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Artículos de revistas sobre el tema "Oxygen (O2)"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 6 de febrero de 2022

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1

Reading, Stacey A., and Maggie Yeomans. "Oxygen absorption by skin exposed to oxygen supersaturated water." Canadian Journal of Physiology and Pharmacology 90, no. 5 (May 2012): 515–24. http://dx.doi.org/10.1139/y2012-020.

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The present study tests the hypothesis that skin on the plantar surface of the foot absorbs oxygen (O2) when immersed in water that has a high dissolved O2 content. Healthy male and female subjects (24.2 ± 1.4 years) soaked each foot in tap water (1.7 ± 0.1 mg O2·L–1; 30.7 ± 0.3 °C) or O2-infused water (50.2 ± 1.7 mg O2·L–1; 32.1 ± 0.5 °C) for up to 30 min in 50 different experiments. Transcutaneous oximetry and near infrared spectroscopy were used to evaluate changes in skin PO2, oxygenated haemoglobin, and cytochrome oxidase aa3 that resulted from treatment. Compared with the tap water condi

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2

Mangum, C. P. "Oxygen transport in invertebrates." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, no. 5 (May 1, 1985): R505—R514. http://dx.doi.org/10.1152/ajpregu.1985.248.5.r505.

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The distribution of the O2 carrying proteins suggests that the original transport system was a hemoglobin similar to the alpha-chain of hemoglobin A and packaged in a nucleated red blood cell. These molecules, which occur in large open fluid compartments, function as O2 stores for regular periods of hypoxia as well as carriers between sites of gas exchange. When the closed circulatory system first arose, the red blood cell was abandoned in favor of extracellular heme proteins, and the O2 storage function became less important. Alternative O2 carriers, hemerythrins, appear in the blood at about

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3

Hochachka, P. W. "Metabolic suppression and oxygen availability." Canadian Journal of Zoology 66, no. 1 (January 1, 1988): 152–58. http://dx.doi.org/10.1139/z88-021.

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The aerobic metabolic rates of cells, tissues, and even whole organisms remain relatively constant down to very low values (O2-regulating response) or decline steadily with O2 availability (O2-conforming response). (O2-regulating systems attempt to make up the energy deficit arising when O2 uptake begins to decline by activating anaerobic metabolism; this process is termed the Pasteur effect and typically involves 5- to 15-fold increases in glucose utilization rates. O2 conformers do not make up the energy deficit and thus enter a metabolically arrested state as O2 availability declines. Curre

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4

Hoffman, David L., and Paul S. Brookes. "Oxygen Sensitivity of Mitochondrial Reactive Oxygen Species Generation Depends on Metabolic Conditions." Journal of Biological Chemistry 284, no. 24 (April 14, 2009): 16236–45. http://dx.doi.org/10.1074/jbc.m809512200.

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The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O2] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O2]. In the current study, we used a wide variety of substrates and inhibitors to probe the O2 sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent Km for O2 of putative ROS-generating sites wi

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5

Kizaki, Z., and R. G. Thurman. "Stimulation of oxygen uptake by glucagon is oxygen dependent in perfused rat liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 256, no. 2 (February 1, 1989): G369—G376. http://dx.doi.org/10.1152/ajpgi.1989.256.2.g369.

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Livers from well-fed female Sprague-Dawley rats (100-150 g) were perfused at flow rates of 4 or 8 ml.g liver-1.min-1 to deliver O2 to the organ at various rates. During perfusion at normal flow rates (4 ml.g-1.min-1), glucagon (10 nM) increased O2 uptake in perfused liver by approximately 40 mumol.g-1.h-1. In contrast, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 when livers were perfused at high flow rates. Increase in O2 uptake was directly proportional to flow rate and was blocked partially by infusion of phorbol myristate acetate (100 nM) before glucagon. Increase in O2 uptake

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6

Nakagawa, Y., T. Matsumura, M. Goto, W. Qu, F. C. Kauffman, and R. G. Thurman. "Increase in oxygen uptake due to arachidonic acid is oxygen dependent in the perfused liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 266, no. 5 (May 1, 1994): G953—G959. http://dx.doi.org/10.1152/ajpgi.1994.266.5.g953.

