Net release rates of total and active t-PA during stepwise intrabrachial artery infusions of DDAVP (0.7 to 7 to 70 ng/min for 5 to 5 to 15 minutes; ▪) and placebo (saline; ○) in 7 healthy male subjects. Means and SEM error bars. Both total and active t-PA increased significantly in response to DDAVP (ANOVA, time × treatment interaction: P < .0001).