Stimulation of Endothelial Cell Prostacyclin Production by Thrombin, Trypsin, and the Ionophore A 23187

Babette B. Weksler; Christopher W. Ley; Eric A. Jaffe

doi:10.1172/JCI109220

Stimulation of Endothelial Cell Prostacyclin Production by Thrombin, Trypsin, and the Ionophore A 23187

Babette B. Weksler, Christopher W. Ley, and Eric A. Jaffe

Published November 1, 1978 - More info

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Abstract

Prostacyclin (PGI₂) is an unstable prostaglandin which inhibits platelet aggregation and serotonin release and causes vasodilation. The PGI₂ activity produced by monolayers of cultured human endothelial cells and fibroblasts was measured by the ability of their supernates to inhibit platelet aggregation in platelet-rich plasma, or to inhibit thrombin-induced [¹⁴C]serotonin release from aspirin-treated, washed platelet suspensions. Monolayers of cultured human endothelial cells, stimulated with sodium arachidonate, thrombin, the ionophore A 23187, or trypsin, secreted PGI₂ into the supernatant medium. Monolayers of fibroblasts produced PGI₂ activity only when stimulated by arachidonate. “Resting,” intact monolayers did not produce detectable PGI₂, nor did monolayers treated with ADP or epinephrine. Production of PGI₂ activity was abolished by treatment of the monolayers with indomethacin, tranylcypromine, or 15-hydroperoxy arachidonic acid. The PGI₂ activity of the supernates was destroyed by boiling or acidification. Inhibition of thrombin with diisopropylfluoro-phosphate, and of trypsin with soybean trypsin inhibitor, abolished the stimulation of PGI₂ production by these enzymes. Production of thrombin at a site of vascular injury could, by stimulating PGI₂ synthesis by endothelial cells adjacent to the injured area, limit the number of platelets involved in the primary hemostatic response and help to localize thrombus formation.