Vasodilator effect of urotensin II, one of the most potent vasoconstricting factors, on rat coronary arteries.

The effects of human urotensin II on coronary flow were studied in the perfused rat heart. Urotensin II transiently decreased coronary flow, then induced sustained vasodilatation. In the presence of a cyclooxygenase inhibitor, diclofenac, coronary vasodilatation was significantly inhibited. A nitric oxide synthase inhibitor, N(G)-nitro-L-arginine (L-NNA), attenuated the urotensin-induced vasodilatation. These data suggest that urotensin II modulates coronary flow through factors such as cyclooxygenase products and nitric oxide to elicit coronary vasodilatation.