[Effect of multiple intravenous injections of heparin on the content of antithrombin III in healthy animals and experimental atherosclerosis].

Content of antithrombin III in blood was decreased by 30-40% as compared with the initial level after eight intravenous injections of heparin (40 IU/200 g of body mass) into healthy rats and into animals with experimental atherosclerosis. The maximal decrease of antithrombin III content was found within 30 min after the last administration of heparin in circulation. Normalization of the antithrombin III occurred within 1.5-4 hrs after the heparin administration. Decrease in the content of antithrombin III after the heparin administration was accompanied by elevation in total fibrinolytic activity and in nonenzymatic fibrinolysis, thus indicating apparently the transient formation of heparin-blood proteins complexes including antithrombin III.