PROTECTIVE EFFECTS OF WEB-2086 (PAF ANTAGONIST) AND KETOPROFEN (NSAID) ON PAF-INDUCED CHANGES IN THE MORPHOLOGICAL ULTRASTRUCTURE OF BLOOD-PLATELETS IN CALVES

The ultrastructure of bovine platelets was examined by transmission el ectron microscopy without any pretreatment (control), and after WEB 20 86 (a triazolodiazepine) or ketoprofen (NSAID) pretreatment, followed by PAF infusion. The blood platelet count was also investigated. The g roup of calves that received WEB 2086 pretreatment before platelet-act ivating factor (PAF) infusion did not show a decreased number of plate lets. However, in the other group, with ketoprofen pretreatment before PAF infusion, there was a rapid decrease From 1 to 3 min, while from 5 min the number of platelets recovered to the normal value. Electron microscopy revealed that pretreatment with WEB 2086 followed by PAF in fusion did not alter the morphological ultrastructure of bovine platel ets, except that the microtubules were briefly modified From 1 until 3 min after PAF challenge. After ketoprofen pretreatment, bovine platel ets kept their regular shape, the number of dense bodies was not signi ficantly altered, the number of mitochondria was maintained From 5 min after PAF infusion, giant platelets were not observed and the Golgi a pparatus was rarely visible. Thus pretreatment with WEB 2086 and ketop rofen before PAF infusion had a protective activity on the ultrastruct ure of bovine platelets and, in cattle, pretreatment with WEB 2086 and ketoprofen before PAF challenge prevented the thrombocytopenia induce d by PAF.