Impact of pulmonary arterial endothelial cells on duroquinone redox status

Authors

Marilyn P. Merker, Medical College of Wisconsin
Robert D. Bongard, Medical College of Wisconsin
Gary S. Krenz, Marquette UniversityFollow
Hongtao Zhao, Medical College of Wisconsin
Viola S. Fernandes, Marquette University
Balaraman Kalyanaraman, Medical College of Wisconsin
Neil Hogg, Medical College of Wisconsin
Said H. Audi, Marquette UniversityFollow

Document Type

Article

Language

eng

Format of Original

8 p.

Publication Date

7-2004

Publisher

Elsevier

Source Publication

Free Radical Biology and Medicine

Source ISSN

0891-5849

Original Item ID

doi: 10.1016/j.freeradbiomed.2004.02.078

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)₆³⁻), 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.

Comments

Free Radical Biology and Medicine, Volume 37, Issue 1, pp 86-103 (July, 2004). DOI:

Recommended Citation

Merker, Marilyn P.; Bongard, Robert D.; Krenz, Gary S.; Zhao, Hongtao; Fernandes, Viola S.; Kalyanaraman, Balaraman; Hogg, Neil; and Audi, Said H., "Impact of pulmonary arterial endothelial cells on duroquinone redox status" (2004). Biomedical Engineering Faculty Research and Publications. 5.
https://epublications.marquette.edu/bioengin_fac/5