Objective: To determine whether endothelial cell (EC) von Willebrand factor (vWf) is uniformly distributed in canine blood vessels.
Design: Contents of EC vWf from vascular segments was evaluated in Haütchen preparations, using immuno-histochemistry. EC from femoral arteries and veins and jugular veins were grown in culture, and the intracellular content and constitutive release of vWf from these cells were measured. The amount of vWf mRNA in the cultured EC was determined.
Animals: Vascular segments for Häutchen preparations and EC for culture were obtained from 5 and 10 clinically normal, mixed-breed dogs, respectively.
Procedures: Appropriate vascular segments were removed, fixed; processed for immunohistochemistry, using a monospecific polyclonal antibody to canine vWf, and Haütchen preparations were made. Intracellular and constitutive released vWf was measured, using an ELISA, and vWf mRNA was measured by Northern blot analysis.
Results: Intact endothelial linings from femoral veins, jugular veins, vena cava, and pulmonary veins stained more intensely than femoral arteries, carotid arteries, aorta, and pulmonary veins. Constitutive release and intracellular content of vWf in cultured EC from femoral veins was about 30 times higher than that from femoral arterial EC, which was barely detectable. Similar differences were seen in amounts of mRNA.
Conclusions: There is marked diversity in EC vWf in canine vasculature that may result from differences in vWf mRNA.
Clinical relevance: Low amounts of vWf in canine systemic arterial EC may contribute to thromboresistance of canine arteries.