Endothelium-derived kinins account for the immediate response of endothelial cells to bacterial lipopolysaccharide.

We have recently shown that cultured endothelial cells produce kinins that can stimulate endothelial nitric oxide (NO) production in an autocrine manner. Because both the kallikrein-kinin system and the L-arginine/NO pathway have been implicated in the pathogenesis of septic shock, we investigated the possible involvement of endothelium-derived kinins in the response of cultured endothelial cells to bacterial lipopolysaccharide (LPS). In primary cultures of human umbilical vein and porcine aortic endothelial cells, LPS (0.3 to 3 micrograms/ml) induced significant concentration-dependent increases in cyclic GMP and 6-keto-PGF1 alpha, both of which were abolished in the presence of the selective bradykinin B2-receptor antagonist HOE 140 (0.1 microM). These LPS-induced increases in cyclic GMP and 6-keto-PGF1 alpha were short lived, being maximal after 5 min but were not apparent after 60 min. In parallel with these effects, LPS (30 micrograms/ml) induced a distinct, HOE 140-sensitive increase in the intracellular calcium concentration of human endothelial cells loaded with indo-1. In summary, these data suggest that the release of endothelium-derived kinin and subsequent stimulation of endothelial cells, followed by the enhanced production of NO and prostacyclin (PGI2), are implicated in the immediate hypotension induced by LPS in vivo.