Vein graft arterialization causes differential activation of mitogen-activated protein kinases

Vein graft arterialization results in intimal hyperplasia. Representative hematoxylin and eosin–stained contralateral external jugular vein (C) and arterialized vein graft (AVG) at 28 days. White lines identify intimal hyperplasia. (40×, 100×.)

Vein graft arterialization induces bimodal ERK-1/2 activation. Representative Western blot comparing ERK-1/2 activation in contralateral external jugular vein (C) and arterialized vein graft (AVG) at the indicated time points after arterialization. Upper panel: membranes probed with anti-phospho-ERK-1/2 antibody (pERK-1/2); lower panel: membranes probed with anti-ERK-2 antibody (ERK-2). Densitometric analysis of ERK-1/2 activation in contralateral external jugular veins (gray bars) and arterialized vein grafts (white bars). Means ± SEM of 3 independent experiments are shown. Overall statistical significance is shown. Asterisk denotes significant difference from the control at each time point (P < .05) via GLM parameter estimates.

Vein graft arterialization induces bimodal p38^MAPK activation. Representative Western blot comparing p38^MAPK activation in contralateral external jugular vein (C) and arterialized vein graft (AVG) at the indicated time points after arterialization. Upper panel: membranes probed with anti-phospho-p38^MAPK antibody (p38); lower panel: membranes probed with anti-ERK-2 antibody (pp38). Densitometric analysis of p38^MAPK activation in contralateral external jugular veins (gray bars) and arterialized vein grafts (white bars). Means ± SEM of 3 independent experiments are shown. Overall statistical significance is shown. Asterisk denotes significant difference from the control at each time point (P < .05) via GLM parameter estimates.

Vein graft arterialization does not induce JNK activation. Representative Western blot of in vitro kinase reaction products comparing JNK activation in contralateral external jugular vein (C) and arterialized vein graft (AVG) at the indicated time points after arterialization. Upper panel: membranes probed with anti-phospho-jun antibody (p-jun); lower panel: membranes probed with anti-c-jun antibody (c-jun). Positive control (Pos) was obtained by lysing Madin-Darby canine kidney (MDCK) cells 10 minutes after irradiation with 20 mJ/cm² of UV-C. Densitometric analysis of JNK activation in contralateral external jugular veins (gray bars) and arterialized vein grafts (white bars). Means ± SEM of 3 independent experiments are shown. Overall statistical significance is shown.

ERK-1/2 and p38^MAPK activation occurs in medial and luminal cells after vein graft arterialization. Immunohistochemical staining of contralateral external jugular vein (C) and arterialized vein graft (AVG) with anti-phospho-ERK-1/2 antibody and anti-phospho-p38^MAPK antibody. (400×.)

Vein graft arterialization induces medial and luminal cell proliferation and apoptosis. A, Representative Western blot comparing PCNA expression in contralateral external jugular vein (C) and arterialized vein graft (AVG) at the indicated time points after arterialization. Upper panel: membranes probed with anti-PCNA antibody (PCNA). Densitometric analysis of PCNA expression in contralateral external jugular veins (gray bars) and arterialized vein grafts (white bars). Means ± SEM of 3 independent experiments are shown. Overall statistical significance is shown. Asterisk denotes significant difference from the control at each time point (P < .05) via GLM parameter estimates. B, Immunohistochemical staining of PCNA in arterialized vein graft (AVG) compared with contralateral external jugular vein (C) at 4 days. C, TUNEL staining shows increased apoptosis in arterialized vein grafts (AVG) compared with contralateral external jugular veins (C) at 8 and 24 hours. (200×.)

Vein-to-vein or artery-to-artery bypass does not induce MAPK activation or PCNA expression. A, Representative Western blot of ERK-1/2 and p38^MAPK activation in arterialized vein bypass grafts, vein-to-vein bypass grafts, and artery-to-artery bypass grafts at 30 minutes following arterialization. B, Representative Western blot of PCNA expression in arterialized vein bypass grafts and vein-to-vein bypass grafts at 4 days following arterialization. C, Control (contralateral external jugular vein, femoral vein and femoral artery, respectively); AVG, arterialized vein graft; V-VBG, vein-to-vein bypass graft; A-ABG, artery-to-artery bypass graft.