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The purpose of this study was to determine whether the effect of arachidonic acid on hepatic O2 uptake is O2 dependent and which region of the liver lobule it affects. In livers perfused at normal flow rates, infusion of arachidonate increased O2 uptake significantly by about 20-25 mumol.g-1.h-1. When the flow rate was doubled to make the hepatic O2 gradient shallower, the increase in O2 uptake due to arachidonate was two to three times larger (i.e., approximately 50 mumol.g-1.h-1). In livers perfused in the retrograde direction, maximal rates of O2 uptake were about twofold higher in upstream

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7

Puntarulo, S., and A. I. Cederbaum. "Effect of oxygen concentration on microsomal oxidation of ethanol and generation of oxygen radicals." Biochemical Journal 251, no. 3 (May 1, 1988): 787–94. http://dx.doi.org/10.1042/bj2510787.

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The iron-catalysed production of hydroxyl radicals, by rat liver microsomes (microsomal fractions), assessed by the oxidation of substrate scavengers and ethanol, displayed a biphasic response to the concentration of O2 (varied from 3 to 70%), reaching a maximal value with 20% O2. The decreased rates of hydroxyl-radical generation at lower O2 concentrations correlates with lower rates of production of H2O2, the precursor of hydroxyl radical, whereas the decreased rates at elevated O2 concentrations correlate with lower rates (relative to 20% O2) of activity of NADPH-cytochrome P-450 reductase,

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8

Han, Jiuli, Lu Bai, Bingbing Yang, Yinge Bai, Shuangjiang Luo, Shaojuan Zeng, Hongshuai Gao, et al. "Highly Selective Oxygen/Nitrogen Separation Membrane Engineered Using a Porphyrin-Based Oxygen Carrier." Membranes 9, no. 9 (September 3, 2019): 115. http://dx.doi.org/10.3390/membranes9090115.

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Air separation is very important from the viewpoint of the economic and environmental advantages. In this work, defect-free facilitated transport membranes based on poly(amide-12-b-ethylene oxide) (Pebax-2533) and tetra(p-methoxylphenyl)porphyrin cobalt chloride (T(p-OCH3)PPCoCl) were fabricated in systematically varied compositions for O2/N2 separation. T(p-OCH3)PPCoCl was introduced as carriers that selectively and reversibly interacted with O2 and facilitated O2 transport in the membrane. The T(p-OCH3)PPCoCl had good compatibility with the Pebax-2533 via the hydrogen bond interaction and fo

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9

Zhou, J., B. Delille, F. Brabant, and J. L. Tison. "Insights into oxygen transport and net community production in sea ice from oxygen, nitrogen and argon concentrations." Biogeosciences 11, no. 18 (September 18, 2014): 5007–20. http://dx.doi.org/10.5194/bg-11-5007-2014.

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Abstract. We present and compare the dynamics (i.e., changes in standing stocks, saturation levels and concentrations) of O2, Ar and N2 in landfast sea ice, collected in Barrow (Alaska), from February through June 2009. The comparison suggests that the dynamic of O2 in sea ice strongly depends on physical processes (gas incorporation and subsequent transport). Since Ar and N2 are only sensitive to the physical processes in the present study, we then discuss the use of O2 / Ar and O2 / N2 to correct for the physical contribution to O2 supersaturations, and to determine the net community product

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10

Trushina, Aleksandra P., Veniamin G. Goldort, Sergei A. Kochubei та Alexey V. Baklanov. "UV-photoexcitation of encounter complexes of oxygen O2–O2 as a source of singlet oxygen O2(1Δg) in gas phase". Chemical Physics Letters 485, № 1-3 (січень 2010): 11–15. http://dx.doi.org/10.1016/j.cplett.2009.11.058.

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11

Zhou, J., B. Delille, F. Brabant, and J. L. Tison. "Insights into oxygen transport and net community production in sea ice from oxygen, nitrogen and argon concentrations." Biogeosciences Discussions 11, no. 2 (February 4, 2014): 2045–81. http://dx.doi.org/10.5194/bgd-11-2045-2014.

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Abstract. We present the evolution of O2 standing stocks, saturation levels and concentrations in landfast sea ice, collected in Barrow (Alaska), from February to June 2009. The comparison of the standing stocks and saturation levels of O2 against those of N2 and Ar suggests that the dynamic of O2 in sea ice strongly depends on physical processes (gas incorporation and subsequent transport). We then discuss on the use of O2 / Ar and O2 / N2 to correct for the physical contribution and to determine the biological contribution (NCP) to O2 supersaturations. We conclude that O2 / Ar suits better t

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12

Trimbee, Annette M., and E. E. Prepas. "Dependence of Lake Oxygen Depletion Rates on Maximum Oxygen Storage in a Partially Meromictic Lake in Alberta." Canadian Journal of Fisheries and Aquatic Sciences 45, no. 3 (March 1, 1988): 571–76. http://dx.doi.org/10.1139/f88-069.

