Role of endothelium and vasoconstrictor prostanoids in norepinephrine-induced vasoconstriction in isolated rat common carotid arteries

We investigated the role of endothelium and vasoconstrictor prostanoids in the norepinephrine (NE)-induced vasoconstriction of isolated rat common car otid arteries (CCAs). Isolated CCAs were cannulated with stainless steel ca nnulae by the cannula inserting method. NE was administered intra- or extra luminally by a single microinjection. For denudation of endothelium, the in timal surface was gently rubbed with a cotton pellet. NE produced dose-rela ted vasoconstricting responses in isolated arteries with intact endothelium . These responses were attenuated by pretreatment with denudation, OKY046, a thromboxane A(2) synthesis inhibitor or indomethacin. The residual respon ses after denudation were further blocked by OKY046 or indomethacin. All NE -induced responses were blocked by a single injection of prazosin. There we re no significant differences in responses between intra- and extraluminal administration of NE. These results show that most vasoconstriction induced by NE via alpha(1)-adrenoceptors in CCAs is dependent on vasoconstrictor p rostanoids distributed both in endothelium and vascular smooth muscle.