The expression of the von Willebrand factor (vWF) gene by cultured endothelial cells from the porcine pulmonary artery, aorta, and lung was cornpared at the levels of messenger (m)RNA and antigen. Steady-state levels of vWF mRNA were determined by di)t-k)lot analysis using a partial human vWF cDNA as the hybridization probe; vWF mKNA from cultured aortic endothelial cells, and v w r antigen secreted into the culture supernatants were barely detectable. In contrast, vWF mRNA and antigen from the pulmonary artery endothcliai cell5 were approximately eight to nine tirnes that demonstrated by aortic-w l l s . Levels of vWF rnKNA and antigen in cultured lung cells were intermediate of thosc found in the pulmonary artery and aorta and corrrlatcd with thc estimated number of cells demonstrated to be of endothelial origin in the mixed cell populations grown from the lung. Differences between the levels of vWF inKNA found in cultured cells from the pulmonary artery and thnsr found in the aorta were maintained in cells processed directly from these vessels. Correlation between the levels of vWF mKNA ,ind antigen in endothelial cells from different vessels of the pig suggests that the differential control of vWF synthesis is at the level of transcription. Furthermore, maintenance in cultured cells of the difference in transcription rates that were observed in vivo suggests that vWF gene exprcssion is not exclusively regulated through environmental factors.