Protein plasma extravasation (PPE) in the right (inoculated) hemisphere of 6 different groups of animals. There was a significant increase in PPE when the 17-day-C6-injected animals were concomitantly injected with SAR 100 nm/Kg (C6 + SAR) compared to the control group (C6-inoculated). Vehicle-inoculated and vehicle-inoculated + SAR (100 nm/Kg) animals did not differ from each other or from the control. Bradykinin (100 nm/Kg) injected through the femoral vein did not enhance BTB permeability (C6 inoculated + BK). However, the specific bradykinin B1 antagonist, LEU (100 nm/Kg), improved SAR-induced PPE in the tumor mass (C6-inoculated + LEU + SAR). *p < 0.01 compared to PPE in the C6-inoculated, vehicle-inoculated, vehicle-inoculated + SAR, and C6 inoculated + BK groups and in the C6-inoculated+LEU+SAR group.