Thrombin induces Contraction And increased 51-Cr Release from Cultured Human Endothelial Cells
Injury to human endothelial cells(EC) in primary culture was evaluated by a 51-Cr release assay, phase contrast microscopy and the trypan blue exclusion test. Normal integrity of EC, was maintained and 51-Cr release showed a slow linear increase during 24h incubation with either RPMI 1640 supplemented with 20% foetal calf serum, glutamine and antibiotics(SCM) or normal human serum(NHS). Thrombin in a concentration as low as 0.1 IU/ml induced obvious contraction of EC incubated in SCM, but the cells remained fixed to the bottom of the wells. Cell contraction was maximal after 15min and disappeared within 4h. 51-Cr release increased 2-3 fold within a few minutes and remained increased during an incubation period of 4h. The injurious effect of thrombin was inhibited in SCM containing hirudin(l.7 u/ml) or in NHS. ADP(10-5 M), endotoxin (0.1mg/ml) and 5 vasoactive agents adrenalin 5.5 10-5, noradrenalin 5.9 10-5 M, histamine 9.10-4 M, bradykinin 7.5 10-7 M and serotonin 10-5 M) did not cause cellular injury. Cultured human EC are injured by thrombin. The other tested agents do not appear to induce direct injury in vitro, but may interact with cellular elements in the blood to produce the endothelial injury previously observed in vivo.