Activation of fibrinolysis during xenoperfusion

Ten rabbit kidneys were perfused at 80 mm Hg, 37 degrees C, with oxygenated recirculating heparinized human blood. These experiments were compared to another ten perfusion experiments where 1 unit/ml porcine plasmin was added to the human blood one hour before the perfusion, at which time the fibrinolytic activity was significant and the fibrinogen concentration under the detection limit. Rejection, determined as time until blood flow decreased to 2 ml/min, was not significantly delayed by addition of plasmin. At the end of the experiments, the fibrinolytic activity in the control experiment had increased above the activity in the plasmin added experiments, although the fibrinogen concentration was almost unchanged. Histological examinations demonstrated a decreased platelet deposition and the fall in platelet count was smaller in the plasmin experiments. C3d determinations revealed a slight activation of complement upon addition of plasmin, but the activation by xenoperfusion was much more pronounced and, at the end of the experiment, the C3d concentration was the same in the two groups.