Simultaneous intravascular two-dimensional plus Doppler ultrasound is useful for evaluation of postischemic vasodilatation: Plasma NO(x)^- levels determined by the Griess method may not reflect the extent of postischemic NO-induced vasodilatation

Our objective was 1) to assess postischemic vasodilatation using simultaneous intravascular two-dimensional and Doppler ultrasound, and 2) to clarify whether plasma nitrite and nitrate (NO(x)^-) levels change during postischemic vasodilatation. The vascular cross-sectional area (CSA) was evaluated in 18 mongrel dogs, and the average instantaneous peak velocity (APV) in the iliac arteries after the 5-min occlusion of blood flow was determined. Plasma NO(x)^- levels were measured at the baseline, during the occlusion of blood flow, and 1.5, 3, and 10 min after recanalization. The %CSA significantly increased from 30 s to 7 min after the recanalization, and maximal vasodilatation was observed at 1.5 min after the recanalization (14.1 ± 0.9 to 15.8 ± 1.0 mm², p < 0.0001 vs. baseline). Plasma NO(x)^- levels were significantly reduced during the occlusion of blood flow and remained reduced at 1.5, 3, and 10 min after recanalization compared with the baseline values. We concluded that simultaneous intravascular two-dimensional and Doppler ultrasound is useful for assessment during postischemic vasodilatation, and that plasma NO(x)^- levels assayed with the Griess reagent do not significantly increase, even when maximal vasodilatation is observed.