A PAF-acether antagonist (N 48740 RP/Rhône-Poulenc) and laser-induced thrombi in rat mesenteric vessels

N 48740 RP, a pyrrolo(1,2-c)thiazole derivative and platelet-activating factor inhibitor, was tested in a thrombosis model, in which thrombi are produced in small rat mesenteric vessels. A phase contrast system, based on a Leitz Orthoplan microscope, was used to visualize thrombus formation. Vascular lesions were produced with a Coherent CR-2 supergraphite ion laser (argon laser) in vessels of 25-35 microns diameter. The results show a dose-dependent (5-20 mg/kg i.v.) antithrombotic effect of N 48740 RP which reaches its maximum between 30 min and 2 h after the injection and slowly decreases during the following 24-48 h.