Involvement of prostanoid release in the mediation of UTP-induced cerebrovascular contraction in the rat

The interaction between uridine-5 ' -triphosphate (UTP) and prostanoids was studied in isolated rat middle cerebral arteries (MCAs). The strong contra ctions in MCA segments induced by UTP were weakened significantly by indome thacin and more markedly by the thromboxane receptor antagonist ICI 192605. Thromboxane A(2) (TXA(2)) release by MCAs was below the detection limit of the chemiluminescence enzyme immunoassay, but increased TXA(2) formation w as detected in basilar arteries in the presence of UTP. Prostacyclin (PGI,) formation by MCAs also increased in the presence of UTP. These results sug gest that UTP stimulates the release of both TXA(2) and PGI(2) from the rat MCA but the vascular effect of TXA(2) is dominant. (C) 2001 Elsevier Scien ce B.V. All rights reserved.