Background: We examined the time course of endothelium-dependent and -independent responses in reversed autogenous arterial grafts during regeneration and tissue repair processes after arterial grafting in dogs. Materials and Methods: Autogenous arterial grafts implanted in the canine femoral artery were removed, cut into rings and suspended in organ chambers for isometric tension recording on the 1st, 3rd, 7th, 14th and 28th days after implantation. Electron-microscopic examination on the 1st, 3rd , 7th, 14th and 28th days after transplantation was also performed. Control arteries were taken from non-surgically treated femoral arteries. Results: Acetylcholine (ACh) and A23187 caused endothelium-dependent relaxations in arterial grafts throughout the study. Although endothelium-dependent relaxations to ACh and A23187 on the 3rd day after transplantation were only significantly impaired compared to those of control, they were similar to the control within 1 week after grafting. Smooth muscle relaxations in response to sodium nitro-prusside in arterial grafts throughout the study were comparable with those of control arteries. No apparent intimal thickening of the arterial grafts was observed. Electron microscopy scanning revealed mild endothelial cell damage in implanted autogenous arterial grafts on the 1st or 3rd day after grafting. Seven to 14 days after grafting, the endothelial cell layer appeared to be normal. Conclusions: It was observed that the endothelial function remained intact and there was an absence of intimal thickening in the arterial grafts. These observations may explain the improved patency of autogenous arterial grafts compared to the vein grafts in aortocoronary revascularization.
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