Abstract
In disseminated intravascular coagulation, tissue thromboplastin (T. Tbp) plays a great role as one of the direct trigger substances.
Attempts were made to demonstrate the coagulation-fibrinolytic changes and ultrastructural changes of the lung after the injection of T. Tbp.
T. Tbp was injected into pigs and blood samples were taken 10sec, 1min and 5min after the start of the injection. Ten sec after the injection, APTT and TEG-r shortened and fibrinopeptide A increased remarkably. One min after the injection, whole plasmin activity increased and antiplasmin decreased. Thus, it was suggested that fibrin deposition in pulmonary capillaries were induced by the action of thrombin on fibrinogen.
Then, the lungs of rabbits were examined by electron microscope. In the lung of suddenly died rabbit after the injection, capillaries were filled with plate-lets and fibrins. Endothelial cells were damaged and interstitial tissues were edematous. Twenty four hrs after the injection, endothelial cells were damaged, but no fibrin fibers were seen. In the lungs of rabbits injected with T. Tbp once a week for weeks, endothelial cells were strongly damaged and thrombi composed of platelets and fibrins were observed. Interstitial tissues were edematous and lamellar inclusion bodies of type B alveolar epithelial cells were lost.
As explained above, the injection of T. Tbp brought remarkable injuries in pulmonary capillaries and surrounding tissues, causing pulmonary microthromboembolism.
