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Impact of pulmonary arterial endothelial cells on duroquinone redox status. Free Radic Biol Med 2004 Jul 01;37(1):86-103

Date

06/09/2004

Pubmed ID

15183197

DOI

10.1016/j.freeradbiomed.2004.02.078

Scopus ID

2-s2.0-2942562276 (requires institutional sign-in at Scopus site)   15 Citations

Abstract

The study objective was to use pulmonary arterial endothelial cells to examine kinetics and mechanisms contributing to the disposition of the quinone 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ) observed during passage through the pulmonary circulation. The approach was to add DQ, durohydroquinone (DQH2), or DQ with the cell membrane-impermeant oxidizing agent, ferricyanide (Fe(CN)6(3)-), to the cell medium, and to measure the medium concentrations of substrates and products over time. Studies were carried out under control conditions and with dicumarol, to inhibit NAD(P)H:quinone oxidoreductase 1 (NQO1), or cyanide, to inhibit mitochondrial electron transport. In control cells, DQH2 appears in the extracellular medium of cells incubated with DQ, and DQ appears when the cells are incubated with DQH2. Dicumarol blocked the appearance of DQH2 when DQ was added to the cell medium, and cyanide blocked the appearance of DQ when DQH2 was added to the cell medium, suggesting that the two electron reductase NQO1 dominates DQ reduction and mitochondrial electron transport complex III is the predominant route of DQH2 oxidation. In the presence of cyanide, the addition of DQ also resulted in an increased rate of appearance of DQH2 and stimulation of cyanide-insensitive oxygen consumption. As DQH2 does not autoxidize-comproportionate over the study time course, these observations suggest a cyanide-stimulated one-electron DQ reduction and durosemiquinone (DQ*-) autoxidation. The latter processes are apparently confined to the cell interior, as the cell membrane impermeant oxidant, ferricyanide, did not inhibit the DQ-stimulated cyanide-insensitive oxygen consumption. Thus, regardless of whether DQ is reduced via a one- or two-electron reduction pathway, the net effect in the extracellular medium is the appearance of DQH2. These endothelial redox functions and their apposition to the vessel lumen are consistent with the pulmonary endothelium being an important site of DQ reduction to DQH2 observed in the lungs.

Author List

Merker MP, Bongard RD, Krenz GS, Zhao H, Fernandes VS, Kalyanaraman B, Hogg N, Audi SH

Authors

Said Audi PhD Professor in the Biomedical Engineering department at Marquette University
Neil Hogg PhD Associate Dean, Professor in the Biophysics department at Medical College of Wisconsin
Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of Wisconsin




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

Animals
Benzoquinones
Cattle
Cells, Cultured
Endothelium, Vascular
Kinetics
Linoleic Acid
Models, Biological
Oxidation-Reduction
Pulmonary Artery