L-arginine chlorination products inhibit endothelial nitric oxide production.
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.
Zhang
C
C
Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Reiter
C
C
Eiserich
J P
JP
Boersma
B
B
Parks
D A
DA
Beckman
J S
JS
Barnes
S
S
Kirk
M
M
Baldus
S
S
Darley-Usmar
V M
VM
White
C R
CR
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
D009569:Nitric Oxide; D002713:Chlorine; D001120:Arginine