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Areal rates of hypolimnetic oxygen depletion (AHOD) and winter oxygen depletion (AWOD) varied considerably from year to year in a partially meromictic lake (Narrow Lake) in central Alberta. AHOD ranged from 0.222 to 0.522 g O2∙m−2∙d−1 over four summers and AWOD ranged from 0.354 to 0.614 g O2∙m−2∙d−1 over three winters. AHOD was positively correlated with maximum storage of dissolved oxygen (O2) at the onset of summer thermal stratification (P < 0.05). Similarly, AWOD was higher in years when mixing was more complete and maximum O2 storage at freeze-up was higher. These results suggest that

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13

Murphy, Michael P. "How mitochondria produce reactive oxygen species." Biochemical Journal 417, no. 1 (December 12, 2008): 1–13. http://dx.doi.org/10.1042/bj20081386.

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The production of ROS (reactive oxygen species) by mammalian mitochondria is important because it underlies oxidative damage in many pathologies and contributes to retrograde redox signalling from the organelle to the cytosol and nucleus. Superoxide (O2•−) is the proximal mitochondrial ROS, and in the present review I outline the principles that govern O2•− production within the matrix of mammalian mitochondria. The flux of O2•− is related to the concentration of potential electron donors, the local concentration of O2 and the second-order rate constants for the reactions between them. Two mod

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14

Samsel, R. W., D. Cherqui, A. Pietrabissa, W. M. Sanders, M. Roncella, J. C. Emond, and P. T. Schumacker. "Hepatic oxygen and lactate extraction during stagnant hypoxia." Journal of Applied Physiology 70, no. 1 (January 1, 1991): 186–93. http://dx.doi.org/10.1152/jappl.1991.70.1.186.

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As O2 delivery falls, tissues must extract increasing amounts of O2 from blood to maintain a normal O2 consumption. Below a critical delivery threshold, increases in O2 extraction cannot compensate for the falling delivery, and O2 uptake falls in a supply-dependent fashion. Numerous studies have identified a critical delivery in whole animals, but the regional contributions to the critical O2 delivery are less fully understood. In the present study, we explored the limits of O2 extraction in the isolated liver, seeking to determine 1) the normal relationship between O2 consumption and delivery

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15

Dean, Jay B., Daniel K. Mulkey, Richard A. Henderson, Stephanie J. Potter, and Robert W. Putnam. "Hyperoxia, reactive oxygen species, and hyperventilation: oxygen sensitivity of brain stem neurons." Journal of Applied Physiology 96, no. 2 (February 2004): 784–91. http://dx.doi.org/10.1152/japplphysiol.00892.2003.

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Hyperoxia is a popular model of oxidative stress. However, hyperoxic gas mixtures are routinely used for chemical denervation of peripheral O2 receptors in in vivo studies of respiratory control. The underlying assumption whenever using hyperoxia is that there are no direct effects of molecular O2 and reactive O2 species (ROS) on brain stem function. In addition, control superfusates used routinely for in vitro studies of neurons in brain slices are, in fact, hyperoxic. Again, the assumption is that there are no direct effects of O2 and ROS on neuronal activity. Research contradicts this assum

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16

Tsan, M. F., C. Y. Lee, and J. E. White. "Interleukin 1 protects rats against oxygen toxicity." Journal of Applied Physiology 71, no. 2 (August 1, 1991): 688–97. http://dx.doi.org/10.1152/jappl.1991.71.2.688.

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We studied the effect of interleukin 1 alpha (IL-1) in the protection against O2 toxicity. Tracheal insufflation of IL-1 resulted in a dose-dependent protection against O2 toxicity. All control rats died within 3 days of O2 exposure. In contrast, 84, 71, and 20% of rats insufflated with 5, 1, and 0.2 microgram(s) IL-1 (150, 30, and 6 x 10(4) U), respectively, survived 100% O2 exposure for greater than 11 days. At 2.3 days after O2 exposure, control rats showed severe pulmonary injury, which insufflation of 5 microgram(s) IL-1 markedly attenuated. The protection against O2 toxicity was associat

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17

Rocha, N. A. S., B. C. S. Leão, M. F. Accorsi, and G. Z. Mingoti. "90 INTRACELLULAR REACTIVE OXYGEN SPECIES IN BOVINE EMBRYOS CULTURED IN VITRO WITH CATALASE UNDER VARIOUS OXYGEN TENSIONS." Reproduction, Fertility and Development 24, no. 1 (2012): 157. http://dx.doi.org/10.1071/rdv24n1ab90.

