title: L-arginine chlorination products inhibit endothelial nitric oxide production.
abstract: The myeloperoxidase-derived oxidant hypochlorous acid (HOCl) is thought to contribute to endothelial dysfunction, but the mechanisms underlying this inhibitory effect are unknown. The present study tested the hypothesis that HOCl and L-arginine (L-Arg) react to form novel compounds that adversely affect endothelial function by inhibiting nitric oxide (NO) formation. Using spectrophotometric techniques, we found that HOCl and L-Arg react rapidly (k = 7.1 x 10(5) m(-1) s(-1)) to form two major products that were identified by mass spectrometry as monochlorinated and dichlorinated adducts of L-Arg. Pretreatment of bovine aortic endothelial cells with the chlorinated L-Arg metabolites (Cl-l-Arg) inhibited the -induced formation of the NO metabolites nitrate (NO(3)(-)) and nitrite (NO(2)(-)) in a concentration-dependent manner. Preincubation of rat aortic ring segments with Cl-L-Arg resulted in concentration-dependent inhibition of acetylcholine-induced relaxation. In contrast, blood vessels relaxed normally to the endothelium-independent vasodilator sodium nitroprusside. In vivo administration of Cl-L-Arg to anesthetized rats increased carotid artery vascular resistance. A greater than 10-fold excess of L-Arg was required to reverse the inhibitory effects of Cl-L-Arg in vivo and in vitro. Reaction of HOCl with D-arginine (D-Arg) did not result in the formation of inhibitory products. These results suggest that HOCl reacts with L-Arg to form chlorinated products that act as nitric-oxide synthase inhibitors.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: C
authors.initials: C
authors.lastname: Reiter
authors.forename: J P
authors.initials: JP
authors.lastname: Eiserich
authors.forename: B
authors.initials: B
authors.lastname: Boersma
authors.forename: D A
authors.initials: DA
authors.lastname: Parks
authors.forename: J S
authors.initials: JS
authors.lastname: Beckman
authors.forename: S
authors.initials: S
authors.lastname: Barnes
authors.forename: M
authors.initials: M
authors.lastname: Kirk
authors.forename: S
authors.initials: S
authors.lastname: Baldus
authors.forename: V M
authors.initials: VM
authors.lastname: Darley-Usmar
authors.forename: C R
authors.initials: CR
authors.lastname: White
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism*; D002417:Cattle; D002713:Chlorine / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D009569:Nitric Oxide; D002713:Chlorine; D001120:Arginine