title: Role of arachidonic acid lipoxygenase metabolites in acetylcholine-induced relaxations of mouse arteries.
abstract: Arachidonic acid (AA) metabolites function as EDHFs in arteries of many species. They mediate cyclooxygenase (COX)- and nitric oxide (NO)-independent relaxations to acetylcholine (ACh). However, the role of AA metabolites as relaxing factors in mouse arteries remains incompletely defined. ACh caused concentration-dependent relaxations of the mouse thoracic and abdominal aorta and carotid, femoral, and mesentery arteries (maximal relaxation: 57 ± 4%, 72 ± 4%, 82 ± 3%, 80 ± 3%, and 85 ± 3%, respectively). The NO synthase inhibitor nitro-L-arginine (L-NA; 30 μM) blocked relaxations in the thoracic aorta, and L-NA plus the COX inhibitor indomethacin (10 μM) inhibited relaxations in the abdominal aorta and carotid, femoral, and mesenteric arteries (maximal relaxation: 31 ± 10%, 33 ± 5%, 41 ± 8%, and 73 ± 3%, respectively). In mesenteric arteries, NO- and COX-independent relaxations to ACh were inhibited by the lipoxygenase (LO) inhibitors nordihydroguaiaretic acid (NDGA; 10 μM) and BW-755C (200 μM), the K(+) channel inhibitor apamin (1 μM), and 60 mM KCl and eliminated by endothelium removal. They were not altered by the cytochrome P-450 inhibitor N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (20 μM) or the epoxyeicosatrienoic acid antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (10 μM). AA relaxations were attenuated by NDGA or apamin and eliminated by 60 mM KCl. Reverse-phase HPLC analysis revealed arterial [(14)C]AA metabolites that comigrated with prostaglandins, trihydroxyeicosatrienoic acids (THETAs), hydroxyepoxyeicosatrienoic acids (HEETAs), and hydroxyeicosatetraenoic acids (HETEs). Epoxyeicosatrienoic acids were not observed. Mass spectrometry confirmed the identity of 6-keto-PGF(1α), PGE(2), 12-HETE, 15-HETE, HEETAs, 11,12,15-THETA, and 11,14,15-THETA. AA metabolism was blocked by NDGA and endothelium removal. 11(R),12(S),15(S)-THETA relaxations (maximal relaxation: 73 ± 3%) were endothelium independent and blocked by 60 mM KCl. Western immunoblot analysis and RT-PCR of the aorta and mesenteric arteries demonstrated protein and mRNA expression of leukocyte-type 12/15-LO. Thus, in mouse resistance arteries, 12/15-LO AA metabolites mediate endothelium-dependent relaxations to ACh and AA.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. kgauth@mcw.edu
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Gauthier
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Goldman
authors.forename: Nitin T
authors.initials: NT
authors.lastname: Aggarwal
authors.forename: Yuttana
authors.initials: Y
authors.lastname: Chawengsub
authors.forename: J R
authors.initials: JR
authors.lastname: Falck
authors.forename: William B
authors.initials: WB
authors.lastname: Campbell
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism*; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D001091:Arachidonate Lipoxygenases / Q000378:metabolism*; D001158:Arteries / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D019335:Nitroarginine / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000378:metabolism*
chemical_list: D000577:Amides; C121756:N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide; D014665:Vasodilator Agents; D019335:Nitroarginine; D001030:Apamin; D009637:Masoprocol; C067407:14,15-episulfide eicosatrienoic acid; D001091:Arachidonate Lipoxygenases; D015126:8,11,14-Eicosatrienoic Acid; D000109:Acetylcholine; D007213:Indomethacin