Influence of Factor VIII-VON Willebrand Factor on Platelet Adhesion to Human Artery Subendothelium in Pulsatile and Non-Pulsatile Flow

The influence of Factor VIII-Von Villebrand (F.VIII-VWF) on platelet adhesion to human post mortem artery subendothelium (SE) was studied in a perfusion chamber model according to Baumgartner, in pulsatile and non-pulsatile flow. Non-pulsatile flow was obtained by means of gravity while the perfusate was recirculated under similar conditions as in the pulsatile flow system. Platelet adhesion was greater in non-pulsatile flow than in pulsatile flow. A physiological amount of F.VIII-VWF increased the platelet adhesion approximately two-fold in both systems. When different concentrations of purified F.VIII-VWF were added to perfusates with this plasma factor, smaller concentrations corrected the adhesion in non-pulsatile flow than in pulsatile flow. Perfusates without F.VIII-VWF containing platelets suspended in red cells and plasma-cryosupernatant/Von Willebrand plasma/human albumin solution (HAS)or dextran solution resulted in the same amount of adhesion. When purified F.VIII-VWF was added to these perfusates, the adhesion increased to the level obtained in normal plasma and hemophilic plasma., Thus F.VIII-VWF is the only plasma protein necessary for normal platelet adhesion to SE. ¹²⁵J-F.VIII-VWF was found to bind to SE before the F.VIII-VWR facilitated adhesion occurred. Binding of ¹²⁵J-FVIU-VWF to SE was similar in pulsatile and non-pulsatile flow. However less bound ¹²⁵J-FVIII-VWF was needed to increase platelet adhesion in non-pulsatile flow than in pulsatile flow.