Our studies focused on the necessity of the immediate acidification for measuring the biological activity of tissue-plasminogen activator (t-PA) in the blood samples. The following results were obtained: 1. Biological Activity (BA) and immunological activity (IA) of t-PA increased after venous occlusion. However, the BA of t-PA was considerly lower in plasma than in the blood samples immediately acidified after venous puncture. 2. BA of t-PA in the blood decreased rapidly after sampling without acidification. 3. PAI activity in plasma correlated inversely to the specific activity of t-PA released venous occlustion.
In conclusion, when measuring the t-PA activity in the blood, immediate acidification is necessary to prevent its inactivation probably by PAT co-existing in the plasma.
