RESUMO
The presence of metalloproteinases in etherosclerotic plaques has been described but their role is not well understood. An increased secretion of these proteolytic enzymes could explain plaque instability and distal embolization. Plaque were divided in 1 segment with and 1 segement without stenosis, the latter being used as control. Both segments were incubated in culture media for 48 h or were fixed for histology. The conditioned medium was studied using gelatin zimography and digital densitometry. Melloproteinases were identified by their molecular weight, inhibition with EDTA or Western blot. Standard histologic study and immunohistochemistry were done. In stenotic areas, metalloproteinase 9 (92kD) secretion was 269 percent higher than in regular plaques (191 and 73 kilopixels/ug protein respectively p<0.02). The histological study of stenotic areas showed macrophage infiltration and neoformation of blood vessels. The increased secretion of cellular matrix degrading enzyme metalloproteinase 9 in stenotic areas of atherosclerotic plaques could axplain plaque instability and subsequent embolization