Abstract
It is generally recognized that Antithrombin III plays an important role as an inhibitor on the coagulation mechanism of the blood and is known to be decreased in its amount on the cases of myocardial infarction or arteriosclerosis, in the meanwhile the arteriosclerosis has been considered to be one of thrombogenic factors. This research was designed to investigate the effects of Antithrombin III on the relationship between thrombosis and atherosclerosis. For the purification of Antithrombin III, heat defibrinated plasma was applied to the column of heparin covalentry linked to Sepharose 4B. Non-specifically bound protein was eluted with 0.01M Tris HCl buffer pH 7.5 containing 0.3M NaCl and Antithrombin III subsequently eluted with 0.01M Tris HCl buffer containing 0.08M NaCl. Aliquots of each fractions were assayed for antithrombin activity. The highly purified Antithrombin III was obtained by this affinity chromatography with heparin as the legand. This inhibitor possessed both heparin cofactor and progressive antithrombin activity, and SDS disc electrophoresis showed only single band of molecular weight 62, 000 daltons and rabbit antiserum immunized with this fraction showed also single precipitation arc on IEP. The degree of lipolytic activity was measured by estimation of amount of the released free fatty acids according to the modified method of Boberg and Carlson. The incubation mixture contained various triglycerides as substrates and Antithrombin III as enzyme. The triglyceride substrate, Intralipid fat emulsions were hydrolyzed by the purified Antithrombin III to a certain extent and free fatty acids released were increased pararell with the incubation period and with Antithrombin III amount. The effects of Antithrombin III on the various triglyceride substrates were compared and the triglyceride moiety of these substrates were preferentially hydrolyzed in order of Intralipid, Triolein, Serum Chylomicron.
Atherosclerosis is one of the thrombogenic factors and has been considered to be due to the disorders of lipid metabolism on the vessel wall and also hyperlipemia is emphasized to be one of causative factors. On the other hand decreased antithrombin activity developes hypercoagulable state, which results in fibrin formation on the endothelial cells. Present data indicates that Antithrombin III with lipolytic activity could be postulated as an important inhibitor which intervenes between thrombosis and arteriosclerosis.
