title: LPS abolishes extrasplenic vasoconstriction to atrial natriuretic peptide: the role of NO and endothelin 1.
abstract: Sepsis causes changes in vascular resistance and hypovolemia. Previous studies have demonstrated that the spleen regulates blood volume via atrial natiuretic peptide (ANP). We hypothesized that LPS alters extrasplenic responses to ANP via endothelial-dependent mechanisms and studied the role of NO and endothelin 1 (ET-1). Isolated extrasplenic arteries and veins (vessels in mesentery adjoining spleen) were obtained from male Wistar rats weighing 200 to 280 g (n = 102) and mounted on a pressure myograph to determine intraluminal diameter for 4 h. Isolated vessels constricted in response to the half-maximum response of ANP (veins, 30% +/- 1.7%; arteries, 34.5 +/- 1.7%; P < 0.05), and this was abolished by the NO donor S-nitroso-N-acetylpenicillamine (SNAP 75 microM). Arteries and veins incubated with LPS (50 microg mL(-1) for 4 h) were unresponsive to ANP, and constriction was not restored by the NOS inhibitor N omega-nitro-L-arginine methyl ester (L-NAME 100 microM). However, venular constriction returned in the presence of the ET-1 antagonist Bosentan, increasing from -1.5 +/- 1.2 (10 min) to -10 +/- 2.5% (4 h) with LPS + Bosentan (3 x 10(-6) M) compared with -2.3 +/- 1.2 and 0% with LPS alone. In conclusion, LPS abolished endothelial-dependent extrasplenic venular constriction to ANP partially due to increased ET-1, whereas NO seemed to modulate vascular responses to ANP.
authors: Academic Unit of Anaesthesia, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom.
authors: Arnaud
authors: A
authors: Mansart
authors: Jonathan J
authors: JJ
authors: Ross
authors: Charles S
authors: CS
authors: Reilly
authors: Nicola J
authors: NJ
authors: Brown
authors: Zoë L S
authors: ZL
authors: Brookes
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001158:Arteries / Q000378:metabolism / Q000503:physiopathology; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001810:Blood Volume / Q000187:drug effects; D000077300:Bosentan; D019332:Endothelin-1 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020896:Hypovolemia / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D008643:Mesentery / Q000378:metabolism / Q000503:physiopathology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018805:Sepsis / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D013154:Spleen / Q000378:metabolism* / Q000503:physiopathology; D013449:Sulfonamides / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014680:Veins / Q000378:metabolism / Q000503:physiopathology
chemical_list: D000959:Antihypertensive Agents; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D013449:Sulfonamides; D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D010396:Penicillamine; D000077300:Bosentan; D019331:NG-Nitroarginine Methyl Ester