A chemiluminescent detection of superoxide radical produced by adherent leucocytes to the subendothelium following thrombolysis: studies with a photochemically induced thrombosis model in the guinea pig femoral artery

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) because denuded vessel wall exposed to blood following thrombolysis is a favourable surface for platelet and leucocyte deposition. We have applied a chemiluminescence technique to detect superoxide radical (O2−) produced by leucocytes adherent to the femoral artery 24 h after photochemically induced thrombogenesis in the guinea pig in vivo and subsequent thrombolysis by rt-PA. Intravenous administration of MCLA, a specific chemiluminescence reagent for detecting O2−, markedly increased photon emission. The photon emission was markedly potentiated by phorbol myristate acetate and was suppressed by superoxide dismutase. Reocclusion 24 h after rt-PA induced thrombolysis was observed in 10 of 16 animals. Histological observations revealed extensive polymorphonuclear leucocytes adherent to the vessel wall at the site of thrombogenesis and thrombolysis. A higher level of O2− could be detected from the arteries in which thrombolysis was induced compared with those without thrombolysis. Further, the level of O2− detected was greater in reoccluded arteries compared with those in which reflow was established. These observations suggest that O2− is produced by adherent leucocytes at the site of thrombolysis and that leucocytes are involved in reocclusion after thrombolysis.