J. Biol. Chem., Vol. 255, Issue 17, 8031-8034, Sep, 1980
Evidence that the effects of thrombin on arachidonate metabolism in cultured human endothelial cells are not mediated by a high affinity receptor
P Lollar and WG Owen
The effect of thrombin and its derivative, diisopropylphosphoryl- thrombin
on [3H]arachidonic acid metabolism is studied in cultured umbilical vein
endothelial cell monolayers. Thrombin causes a dose- dependent release of
radioactivity from endothelial cells fed [3H]arachidonate. Thin layer
radiochromatography of acidified supernatants reveals that most of the
radio-activity is [3H]arachidonate and its metabolites, 6-ketoprostaglandin
F1 alpha and prostaglandin E2. Diisopropylphosphoryl-thrombin, which is
enzymatically inactive, does not cause release of arachidonic acid or
metabolites. A 50-fold excess of diisopropylphosphoryl-thrombin, despite
causing 98% inhibition of binding of 125I-thrombin to its high affinity
binding sites, does not inhibit thrombin-induced release. We conclude that
the high affinity, active site-independent thrombin binding sites are not
involved in thrombin-induced mobilization of esterified arachidonic acid.