Behavior of platelets and leukocytes on the luminal surface of small caliber polyurethane grafts.

With scanning electron microscopy, we examined the behavior of platelets and leukocytes on the luminal surface of small caliber polyurethane grafts implanted into small arteries of dogs. Thirty-five grafts were implanted to the carotid and/or femoral arteries. The animals were treated with aspirin and/or DN9693, an inhibitor of phosphodiesterase. In the group treated with aspirin (40 mg/kg i.v.), the deposition of platelets on the luminal surface of the implanted polyurethane grafts was suppressed and the luminal surface was covered with adherent leukocytes. Fibrin nets were formed on the adherent leukocytes. In addition, the adhesion of leukocytes on the grafts was considerably suppressed in the group treated with DN9693 (50 micrograms/kg/min i.v.), and the formation of fibrin nets was markedly reduced. In contrast, in the control group the luminal surface was covered with numerous platelets and some leukocytes, which formed thrombi. These findings suggest that leukocytes adhere primarily to the prosthetic graft and play an important role in the initiation of fibrin formation.