Inhibition by endothelial cells of platelet aggregating activity of thrombin--role of thrombomodulin.
Cultured human umbilical vein endothelial cells inhibited the platelet aggregating activity of thrombin in the absence of plasma. Using a new method in which thrombin-induced platelet aggregation was measured in the presence of endothelial cells, we showed that aspirin-treated endothelial cells inhibited platelet aggregating activity of thrombin in an incubation time- and cell number-dependent manner. This inhibitory effect of endothelial cells was partially blocked by the pretreatment of endothelial cells with monoclonal anti-thrombomodulin IgG (anti-TMIgG). It is suggested that (1) endothelial cells play a role in the clearance of thrombin by binding and inactivating this enzyme and that (2) thrombomodulin on endothelial cells, apart from its role for protein C activation, may be involved in this endothelial function.
Murata
M
M
Department of Haematology, Keio University, Tokyo, Japan.
Ikeda
Y
Y
Araki
Y
Y
Murakami
H
H
Sato
K
K
Yamamoto
M
M
Watanabe
K
K
Ando
Y
Y
Igawa
T
T
Maruyama
I
I
D001241:Aspirin / Q000494:pharmacology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D011464:Epoprostenol / Q000096:biosynthesis; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*; D011956:Receptors, Cell Surface / Q000502:physiology*; D018179:Receptors, Thrombin; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D011464:Epoprostenol; D013917:Thrombin; D001241:Aspirin