ULVWF, plasma VWF, and A1 domain samples displayed by gel electrophoresis.

(A) The histamine-stimulated endothelial cell supernatant contains ULVWF multimers (first lane). ULVWF multimers are absent in the plasma VWF sample (second lane). The VWF-to-antigen levels for ULVWF and plasma VWF were 15 U/dL and 100 U/dL, respectively. Analysis of ULVWF and plasma VWF was by sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis (12.5%) and chemiluminescence. (B) The first lane contains molecular weight markers. Under reducing (R) and nonreducing (NR) conditions, the VWF A1 domain exists as a 36-kd monomer (second and third lanes). The reducing agent was 2-mercaptoethanol. VWF A1 concentrations used were 100 and 200 μg/mL. Analysis of the A1 domain was by SDS-agarose (1%) electrophoresis and autoradiography.