Role of the bradykinin B2 receptor for the local and systemic inflammatory response that follows severe reperfusion injury

1 Bradykinin (BK) appears to play an important role in the development and maintenance of inflammation. Here, we assessed the role of the BK B-2 receptor for the injuries that occur after ischemia and reperfusion (I/R) of the territory irrigated by the superior mesenteric artery. 2 Tissue (lung and duodenum) kallikrein activity increased after ischemia with greater enhancement after reperfusion. A selective inhibitor of tissue kallikrein, Phenylacetyl-Phe-Ser-Arg-N-(2,3-dinitrophenyl)-ethylenediamine (TKI, 0.001 - 10 mg ml(-1)), inhibited kallikrein activity in a concentration-dependent manner in vitro. In vivo, pretreatment with TKI (30 mg kg(-1)) prevented the extravasation of plasma and the recruitment of neutrophils. 3 Similarly, the bradykinin B-2 receptor antagonists, HOE 140 (0.01-1.0 mg kg(-1)) or FR173657 (10.0 mg kg(-1)), inhibited reperfusion-induced increases in vascular permeability and the recruitment of neutrophils in the intestine and lungs. 4 In a model of more severe I/R injury, HOE 140 (1.0mg kg(-1)) inhibited the increase in vascular permeability, neutrophil recruitment, haemorrhage and tissue pathology. Furthermore, HOE 140 significantly inhibited the elevations of TNF-alpha in tissue and serum and partially prevented lethality. This was associated with an increase in the concentrations of IL-10 in tissue and serum. 5 Thus, our results demonstrate that, following intestinal I/R injury, there is an increase in tissue kallikrein activity and activation of BK B-2 receptors. B-2 receptor activation is essential for the development of inflammatory tissue injury and lethality. These results contrast with those of others showing that BK mostly exerts a protective role during I/R injury.