Fig. 4.

Effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) on nitrite-induced vasorelaxation under aerobic conditions (pH 7.4, 37°C). Aortic rings were first contracted with phenylephrine (10 μM), and ODQ (10 μM) or nitric oxide (NO) (3 μM) was then added either before or after nitrite (500 μM). A: representative tracing for the effect of ODQ pretreatment on the nitrite-induced vasorelaxation. B: representative tracing for the effect of ODQ on nitrite prerelaxed aortic ring and followed by the effect of NO. Ordinate, aortic tension expressed in grams (g); abscissa, time in min. Arrows show the time at which different agents were added. Each protocol was repeated at least 5 times, and findings were reproducible as shown.