Experimental endotoxemia increases plasma von Willebrand factor antigen concentrations in dogs with and without free-radical scavenger therapy.

Pentobarbital-anesthetized beagles were infused with physiologic saline (control dogs) or E. coli endotoxin (1.5 mg/kg i.v.) for 1 min. The plasma von Willebrand factor antigen (vWf:Ag) concentration, a potential index of endothelial damage, was monitored before and for 4 h after endotoxin challenge. The plasma vWf:Ag concentration increased only slightly in the control dogs (n = 6); whereas, in dogs infused with endotoxin (n = 20), the vWf:Ag concentration increased progressively to 2.1 times prechallenge values in 4 h. In addition to endotoxin, some of these dogs were treated with free-radical scavengers; allopurinol (n = 3), allopurinol plus superoxide dismutase and catalase (n = 6), or deferoxamine (n = 5). The free-radical scavengers did not prevent endotoxin-induced increases in vWf:Ag concentration.