Differential Responses of Targeted Lung Redox Enzymes to Rat Exposure to 60 or 85% Oxygen

Authors

Zhuohui Gan, Marquette UniversityFollow
David L. Roerig, Medical College of Wisconsin
Anne V. Clough, Marquette UniversityFollow
Said H. Audi, Marquette UniversityFollow

Document Type

Article

Language

eng

Format of Original

13 p.

Publication Date

7-2011

Publisher

American Physiological Society

Source Publication

Journal of Applied Physiology

Source ISSN

0021-8987

Original Item ID

doi: 10.1152/japplphysiol.01451.2010

Abstract

Rat exposure to 60% O₂ (hyper-60) or 85% O₂ (hyper-85) for 7 days confers susceptibility or tolerance, respectively, of the otherwise lethal effects of exposure to 100% O₂. The objective of this study was to determine whether activities of the antioxidant cytosolic enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) and mitochondrial complex III are differentially altered in hyper-60 and hyper-85 lungs. Duroquinone (DQ), an NQO1 substrate, or its hydroquinone (DQH₂), a complex III substrate, was infused into the arterial inflow of isolated, perfused lungs, and the venous efflux rates of DQH₂ and DQ were measured. Based on inhibitor effects and kinetic modeling, capacities of NQO1-mediated DQ reduction (V_max1) and complex III-mediated DQH₂ oxidation (V_max2) increased by ∼140 and ∼180% in hyper-85 lungs, respectively, compared with rates in lungs of rats exposed to room air (normoxic). In hyper-60 lungs, V_max1 increased by ∼80%, with no effect on V_max2. Additional studies revealed that mitochondrial complex I activity in hyper-60 and hyper-85 lung tissue homogenates was ∼50% lower than in normoxic lung homogenates, whereas mitochondrial complex IV activity was ∼90% higher in only hyper-85 lung tissue homogenates. Thus NQO1 activity increased in both hyper-60 and hyper-85 lungs, whereas complex III activity increased in hyper-85 lungs only. This increase, along with the increase in complex IV activity, may counter the effects the depression in complex I activity might have on tissue mitochondrial function and/or reactive oxygen species production and may be important to the tolerance of 100% O₂ observed in hyper-85 rats.

Comments

Accepted version. Journal of Applied Physiology, Vol. 111, No. 1 (July 2011): 95-107. DOI. © 2011 the American Physiological Society. Used with permission.

Recommended Citation

Gan, Zhuohui; Roerig, David L.; Clough, Anne V.; and Audi, Said H., "Differential Responses of Targeted Lung Redox Enzymes to Rat Exposure to 60 or 85% Oxygen" (2011). Biomedical Engineering Faculty Research and Publications. 282.
https://epublications.marquette.edu/bioengin_fac/282