LIPOPOLYSACCHARIDE ACTIVATES ENDOTHELIAL NITRIC-OXIDE SYNTHASE THROUGH PROTEIN-TYROSINE KINASE

Vascular endothelial cell injury or activation by lipopolysaccharide ( LPS) plays an important role in the pathogenesis of endotoxin shock. H owever, the effect of LPS on NO production from vascular endothelial c ells (ECs) is incompletely understood. In this study, bovine coronary venular ECs were treated with LPS and the release of NO and expression of the endothelial NO synthase (ecNOS) were examined. We found that t he ecNOS activity is transiently enhanced by LPS within the time scale of about 10 h due to the interplay between two LPS-induced mechanisms . Within the first 10 h of LPS treatment, the specific activity of ecN OS is increased by a post-translational modification mediated through a protein tyrosine kinase cascade, After about 10 h of treatment, howe ver, LPS destabilizes the transcript of ecNOS and thus decreased the e xpression level and total activity. (C) 1998 Academic Press.