Influence of isoproterenol (10−8, 10−6 M) on pial artery diameter in newborn pigs before (control), after photothrombotic injury (PTI), or treated with tPA (2 mg/kg iv), RBC-tPA (0.1 mg/kg iv), U 0126, SB 203580, SP 600125 or D-JNKI1 (all 1 mg/kg iv), n=5 A: pretreatment 30 before PTI B: post treatment 2h after PTI. Measurements were made at 2.5 h post PTI.