Figure 5b:

Intramural enzyme activity in focally injured rat aorta, measured in vivo by using dual-channel probe. (a) Graph illustrates fluorescence ratio profile calculated from three catheter imaging passes through representative rat focal aortic (Ao) injury. Peak ratio is approximately twice the peak ratio of inactivated probe. (b) Graph data indicate that intramural enzyme activity was readily detected and quantified by using the ratio technique in all four animals. Peak ratios at site of injury were approximately twice the peak ratio of inactivated probe. (c) Ex vivo catheter images of representative rat aorta show AF633 and AF750 signals from injury site. Red bar at top illustrates extent of area of focal injury. Increased AF750 and AF633 fluorescence is seen at area of focal injury (toward left of image) compared with fluorescence in uninjured area. Fluorescence in AF750 channel, representing signal from constitutively active fluorochrome, reflects local delivery of probe by means of extravasation into inflamed interstitium. Fluorescence in AF633 channel, representing signal from activatable fluorochrome, reflects protease activation of fluorescence. Ratio of the two signals serves as quantitative measure of protease activity that does not vary with blood attenuation effects. arb = arbitrary units.