Differences in tissue plasminogen activator activity and plasmin inhibition between newborn and adult rat.

Histochemically studied, the heart, spleen, liver, kidney cortex, lung, sciatic nerve, gastrocnemius muscle, skin and tongue showed a higher fibrinolytic activity (plasminogen activator activity) in the newborn than in the adult rat. I the medulla of the kidney the activity was slightly lower in the newborn than in the adult. The plasmin inhibition was lower in the newborn than in the adult rat in all organs studied.