Hemodynamic Effects of Bradykinin Antagonism in Porcine Gram-Negative Sepsis

Abstract

Activation of the kallikrein-kinin system in sepsis has long been recognized, but its role, beneficial or pathologic, has not been defined. Recently, however, specific bradykinin (BK) antagonists have become available and this study investigated the effects of a BK antagonist, NPC17731 (Scios-Nova) on systemic and pulmonary hemodynamics in a model of gram-negative sepsis. Anesthetized swine were studied for 5 h receiving a 1-h infusion of saline (controls, group 1, N = 8) or live Pseudomonas aeruginosa (septic, group 2, N = 8). Group 3 (treatment, N = 6) received NPC17731 (5 mg/kg initial bolus followed by 1 mg/kg hourly) just prior to the onset of sepsis. Group 2 animals showed a rapid decrease in systemic arterial pressure (SAP) from 30 min onward, and sustained significant hypotension from 2 h onward. In group 3, SAP fell similarly until 2 h then progressively rose, returning to baseline levels by 5 h. In contrast, cardiac index fell progressively from 3 h onward in groups 2 and 3. Systemic vascular resistance index (SVRI)fell significantly by 2 h in group 2 animals, recovering to baseline by 5 h. Group 3 showed a similar initial fall followed by a rebound increase in SVRI, which, at 5 h was significantly raised above the other groups. Group 2 developed significant, persistent pulmonary artery hypertension which was not reduced by NPC17731. The data imply a significant role for bradykinin in the pathogenesis of hypotension in septic shock in this model. Septic shock was reversed by a BK antagonist which increased peripheral resistance without affecting cardiac output. However, NPC17731 exerted no effect on the pulmonary circulation. BK antagonists my play a beneficial role in the armamentarium against septic shock.

Key Words:

• bradykinin
• hemodynamics
• sepsis