As critical as O2 is for maintaining cellular, and ultimately organismal homeostasis, there is little specific information that quantifies the relationship between intracellular O2 levels and cell function. The objective of this project is to continue experimentation designed to determine the O2 dependence of cell respiration, metabolism, and function in isolated single skeletal muscle fibers. Specifically, we will test the general hypotheses single skeletal muscle fibers. Specifically, we will test the general hypotheses that cellular function is affected, both directly and indirectly, by intracellular [O2] levels considerably above those considered rate limiting. for isolated mitochondria. Single, membrane intact, skeletal muscle fibers will be isolated from Xenopus laevis and placed into a chamber in which the extracellular milieu can be precisely controlled, metabolic and respiratory rate can be varied by stimulation, Q2 uptake measured, and optical imaging can be conducted. To test our primary hypothesis, intracellular P02 will be measured (using a phosphorescence lifetime technique) under varied conditions and the relationships between cell P02 and respiratory, glycolytic rate, the regulators of oxidative phosphorylation, and the regulation of contractile function will be determined. The relationship between mitochondrial density (and distribution) and the processes listed above will be examined in three different Xenopus fiber types. In addition, experiments are proposed that test hypotheses concerning the importance of myoglobin in intracellular O2 transport, potential intracellular O2 sensors, causes of cell damage related to inadequate oxygenation, and energy sources for contractile work with altered oxygenation. By utilizing an isolated single skeletal muscle cell, intrinsic properties of the working cell can be investigated without confounding factors of microcirculation and fiber type heterogeneities. The originality and significance of the proposed experiments residue in the integration of several established and new techniques to investigate cell function as it is affected by [O2], and the unique research expertise of the personnel assembled in this program project application provides a singular opportunity to study these processes. The proposed studies will provide valuable information defining the O2 dependence of cellular function; which has direct implications concerning cell, organ, and organismal health, particularly during disease states involving O2 deprivation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL017731-28
Application #
6589833
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
2002-05-01
Project End
2003-04-30
Budget Start
Budget End
Support Year
28
Fiscal Year
2002
Total Cost
$246,248
Indirect Cost
Name
University of California San Diego
Department
Type
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Olfert, I Mark; Malek, Moh H; Eagan, Tomas M L et al. (2014) Inflammatory cytokine response to exercise in alpha-1-antitrypsin deficient COPD patients 'on' or 'off' augmentation therapy. BMC Pulm Med 14:106
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Koga, S; Wüst, R C I; Walsh, B et al. (2013) Increasing temperature speeds intracellular PO2 kinetics during contractions in single Xenopus skeletal muscle fibers. Am J Physiol Regul Integr Comp Physiol 304:R59-66
Breen, Ellen C; Malloy, Jaret L; Tang, Kechun et al. (2013) Impaired pulmonary defense against Pseudomonas aeruginosa in VEGF gene inactivated mouse lung. J Cell Physiol 228:371-9
Tang, Kechun; Murano, George; Wagner, Harrieth et al. (2013) Impaired exercise capacity and skeletal muscle function in a mouse model of pulmonary inflammation. J Appl Physiol 114:1340-50
Wray, D Walter; Nishiyama, Steven K; Donato, Anthony J et al. (2011) The paradox of oxidative stress and exercise with advancing age. Exerc Sport Sci Rev 39:68-76
Esposito, Fabio; Mathieu-Costello, Odile; Entin, Pauline L et al. (2010) The skeletal muscle VEGF mRNA response to acute exercise in patients with chronic heart failure. Growth Factors 28:139-47
Wray, D Walter; Nishiyama, Steve K; Donato, Anthony J et al. (2010) Human vascular aging: limb-specific lessons. Exerc Sport Sci Rev 38:177-85

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