For mice serum, abdominal artery blood samples from mice at
different time points were collected into heparinized plastic tubes,
upon oral administration of 0, 5, 10, 30 mg UPA of 1 kg healthy
mice. After placing them at 310 K water bath for 1 h, mice serum
samples were obtained after centrifuging the blood samples.
According to the method of Chen et al. [17], to eliminate protein,
1.0 mL of serum samples was placed in a 10 mL glass tube and
4.0 mL of acetonitrile was added. The mixture was shaken for 30 s
and centrifuged for 10 min at 3000 rpm. Finally the supernatant
was determined for UPA.