Studies on Antithrombin Activity in the Human Aortic Intima, with Special Reference to its Correlation to Atherosclerotic Changes
Authors: Yukio Tsubokawa
Journal: Circulation (1970)

Since what is called thrombogenic theory was established by DUGUID, blood coagulation mechanism has been considered to take a part in pathogenesis of atherosclerosis. Later, it became clear that not only a strong thromboplastic activity but also anticoagulant activity existed in the aortic intimas. As to the anticoagulant activity of the vascular walls, KIRK et al. have pointed out that some of acid mucopolysaccharides (AMPS) in human aortic walls have a function of anticoagulant activity. Very recently OHE of our laboratory described originally the presence of antithrombin activity in aortic intimas of pigs. This is of intermedate type and has an activity derectly to inactivated thrombin. Purpose of the present experiments was to know a nature of intimal antithrombin of human aortas and correlation between the activity and variable atherosclerotic lesions of the aortas, ageing of the patient and amount of metachromatic materials in the human aortic intimas. Materials and Methods About 130 cases of fresh human aortic intimas were used as materials. Selerosing grade of human aortas was classified into 4 groups, as shown in Table I. By means of Endothelial Membrane Method (EMD), described by OHE, aortic intimal extracts were prepared from each group of the intimal lesions. Differential centrifugation of homogenates of each layers of the aortas, in particular of each of different sclerotic lesions of the intimas was made for test of antithrombin activity. Sephadex G-100 gel filtration of aortic intimal supernatants obtained by 105, 000G centrifugation was performed for the purpose of purification of antithrombin activity. Blood coagulation tests were performed in following method: plasma clotting activity (Fig. 1), thromboplastin generation test (Fig. 2), antithrombin activity test to use thrombin-fibrinogen system (Fig. 3, and Fig. 9) and TAMe system (Fig. 8) and so on. Histological examination of the aortic walls was made to use conventional staining method and OHNO's toluidin blue metachromasia method for detection of vascular AMPS. Results Plasma clotting time of aortic intimal extracts, obtained from many intact intimas by means of EMD, was found to be much longer than that of control solution. On the other hand, in cases of sclerotic intimas of grade I and II plasma clotting activity was significantly shortened with a parallelism to severity of atheroscletosis. It was also found that thromboplastin generation activity of the extracts from severe sclerotic intimas of grade II was as high as that of cephalin used routinely, intimal extracts from intact intimas, however, showed clearly inhibition of thromboplastin gene-ration activity. These facts suggested that sclerotic intimas may release substances rich in pro-coagulant activity rather than in anticoagulant activity into the blood. And in intact intimas the reverse may be also true. When antithrombin activity of the extracts from intact intimas was measured by means of two-stage method of thrombin-fibrinogen system. Characteristic developmental pattern of the activity was obtained and refered to as intermediate type of antithrombin (Fig. 3).