THROMBOSIS RESEARCH 69; 101-l 1111993 0049-3848/93 $6.00 + .OOPrinted in the USA. Copyright (c) 1993 Pergamon Press Ltd. All rights reserved. FREE RADICAL SCAVENGING MEXHANISMS DURING PULMONARY THROMBOEMBOLISM IN RATS* R. Kumari, M. Dikshit and R. C. Srimal Division of Pharmacology Central Drug Research Institute Lucknow - 226001, INDIA (Received 16.6.1992; accepted in revised form 31 .10.1992 by Editor G.G. Neri Serneri) ABSTRACT In the present investigation alterations in the free radical generating and scavenging enzymes * platelets, neutrophils (PMNLs), heart and zyxwvutsrqponml ,UZj homogenates following rat pulmonary thromboemboliam have been studied. Thrombosis was induced by intravenous infusion of collagen and adrenaline. Levels of malonaldehyde (MDA) were elevated in the PMNLS after thrombosis. Activities of superoxide dismutase (SOD) and catalase (CAT) were found to increase in platelets and PMNLS respectively. However, there was no significant alteration in the lactate dehydrogenase (LDH), lysozyme (LYS), ratio of xanthine oxidase to dehydrogenase (XO/XH) and PMNLs :g- generation before and after thrombosis. Migration PMNLS following thrombosis was indicated by increased activity of myeloperoxidase (MPO) in the heart. In addition, pretreatment with allopurinol, a xanthine oxidase inhibitor and indomethacin, a cyclooxygenase inhibitor offered protection against thromboembolism induced death/paralysis. Results suggest the involvement of free radicals in thrombosis. Free radicals are the most reactive chemical species and are implicated in several type of pathological states (1,2). Their involvement in pulmonary thromboembolism has been reported in earlier communications from this laboratory (3-6). It has been demonstrated that thrombosis induced by intravenous collagen and Key.words: Pulmonary thromboembolism, malonaldehyde,catalase superoxide dismutase, myeloperoxidase, lysozyme and xanthine oxidase. *CDRI Communication No. 4993 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH 101