GENERATION OF REACTIVE OXYGEN METABOLITES BY THE LAYERS OF VASCULAR POLYESTER GRAFTS

The continuous exposure to blood components, including pro-oxidants, m akes the blood vessel wall susceptible to oxidative stress and free-ra dical-mediated reactions. The aim of this study was to determine the a bility of reactive oxygen metabolite generation, expressed by the cont ent of malonaldehyde (MDA) and 4-hydroxyalkenals in principal layers o f polyester grafts during 12 months' observation. The experiments were carried out on 24 mongrel dogs, in which polyester grafts were implan ted into abdominal aorta. Seven days and 1, 4, and 12 months after the operation the grafts were excised. The MDA and 4-OH-alkenal concentra tions were determined by the LPO-586 method (Bioxytech, France). It wa s found that the MDA concentration in the graft neointima was much hig her than in the aorta in the early phase after the operation (P<0.01). With the passage of time this concentration decreased and after 4 mon ths was similar to the values of the normal aorta. On the other hand t he MDA concentration in the neomedia and neoadventitia was much higher than in their aorta counterparts and became even higher in later peri ods (P<0.01). The investigations indicate that the generation of large amounts of lipid peroxides in graft neointima occurs only in the earl y postoperative period. However, intensive lipid peroxidation in neome dia and neoadventitia was observed throughout the whole experiment. Th ese changes can suggest that the reactive oxygen metabolites in graft principal layers are generated by neutrophils, while endothelial cells are of less importance.