbing the lumen of the vessel. These findings suggest that the high potassium releases endogenous noradrenaline, which subsequently elicits the release of ATP and related purines by acting on alpha 1-adrenoceptors on the endothelial cell.