Faculty Collaboration Database

Native LDL and minimally oxidized LDL differentially regulate superoxide anion in vascular endothelium in situ. Am J Physiol Heart Circ Physiol 2002 Aug;283(2):H750-9

Date

07/19/2002

Pubmed ID

12124224

DOI

10.1152/ajpheart.00029.2002

Scopus ID

2-s2.0-0036070498 (requires institutional sign-in at Scopus site)   69 Citations

Abstract

Low-density lipoprotein (LDL) and its oxidized derivatives are hypothesized to impair vascular function by increasing superoxide anion (O.). To investigate mechanisms in situ, isolated carotid arteries were incubated with native LDL (nLDL) or minimally oxidized LDL (mmLDL). With the use of en face fluorescent confocal microscopy and hydroethidine, an oxidant-sensitive fluorescent probe, we found that nLDL increased O. in vascular endothelium greater than fourfold by an N(omega)-nitro-L-arginine methyl ester (L-NAME)-inhibitable mechanism. In contrast, mmLDL increased O. in vascular endothelium greater than eightfold by mechanisms that were partially inhibited by L-NAME and allopurinol and essentially ablated by diphenyleneiodium. These data indicate that both nLDL and mmLDL uncouple endothelial nitric oxide synthase (eNOS) activity and that mmLDL also activates xanthine oxidase and NADPH oxidoreductase to induce greater increases in O. generation than nLDL. Western analysis revealed that both lipoproteins inhibited A-23187-stimulated association of heat shock protein 90 (HSP90) with eNOS without inhibiting phosphorylation of eNOS at serine-1179 (phospho-eNOS), an immunological index of electron flow through the enzyme. As HSP90 mediates the balance of.NO and O. generation by eNOS, these data provide new insight into the mechanisms by which oxidative stress, induced by nLDL and mmLDL, uncouple eNOS activity to increase endothelial O. generation.

Author List

Stepp DW, Ou J, Ackerman AW, Welak S, Klick D, Pritchard KA Jr

Authors

Kirkwood A. Pritchard PhD Professor in the Surgery department at Medical College of Wisconsin
Scott R. Welak MD Associate Professor in the Pediatrics department at Medical College of Wisconsin

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

Animals
Carotid Arteries
Dogs
Endothelium, Vascular
Enzyme Activation
HSP90 Heat-Shock Proteins
Humans
Lipoproteins, LDL
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
Organ Culture Techniques
Reactive Oxygen Species
Superoxides