The expression of VCAM-1 was rarely seen on days 0, 2, and 4 (Fig 2
, panels A, E, I, and M). The expression of VCAM-1 was observed in the endothelium of an hypertrophied muscular artery, newly muscularized small vessels, and capillaries on days 8, 16, and 22 (Fig 2, panels B, C, F, G, J, K, N, and O). In quantitative analysis of immunohistochemical findings, the endothelial expression of VCAM-1 was significantly up-regulated on days 8, 16, and 22 in the muscular arteries (Fig 2, panels D and H) and small pulmonary arteries (Fig 2, panel L), and on days 16 and 22 in the capillaries (Fig 2, panel P). VCAM-1 expression, as evaluated by double immunofluorescent staining with anti-vWF antibody, was localized to the inner surface of the endothelium in the hypertrophied arteries (Fig 2, panels Q to T) and newly muscularized arteries (Fig 2, panels U to X) in MCT-injected rats. Consistent with the VCAM-1 expression, the nuclear expression of active p65 subunit of NF-κB, which is unmasked in the absence of IκB, was not observed on days 0, 2, and 4 in any layers of the medium-sized muscular arteries and small peripheral arteries (Fig 3
, top left, A, and bottom left, D), but was strongly seen in the endothelium of hypertrophied arteries and newly muscularized small arteries on days 8, 16, and 22 (Fig 3, top middle, B, top right, C, bottom middle, E, and bottom right, F).