The Role of Prostaglandins in Platelet-Vessel wall Interactions

Abstract

In an in vivo model developed for the study of arterial thrombosis in the white Wistarrat, it was demonstrated that superfusion of the investigated arterial segment with cyclo oxygenase inhibitors (ASA, indomethacin, flurbiprofen) resulted in a marked decrease of ADP-induced thrombosis while tranylcypromine enhanced the thrombotic phenomenon. As other MAO inhibitors were without effect, it was concluded that tranylcypromine possibly decrsibsed the PGE2-synthetase activity of the vessel wall. In the light of these findings we then suggested that the platel et-vessel wall interaction was dependent at least to some extent on the cyclic endoperoxides-PGI2 ratio of the endothelium and eventually of the deeper vascular structures. Electron microscopic studies on arterial segments used in our model revealed that suloctidil markedly decreases smooth muscle cell hypertrophy following local deendothelialization. Furthermore reconstitution of the endothelial lining consisting in endothelial cell hypertrophy and sliding over the dcendothelialized are until cell contact is made was also delayed. Following the intravenous administration of suloctidil (0.5 mg/kg) in our model the thrombus enhancing effect of locally superfused tranylcypromine was Offset. These experiments suggest that a decreased PGI2-synthetase activity is inhibited by a platelet function active drug such as suloctidil.

Coronary Vasoconstrictor and Vasodilator Actions of Arachidonic Acid in the Isolated Perfused Heart of the Rat

“…The TxA2-like synthetase could be selectively inhibited by Dpy, Spyz or low concentrations of ASA. These data do not preclude the importance of platelet synthesized TxA2 acting as a pro-aggregatory factor involved, for instance, in vascular injuries (Srivastava, 1978;Gorman, 1979;Bourgain, Andries & Finne, 1979). However, the vascular synthesis of TxA2 may further aggravate the compromised coronary flow by inducing vasoconstriction.…”

Animal Models in Radiotracer Design

“…There have been several different approaches to evaluate the platelet-endothelium interaction after an acute endothelial injury (Groves et aL, 1979;Ramirez et aI., 1981;Stemerman and Ross , 1972;Bourgain et al, 1979b;Dejana et aI. , 1980;Finkelstein et al , 1982).…”