Endotoxin elicits nitric oxide release in rat but prostacyclin synthesis in human and bovine vascular smooth muscle cells

Lipopolysaccharide (LPS) exposure to cells and tissues can mimic the biochemical events leading to septic shock. Previous data demonstrated a massive upregulation of prostaglandin endoperoxide H-2 synthase (PGHS-2), but not NO synthase-2 (NOS-2) in bovine smooth muscle cells (SMC) between 2 and 12 h of LPS exposure. This caused an abundant release of prostacyclin (PGI(2)) by constitutive PGI(2)-synthasc as a counterregulation to a dysfunctional endothelium. We here report that human as well as bovine SMC mainly respond by the induction of PGHS-2 and the subsequent release of PGI(2), whereas rat SMC exhibited a distinct induction of NOS-2 and released significantly higher amounts of NO compared with cattle and human. The induction of either PGHS-2 or NOS-2 in the three different species investigated seems to be mutually exclusive in the time window of 2-24 h. This finding should be considered in the setup of experimental models for the investigation of septic shock. (C) 2004 Elsevier Inc. All rights reserved.