| 17601793 |
Merker MP, Audi SH, Lindemer BJ, Krenz GS, Bongard RD: Role of mitochondrial electron transport complex I in coenzyme Q1 reduction by intact pulmonary arterial endothelial cells and the effect of hyperoxia. Am J Physiol Lung Cell Mol Physiol. 2007 Sep;293(3):L809-19. Epub 2007 Jun 29.
The objective was to determine the impact of intact normoxic and hyperoxia-exposed (95% O (2) for 48 h) bovine pulmonary arterial endothelial cells in culture on the redox status of the coenzyme Q (10) homolog coenzyme Q (1) (CoQ (1)). When CoQ (1) (50 microM) was incubated with the cells for 30 min, its concentration in the medium decreased over time, reaching a lower level for normoxic than hyperoxia-exposed cells. The decreases in CoQ (1) concentration were associated with generation of CoQ (1) hydroquinone (CoQ (1) H (2)), wherein 3.4 times more CoQ (1) H (2) was produced in the normoxic than hyperoxia-exposed cell medium (8.2 +/- 0.3 and 2.4 +/- 0.4 microM, means +/- SE, respectively) after 30 min. The maximum CoQ (1) reduction rate for the hyperoxia-exposed cells, measured using the cell membrane-impermeant redox indicator potassium ferricyanide, was about one-half that of normoxic cells (11.4 and 24.1 nmol x min (-1) x mg (-1) cell protein, respectively). The mitochondrial electron transport complex I inhibitor rotenone decreased the CoQ (1) reduction rate by 85% in the normoxic cells and 44% in the hyperoxia-exposed cells. There was little or no inhibitory effect of NAD (P) H:quinone oxidoreductase 1 (NQO1) inhibitors on CoQ (1) reduction. Intact cell oxygen consumption rates and complex I activities in mitochondria-enriched fractions were also lower for hyperoxia-exposed than normoxic cells. The implication is that intact pulmonary endothelial cells influence the redox status of CoQ (1) via complex I-mediated reduction to CoQ (1) H (2), which appears in the extracellular medium, and that the hyperoxic exposure decreases the overall CoQ (1) reduction capacity via a depression in complex I activity. |
36(0,1,1,6) |