title: Disruption of COX-2 and eNOS does not confer protection from cardiovascular failure in lipopolysaccharide-treated conscious mice and isolated vascular rings.
abstract: It was hypothesized that a serial stimulation of vascular cyclooxygenase-2 (COX-2) with subsequent activation of endothelial nitric oxide synthase (eNOS) is responsible for decrease in blood pressure, cardiac performance, and vascular reactivity in endotoxemia caused by LPS. The hypothesis was tested in catheterized, conscious, freely moving, wild-type mice and mice (C57BL/6J background) with targeted deletion of COX-2 and eNOS that were given an intravenous LPS bolus (2 mg/kg, 055:B5). In vitro studies were performed on murine aorta rings. LPS caused a concomitant decrease in mean arterial blood pressure (MAP) and heart rate (HR) that was significant after 3 h and was sustained throughout the experiment (8 h). The LPS-induced changes in MAP and HR were not different from control in COX-2(-/-) and eNOS(-/-) mice. A prostacyclin receptor antagonist (BR5064) blocked the hypotensive effect of a prostacyclin agonist (beraprost), but did not attenuate the LPS-induced decrease in MAP and HR. LPS decreased eNOS and neuronal NOS mRNA abundances in several organs, while inducible NOS mRNA was enhanced. In aortic rings, LPS suppressed α(1)-adrenoceptor-mediated vascular tone. Inhibition of COX-2 activity (NS 398), disruption of COX-2, endothelium removal, or eNOS deletion (eNOS(-/-)) did not improve vascular reactivity after LPS, while the NO synthase blockers 1400W and N(G)-nitro-l-arginine methyl ester prevented loss of tone. COX-2 and eNOS activities are not necessary for LPS-induced decreases in blood pressure, heart rate, and vascular reactivity. Inducible NOS activity appears crucial. COX-2 and eNOS are not obvious therapeutic targets for cardiovascular rescue during gram-negative endotoxemic shock.
authors.affiliation: Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Stæhr
authors.forename: Kirsten
authors.initials: K
authors.lastname: Madsen
authors.forename: Paul M
authors.initials: PM
authors.lastname: Vanhoutte
authors.forename: Pernille B
authors.initials: PB
authors.lastname: Hansen
authors.forename: Boye L
authors.initials: BL
authors.lastname: Jensen
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D011464:Epoprostenol / Q000031:analogs & derivatives / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology; D006333:Heart Failure / Q000139:chemically induced*; D006339:Heart Rate / Q000187:drug effects; D008070:Lipopolysaccharides / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000235:genetics / Q000378:metabolism; D044006:Receptors, Epoprostenol / Q000037:antagonists & inhibitors; D013997:Time Factors
chemical_list: D008070:Lipopolysaccharides; D011941:Receptors, Adrenergic; D044006:Receptors, Epoprostenol; C048081:beraprost; D012313:RNA; D011464:Epoprostenol; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2