Background. The aim of the study was to evaluate the activity of the key antioxidative enzyme - superoxide dismutase (SOD) and the content of the lipid peroxidation product - malondialdehyde (MDA) in the wall and mural thrombus of abdominal aortic aneurysms.
Material and methods. The studied material consisted of aneurysm walls and mural thrombi obtained during surgery from 36 patients. The aneurysm wall was stratified into the inner layer and the outer part, which was composed of media and adventitia. Mural thrombus was stratified into the external part - adhering to the aneurysm wall and the internal part - being in touch with blood. Aortas from organ donors served as controls. SOD activity was assessed according to Sykes method, whereas MDA content according to HPLC method in tissue homogenates.
Results. The lowest superoxide dismutase activity was found in the aneurysm wall. Furthermore, its inner layer showed 50% lower enzyme activity than the outer one. Superoxide dismutase activity was significantly higher in thrombus when compared to the aneurysm wall with a particular increase in its internal part. The highest MDA content was found in thrombus (without significant differences between its parts). The inner layer of the aneurysm wall showed more than a twofold higher MDA content than its outer layer. The lowest MDA content was found in the wall of normal aorta.
Conclusions. Diminished activity of the key antioxidant enzyme - SOD in the aneurysm wall, particularly in its inner layer, favours free radical generation, oxidative stress development and consequently intensive lipid peroxidation. This process affects structural changes of the aneurysm wall.