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The production of reactive oxygen species (ROS), such as superoxide anion (O2–), hydroxyl radical (OH–) hydrogen peroxide (H2O2) and organic peroxides, is a normal process that occurs in the cellular mitochondrial respiratory chain. The high oxygen tension in in vitro culture (IVC) conditions is believed to induce oxidative stress, as a result of increase in ROS intracellular production, that can be correlated with embryonic developmental failure. Supplementation with antioxidants during IVC appears to increase the resistance of bovine embryos to the oxidative stress and consequently improve e

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18

Gonzalez-Fernandez, J. M., and S. E. Atta. "Comparative facilitated transport of oxygen." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, no. 1 (July 1, 1986): R1—R12. http://dx.doi.org/10.1152/ajpregu.1986.251.1.r1.

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Numerical solutions were obtained for a model of facilitated transport of O2. The dependence of the facilitated flow on the concentrations of O2 at the two boundaries of the transport path was studied. The numerical values of the parameters correspond to the adult Ascaris lumbricoides and to vertebrate red striated muscle. A global control principle is formulated. This states that for every fixed O2 concentration at the low concentration boundary there exists an O2 concentration at the high concentration boundary for which the facilitated flow is maximum. The collection of these maxima makes p

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19

Lewis, Daniel M., Kyung Min Park, Vitor Tang, Yu Xu, Koreana Pak, T. S. Karin Eisinger-Mathason, M. Celeste Simon, and Sharon Gerecht. "Intratumoral oxygen gradients mediate sarcoma cell invasion." Proceedings of the National Academy of Sciences 113, no. 33 (August 2, 2016): 9292–97. http://dx.doi.org/10.1073/pnas.1605317113.

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Hypoxia is a critical factor in the progression and metastasis of many cancers, including soft tissue sarcomas. Frequently, oxygen (O2) gradients develop in tumors as they grow beyond their vascular supply, leading to heterogeneous areas of O2 depletion. Here, we report the impact of hypoxic O2 gradients on sarcoma cell invasion and migration. O2 gradient measurements showed that large sarcoma mouse tumors (>300 mm3) contain a severely hypoxic core [≤0.1% partial pressure of O2 (pO2)] whereas smaller tumors possessed hypoxic gradients throughout the tumor mass (0.1–6% pO2). To analyze tumor

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20

Chen, Yifan, Pritmohinder S. Gill, and William J. Welch. "Oxygen availability limits renal NADPH-dependent superoxide production." American Journal of Physiology-Renal Physiology 289, no. 4 (October 2005): F749—F753. http://dx.doi.org/10.1152/ajprenal.00115.2005.

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Renal oxygen tension is substantially lower in the medulla than in the cortex and is reduced in hypertensive rats, a model of oxidative stress. Expression of NADPH oxidase, the primary source for superoxide anion (O2−·) in the kidney, is elevated in hypertension. Because molecular oxygen (O2) is required for O2−· formation, we tested the hypothesis that renal NADPH oxidase activity is limited by low O2. O2−· production by rat kidney tissue or cultured cells exposed to levels of Po2 that mimics those in the kidney was assessed by lucigenin-enhanced chemiluminescence. NADPH-dependent O2−· produc

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21

Gray, Mark E., Jamie R. K. Marland, Camelia Dunare, Ewen O. Blair, James Meehan, Andreas Tsiamis, Ian H. Kunkler, et al. "In vivo validation of a miniaturized electrochemical oxygen sensor for measuring intestinal oxygen tension." American Journal of Physiology-Gastrointestinal and Liver Physiology 317, no. 2 (August 1, 2019): G242—G252. http://dx.doi.org/10.1152/ajpgi.00050.2019.

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Recent advances in the fields of electronics and microfabrication techniques have led to the development of implantable medical devices for use within the field of precision medicine. Monitoring visceral surface tissue O2 tension ([Formula: see text]) by means of an implantable sensor is potentially useful in many clinical situations, including the perioperative management of patients undergoing intestinal resection and anastomosis. This concept could provide a means by which treatment could be tailored to individual patients. This study describes the in vivo validation of a novel, miniaturize

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22

Osaka, Masahiko, Ken Kurosaki, and Shinsuke Yamanaka. "Oxygen potential of (Pu0.91Am0.09)O2−x." Journal of Nuclear Materials 357, no. 1-3 (October 2006): 69–76. http://dx.doi.org/10.1016/j.jnucmat.2006.05.044.

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23

Otobe, Haruyoshi, Mitsuo Akabori, Yasuo Arai, and Kazuo Minato. "Oxygen Potentials of (Am0.5Np0.5)O2−x." Journal of the American Ceramic Society 92, no. 1 (January 2009): 174–78. http://dx.doi.org/10.1111/j.1551-2916.2008.02828.x.

