Competition between plasminogen and tissue plasminogen activator for cellular binding sites.

Cellular receptors for plasminogen and tissue plasminogen activator (t-PA) regulate plasminogen activation and cell-associated proteolytic activity. The characteristics of the interactions of both ligands with monocytes and monocytoid cell lines bear certain similarities, including affinity (kd approximately 1 mumol/L) capacity and susceptibility to carboxypeptidase treatment. Therefore, we have undertaken the present study to determine directly whether t-PA and plasminogen share common binding sites on cells.

Effects of linoleic and oleic acid anilides on prostacyclin synthesis and fibrinolytic profile of human endothelial cells in culture: relevance to the toxic oil syndrome.

We evaluated the effects of fatty-acid anilides (FAA) on prostacyclin (PGI2) synthesis and on the fibrinolytic properties of human umbilical vein endothelial cells. Preincubation of endothelial cells with oleic- and linoleic-anilides (OAA and LAA, respectively) resulted in a time- and concentration-dependent inhibition of ionophore A23187- and thrombin-induced PGI2 synthesis. However, no significant effects of FAA on arachidonic acid-induced PGI2 synthesis were found, except with 1000 microM LAA which inhibited cyclooxygenase activity after 24 h.

Binding of tissue plasminogen activator to human monocytes and monocytoid cells.

Monocytes and monocytoid cell lines previously have been shown to express receptors for plasminogen and urokinase (u-PA). In the present study, the monocytoid cell lines, U937 and THP-1, are shown to bind tissue plasminogen activator (t-PA) in a specific, saturable, and reversible manner. These cells bound t-PA with low affinity (kd = 0.