Aspirin prevents Escherichia coli lipopolysaccharide- and Staphylococcus aureus-induced downregulation of endothelial nitric oxide synthase expression in guinea pig pericardial tissue.

The aim was to analyze whether pericardial tissue expresses endothelial NO synthase (eNOS) protein and to determine the presence of cytosolic proteins that bind to eNOS mRNA. The effect of aspirin on the above-mentioned parameters was also analyzed. eNOS protein was expressed in pericardial tissue from male guinea pigs. Escherichia coli lipopolysaccharide (LPS, 10 microgram/mL) and Staphylococcus aureus endotoxin (SA, 10 microgram/mL) reduced eNOS protein expression and shortened the half-life of the eNOS messenger. Under basal conditions, cytosolic extracts from pericardial samples bound to the 3'-untranslated region (3'-UTR) of eNOS mRNA, which was enhanced by LPS and SA. Proteinase K fully prevented the binding of cytosolic pericardial extracts to 3'-UTR of eNOS mRNA, suggesting the involvement of proteins that were further characterized as 60- and 51-kDa proteins. Aspirin (1 to 10 mmol/L) restored eNOS expression in either LPS- and SA-stimulated pericardial samples and reduced the binding activity of the pericardial cytosolic proteins to 3'-UTR of eNOS mRNA. Indomethacin also reduced the downregulation of eNOS by LPS and diminished the binding activity of the cytosolic proteins, although higher doses of indomethacin than of aspirin were needed to improve these parameters. In conclusion, eNOS protein is expressed in guinea pig pericardial tissue. LPS and SA stimulate the binding activity of pericardial cytosolic proteins to 3'-UTR of eNOS mRNA and reduce eNOS protein expression. High doses of aspirin and indomethacin protect eNOS protein expression and reduce the binding activity of the cytosolic proteins to 3'-UTR of eNOS mRNA, suggesting an inverse association between the presence of these cytosolic proteins and eNOS expression.

[Effect of HMG-CoA reductase inhibition on endothelial dysfunction-inducing protein in hypercholesterolemic rabbits]. / Efecto de la inhibición de la HMG-CoA reductasa sobre la proteína inductora de disfuncion endotelial en conejos hipercolesterolémicos.

INTRODUCTION AND OBJECTIVES: In our laboratory, we recently obtained evidence that cultured bovine endothelial cells contain cytosolic proteins that form complexes with the 3'-unstranslated region of endothelial nitric oxide synthase (eNOS) mRNA and are associated with its destabilization. The aim of this study was to determine the presence of such proteins and the level of eNOS expression in hypercholesterolemic rabbits as an in vivo model of endothelial dysfunction. METHODS AND RESULTS: Endothelium-dependent relaxation in response to acetylcholine was reduced in aortic segments from hypercholesterolemic rabbits compared with controls. Treatment of hypercholesterolemic rabbits with simvastatin (25 mg/kg body weight/day) restored endothelium-dependent relaxation. Aortic eNOS expression was reduced in hypercholesterolemic rabbits and was accompanied by enhanced binding activity of a 60-KDa cytosolic protein and reduced stability of eNOS mRNA. Simvastatin treatment upregulated eNOS expression and reduced the interaction of cytosolic protein with the 3'-untranslated region of eNOS mRNA. CONCLUSIONS: These results demonstrate the presence of a 60-KDa protein that binds to eNOS mRNA and reduces eNOS expression in the vascular wall.

Sevoflurane reduces endothelium-dependent vasorelaxation: role of superoxide anion and endothelin.

PURPOSE: There are several reports suggesting that volatile anesthetics alter vascular endothelial function. We analyzed the effect of sevoflurane, a fluorinated volatile anesthetic, on nitric oxide (NO)-dependent relaxation, evaluating the role of the endothelium-derived vasoconstrictor endothelin-1 (ET-1). METHODS: The experiments were performed in rat isolated aortic segments aerated in the absence and in the presence of sevoflurane (2%). RESULTS: Acetylcholine-induced relaxation was reduced in aortic segments aerated with sevoflurane. Sevoflurane failed to modify relaxation in response to an exogenous NO donor, sodium nitroprusside. Superoxide dismutase, a scavenger of superoxide anion, partially restored the impaired vasorelaxation induced by sevoflurane, an effect that was associated with the release of superoxide anion. The presence of BQ-123, an antagonist of endothelin ETA-type receptors, normalized the vasorelaxing response to acetylcholine in the presence of sevoflurane. In addition, BQ-123 also reduced the ability of the sevoflurane-incubated vascular wall to release superoxide anion. CONCLUSIONS: Our results suggest that sevoflurane impairs the endothelium-dependent vasorelaxation but that the endothelium-independent response remains intact. ET-1 and superoxide anion are involved in the endothelial dysfunction induced by sevoflurane. Further studies are needed to associate the endothelial dysfunction related to sevoflurane shown herein and its reported preconditioning properties on the myocardium.

Expression of endothelial nitric oxide synthase in human peritoneal tissue: regulation by Escherichia coli lipopolysaccharide.

Changes in the expression of endothelial nitric oxide synthase (eNOS) in the peritoneum could be involved in the peritoneal dysfunction associated with peritoneal inflammation. Demonstrated recently in bovine endothelial cells was the existence of cytosolic proteins that bind to the 3'-untranslated region (3'-UTR) of eNOS mRNA and could be implicated in eNOS mRNA stabilization. The present work demonstrates that eNOS protein is expressed in human endothelial and mesothelial peritoneal cells. Escherichia coli lipopolysaccharide shortened the half-life of eNOS message, reducing eNOS protein expression in peritoneal mesothelial and endothelial cells. Moreover, under basal conditions, human peritoneal samples expressed cytosolic proteins that bind to the 3'-UTR of eNOS mRNA. The cytosolic proteins that directly bind to 3'-UTR were identified as a 60-kD protein. After incubation of human peritoneal samples with lipopolysaccharide, the binding activity of the cytosolic 60-kD protein increased in a time-dependent manner. Studies are now necessary to determine the involvement of this 60-kD protein in the regulation of eNOS expression in peritoneal cells and particularly its involvement in the peritoneal dysfunction associated with inflammatory reactions.