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Electron paramagnetic resonance (EPR) oximetry as a quantitative tool to measure cellular respiration in pathophysiological conditions

Presley, Tennille D
http://rave.ohiolink.edu/etdc/view?acc_num=osu1187014988

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Biophysics.
EPR oximetry is a technique based on the paramagnetic distinctiveness of molecular oxygen. It is a non-consuming technique that allows repeated measurements of low levels of oxygen. Using ~10 µl of sample, molecular oxygen from the oxygen-induced EPR line broadening of a suitable paramagnetic probe such as lithium phthalocyanine (LiPc) may be determined. In the first portion, a new quantitative methodology for cellular respiration using EPR oximetry is established; where three phases of respiration can be observed: pO2-independent respiration, pO2-dependent respiration and a static equilibrium. Additionally, it is also demonstrated how the diffusion limitations can depend on cell density and consumption rate. Following, we introduce the application of the developed EPR procedure to study NO-regulated respiration. We conclude that at a low pO2, the reduction of respiration by endogenous NO does not occur through direct reversible inhibition of cytochrome c oxidase (CcO) at complex IV, by competing with O2. Lastly, heat shock protein 90 (Hsp90) and endothelial nitric oxide synthase (eNOS) are evaluated, based on their influential role on cellular respiration in various pathophysiological conditions such as heat shock, hypoxia and hyperglycemia. A mild heat shock increases the Hsp90-eNOS complex. The association of Hsp90 and eNOS enhances the production of NO, leading to a reduction in respiration. Exposure to extreme hypoxia can also minimize cellular respiration. It was hypothesized that the p50 increases in the presence of NO; however, we have found that the p50 remains unchanged. Similarly, the Hsp90-eNOS interaction enhances during hyperglycemia (up to 4 h). At a longer exposure, the Hsp90-eNOS complex diminishes. During a moderate hyperglycemic treatment (~8 h), the maximum O2 consumption rate is attenuated; where the p50 was unaffected. At longer exposures, this behavior is not present. To enhance the presence of the Hsp90-eNOS complex, heat shock was applied prior to hyperglycemia. As a result, the overall maximum respiration rate and interaction of Hsp90 and eNOS were restored. In summary, EPR oximetry is demonstrated as a prominent technique to measure oxygen. As a whole, this dissertation provides insight into certain mechanisms of cellular respiration and provides potential pathways to improve various pathophysiological conditions.
Govindasamy Ilangovan (Advisor)
159 p.
Biophysics, Medical
EPR oximetry; Oxygen; Heat shock protein (Hsp90); endothelial nitric oxide synthase (eNOS); Nitric oxide; Cellular respiration

Recommended Citations

Citations

  • Presley, T. D. (2007). Electron paramagnetic resonance (EPR) oximetry as a quantitative tool to measure cellular respiration in pathophysiological conditions [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1187014988

    APA Style (7th edition)

  • Presley, Tennille. Electron paramagnetic resonance (EPR) oximetry as a quantitative tool to measure cellular respiration in pathophysiological conditions. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1187014988.

    MLA Style (8th edition)

  • Presley, Tennille. "Electron paramagnetic resonance (EPR) oximetry as a quantitative tool to measure cellular respiration in pathophysiological conditions." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1187014988

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.