Faculty Collaboration Database

Reticulocyte 15-lipoxygenase-I is important in acetylcholine-induced endothelium-dependent vasorelaxation in rabbit aorta. Arterioscler Thromb Vasc Biol 2006 Jan;26(1):78-84

Date

10/22/2005

Pubmed ID

16239596

DOI

10.1161/01.ATV.0000191640.73313.ad

Scopus ID

2-s2.0-33644824103 (requires institutional sign-in at Scopus site)   29 Citations

Abstract

OBJECTIVE: Aortic 15-lipoxygenase (15-LO) metabolizes arachidonic acid (AA) to 15-hydroperoxyeicosatetraenoic acid, which is then converted to the vasodilators 15-hydroxy-11,12-epoxyeicosatrienoic acid and 11,12,15-trihydroxyeicosatrienoic acid. These metabolites contribute to endothelium-dependent relaxations of rabbit aorta to AA and acetylcholine. We investigated the identity of rabbit aortic 15-LO and studied its importance in the regulation of vascular tone.

METHODS AND RESULTS: RT-PCR using 12-lipoxygenase/15-LO specific primers resulted in a 572-bp product with a sequence identical to 15-LO-I from rabbit aorta. A RT-PCR/restriction digest strategy excluded expression of 12-lipoxygenase. Immunoblotting revealed 15-LO-I expression in rabbit endothelial and smooth muscle cells. Aortic homogenates and cytosolic fractions metabolize AA to 15(S)-hydroxyeicosatetraenoic acid and linoleic acid to 13(S)-hydroxyoctadecadienoic acid. This activity was blocked by LO inhibitors. The kinetic characteristics (Michaelis constant of aortic 15-LO is 2.2+/-0.3 micromol/L for AA and 23.5+/-3.3 micromol/L for linoleic acid) of aortic 15-LO were similar to those of the purified 15-LO-I. An antisense oligonucleotide inhibited 15-LO-I expression in rabbit aorta. Indomethacin and nitro-L-arginine-resistant relaxations to acetylcholine were inhibited by 15-LO-I antisense oligonucleotide but not by the scrambled oligonucleotide.

CONCLUSIONS: 15-LO-I is expressed in rabbit aortic endothelium and is important in endothelium-dependent regulation of vascular tone.

Author List

Tang X, Holmes BB, Nithipatikom K, Hillard CJ, Kuhn H, Campbell WB

Authors

William B. Campbell PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin
Cecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acetylcholine
Amino Acid Sequence
Animals
Aorta
Arachidonate 12-Lipoxygenase
Arachidonate 15-Lipoxygenase
Cells, Cultured
Cytosol
Endothelium, Vascular
Gene Expression Regulation, Enzymologic
Humans
Isometric Contraction
Molecular Sequence Data
Muscle, Smooth, Vascular
Rabbits
Reticulocytes
Vasodilation
Vasodilator Agents