Compliance with treatment. Ex vivo clot lysis time was used to assess the presence of both PTI and tPA administered to rabbits. Lysis times were determined in duplicate for 6 rabbits treated with Sal/Sal (□), 5 rabbits treated with Sal/PTI (▪), 4 rabbits treated with tPA/Sal (○), and 4 rabbits treated with tPA/PTI (•). Lysis time is reduced to approximately 40 minutes after the administration of PTI to the rabbit at 30 minutes. Subsequent administration of tPA, at 35 minutes, induces a reduction in lysis time to approximately 10 minutes. Each point reflects either 8, 10, or 12 individual measurements, in which the standard error of the mean is less than 10% of the indicated lysis time.