Summary
Patients with hyperlipoproteinaemia or spontaneous thromboembolism, known to be poor
responders to DDAVP or to venous occlusion with regard to the rise in fibrinolytic
activity of the blood, appeared to show a normal increase in t-PA-antigen after the
same procedure. In their plasma a higher than normal level of free, fast-acting t-PA-inhibitor
was found as measured by titration with purified t-PA. This free t-PA-inhibitor level
only decreased after the test, in contrast to its complete disappearance in normal
responders. The same happened in a healthy volunteer who failed to exhibit a rise
in fibrinolytic activity after exhaustive exercise.
We suppose that the lack of response of the fibrinolytic activity in these cases is
due to a high inhibitor level and not to impaired release of t-PA into the blood.
In contrast, patients with terminal renal insufficiency showed only a slight increase
in t-PA-antigen after DDAVP. The level of free fast-acting inhibitor was normal in
most cases and did not change appreciably during DDAVP-infusion. In these patients,
a true impairment of the release of t-PA appears to exist.
Keywords
t-PA-inhibitor - Standard - DDAVP - Exercise - Venous occlusion
