title: Endothelial 15-lipoxygenase-1 overexpression increases acetylcholine-induced hypotension and vasorelaxation in rabbits.
abstract: Arachidonic acid is metabolized by the 15-lipoxygenase-1 pathway to the vasodilatory eicosanoids hydroxy-epoxyeicosatrienoic acid and trihydroxyeicosatrienoic acid. We determined the in vitro and in vivo effects of the 15-lipoxygenase-1 metabolites in rabbits infected with adenovirus containing cDNA for human 15-lipoxygenase-1 (Ad-15-LO-1). Forty hours after intravenous adenoviral injection, 15-lipoxygenase-1 expression increased in liver and mesenteric arteries 10-fold and 3-fold, respectively. Expression of 15-LO-1 was limited to the endothelium of mesenteric arteries. Overexpression did not occur in tissues from rabbits infected with a beta-galactosidase containing adenovirus. Trihydroxyeicosatrienoic acid and hydroxy-epoxyeicosatrienoic acid synthesis per milligram of tissue increased by 2.1- and 1.5-fold, respectively, in mesenteric arteries from Ad-15-LO-1-infected rabbits compared with normal rabbits. Pretreatment with a 15-lipoxygenase inhibitor BW755C inhibited the synthesis. NO and prostaglandin-independent, maximal relaxations to acetylcholine were greater in mesenteric arteries from Ad-15-LO-1-infected rabbits (98.3+/-1.7%) compared with normal (60.93+/-10.5%) and beta-galactosidase containing adenovirus-infected rabbits (68.3+/-7.7%). Pretreatment with BW755C decreased these relaxations. Mean arterial pressure and heart rate did not differ in Ad-15-LO-1-infected rabbits compared with normal or beta-galactosidase containing adenovirus-infected rabbits. The hypotensive responses to acetylcholine in the presence and absence of inhibition of NO and prostaglandins were greater in Ad-15-LO-1-infected rabbits (-52+/-2% and -47+/-2%) compared with normal (-31+/-3% and -25+/-5%) or beta-galactosidase containing adenovirus-infected rabbits (-38+/-2% and -30+/-3%). Therefore, increased expression of 15-LO-1 increases acetylcholine relaxation in arteries and hypotensive responses in rabbits because of increased hydroxy-epoxyeicosatrienoic acid and trihydroxyeicosatrienoic acid synthesis.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA.
authors.forename: Nitin T
authors.initials: NT
authors.lastname: Aggarwal
authors.forename: Yuttanna
authors.initials: Y
authors.lastname: Chawengsub
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Gauthier
authors.forename: Helena
authors.initials: H
authors.lastname: Viita
authors.forename: Seppo
authors.initials: S
authors.lastname: Yla-Herttuala
authors.forename: William B
authors.initials: WB
authors.lastname: Campbell
mesh_terms: D000109:Acetylcholine; D000818:Animals; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D001158:Arteries / Q000201:enzymology / Q000503:physiopathology*; D015153:Blotting, Western; D004730:Endothelium, Vascular / Q000201:enzymology*; D018014:Gene Transfer Techniques; D006439:Hemodynamics; D006801:Humans; D007022:Hypotension / Q000139:chemically induced* / Q000503:physiopathology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007537:Isometric Contraction; D008099:Liver / Q000098:blood supply; D008638:Mesenteric Arteries / Q000503:physiopathology; D011817:Rabbits; D015854:Up-Regulation; D014664:Vasodilation; D014665:Vasodilator Agents
chemical_list: D007527:Isoenzymes; D014665:Vasodilator Agents; D016718:Arachidonic Acid; D001093:Arachidonate 15-Lipoxygenase; D000109:Acetylcholine