Peptide kinins are potent vasoactive agents in the microcirculation that might be released after burn injury. The present study was designed to test the hypothesis that Icatibant (JE 049), a potent, selective peptidomimetic bradykinin-B2 receptor antagonist, would reduce the cardiovascular pathology occurring in sheep exposed to 40% total body surface area (TBSA), third-degree burn. Female sheep were surgically prepared for chronic study. After 5 to 7 days' recovery from the operative procedure, they were randomized to five groups: sham (n = 6, noninjured, nontreated), medicated sham (n = 4, noninjured, treated with 20 mug kg h Icatibant), control (n = 7, 40% TBSA third-degree burn, nontreated), Icatibant-4 (n = 6, 40% TBSA third-degree burn, treated with 4 mug kg h Icatibant [low dose]), Icatibant-20 (n = 8, 40% TBSA third-degree burn, treated with 20 mug kg h Icatibant [high dose]). Prefemoral lymph flow (milliliters per hour) remained constant in the sham and medicated sham groups but increased after injury: control (0 h, 3.9 +/- 0.5; 24 h, 28 +/- 4.2; 48 h, 33.0 +/- 8.1). The increased fluid flux was associated with enhanced protein flux. Both low and high doses of Icatibant significantly reduced the microvascular fluid flux: Icatibant-4 (0 h, 5.3 +/- 0.6; 24 h, 17.5 +/- 3.5; 48 h, 20.3 +/- 3.4); Icatibant-20 (0 h, 5.3 +/- 1.1; 24 h, 15.2 +/- 2; 48 h, 17.6 +/- 4.1). Total prefemoral protein leak was reduced in all treatment groups. The low dose of Icatibant significantly reduced prefemoral lymph flow without adversely affecting the hemodynamic changes observed after burn injury in sheep, suggesting that the bradykinin antagonist would reduce edema formation and improve fluid management of thermally injured patients.