REPERFUSION INDUCES SUBLETHAL ENDOTHELIAL INJURY

Background. Endothelial cells are pivotal in regulating thrombosis and hemostasis. In this study, we sought to characterize endothelial dysf unction and endothelial cell injury in vitro after hypoxia/ reoxygenat ion. Materials and methods. Cultured human umbilical vein endothelial cells (ECs) were exposed to 120 min of hypoxia followed by reoxygenati on. The release of thrombomodulin (TRI) and the production of prostagl andin I-2 (PGI(2)) were measured. Endothelial cell injury in hypoxia/r eoxygenation was measured by two assays, the Fura-a release assay and the (51)chromium (Cr-51) release assay. Results. TM release from ECs d uring normoxic incubation was undetectable, while it was slightly incr eased during hypoxic incubation. After reoxygenation, the release of T M increased, and it became significantly higher at 120 min after reoxy genation compared with hypoxic incubation. The production of PGI(2) si gnificantly decreased during hypoxic incubation and further decreased within 30 min after reoxygenation, but returned to normoxic levels at 120 min after reoxygenation. In the Fura-a release assay, a rapid and significantly greater release of Fura-2 was observed in hypoxia/reoxyg enation compared with hypoxic incubation. In the Cr-51 release assay w hich demonstrates cell death, Cr-51 release did not increase in hypoxi a/reoxygenation. Conclusions. The present study suggests that 120 min of hypoxia/reoxygenation induces endothelial dysfunction of ECs but do es not cause cell death. (C) 1998 Academic Press.