Vascular leakage occurs at specific sites on a vessel despite uniform fMLP treatment. (a) Blood vessels are visualized with dextran, and neutrophils appear green on the image. When fMLP was used to activate neutrophils, the site of leakage was designated as S2 and the area where leakage did not occur was designated as S1 in the same blood vessel (blood leakage occurred at S2, with no apparent change in S1). Scale bar: 30 µ
m. See Video 2
. (b) When leakage occurred at S1 and S2, blood was extruded and the intensity of red was increased. The graphical display compares the intensity at two areas at 44 to 60 min in Video 2
. At the time of initial imaging (arrow), the intensity of S1 is higher than that of S2 because the background becomes reddish as overlap occurs due to motion during in vivo imaging. Graph B shows the percent intensity (%) of blood flow in the two areas, as measured by the leakage of dextran.