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24

Schumacker, P. T., N. Chandel, and A. G. Agusti. "Oxygen conformance of cellular respiration in hepatocytes." American Journal of Physiology-Lung Cellular and Molecular Physiology 265, no. 4 (October 1, 1993): L395—L402. http://dx.doi.org/10.1152/ajplung.1993.265.4.l395.

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Cellular respiratory rates are normally determined by metabolic activity, but become rate limited by O2 availability if the cell O2 tension (PO2) falls below a critical value (typically 1–10 Torr). An ability to reduce metabolic activity and energy demand in response to a falling O2 availability might confer an increased resistance to a diminished O2 supply. Isolated rat hepatocytes were studied in primary culture under controlled O2 tensions. Cells were obtained by collagenase digestion and seeded into nutritive media in control and experimental spinner flasks at identical cell densities. Cel

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25

López-Barneo, José, Raquel del Toro, Konstantin L. Levitsky, María D. Chiara, and Patricia Ortega-Sáenz. "Regulation of oxygen sensing by ion channels." Journal of Applied Physiology 96, no. 3 (March 2004): 1187–95. http://dx.doi.org/10.1152/japplphysiol.00929.2003.

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O2 sensing is of critical importance for cell survival and adaptation of living organisms to changing environments or physiological conditions. O2-sensitive ion channels are major effectors of the cellular responses to hypoxia. These channels are preferentially found in excitable neurosecretory cells (glomus cells of the carotid body, cells in the neuroepithelial bodies of the lung, and neonatal adrenal chromaffin cells), which mediate fast cardiorespiratory adjustments to hypoxia. O2-sensitive channels are also expressed in the pulmonary and systemic arterial smooth muscle cells where they pa

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26

Sircar, S. S. "The oxygen-carrying flask: a representational transform of the oxygen dissociation curve of hemoglobin." Advances in Physiology Education 266, no. 6 (June 1994): S33. http://dx.doi.org/10.1152/advances.1994.266.6.s33.

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The teaching of oxygen transport by hemoglobin is supported by a graphic depiction of the sigmoid O2 dissociation curve of hemoglobin. However, a reconstruction of the same curve into an alternate paradigm, the "O2-carrying flask," affords a visual demonstration of the significance of its sigmoid shape and the implications of its shifts, which should be useful in elucidating certain aspects of O2 transport to undergraduate students of physiology. This article provides a mathematical justification for the flask design.

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27

Whipp, B. J., H. B. Rossiter, and S. A. Ward. "Exertional oxygen uptake kinetics: a stamen of stamina?" Biochemical Society Transactions 30, no. 2 (April 1, 2002): 237–47. http://dx.doi.org/10.1042/bst0300237.

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The fundamental pulmonary O2 uptake (o2) response to moderate, constant-load exercise can be characterized as (do2/dt)(τ) + Δo2 (t) = Δo2SS where Δo2SS is the steady-state response, and τ is the time constant, with the o2 kinetics reflecting intramuscular O2 uptake (o2) kinetics, to within 10%. The role of phosphocreatine (FCr) turnover in o2 control can be explored using 31P-MR spectroscopy, simultaneously with o2. Although τo2 and τPCr vary widely among subjects (approx. 20–65 s), they are not significantly different from each other, either at the on- or off-transient. A caveat to interpreti

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28

Poole, DC. "Current concepts of oxygen transport during exercise." Equine and Comparative Exercise Physiology 1, no. 1 (February 2004): 5–22. http://dx.doi.org/10.1079/ecp20036.

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AbstractThis brief review examines the athletic potential of mammals in general and the horse in particular as it relates to oxygen (O2) transport and utilization. The horse has been bred selectively for over six millennia based upon its ability to run fast. Whereas this has optimized cardiovascular and muscle function and the capacity to deliver and utilize O2, it has resulted in lung failure during intense exercise. Horses in their athletic prime are considered and attention is focused on their maximal capacities as related to O2 transport, irrespective of age per se. Following a few comment

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29

Midden, W. Robert, та Thomas A. Dahl. "Biological inactivation by single oxygen: distinguishing O2(1Δg) and O2(1Σg+)". Biochimica et Biophysica Acta (BBA) - General Subjects 1117, № 2 (вересень 1992): 216–22. http://dx.doi.org/10.1016/0304-4165(92)90082-6.

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30

Todd, M. M., B. Wu, M. Maktabi, B. J. Hindman, and D. S. Warner. "Cerebral blood flow and oxygen delivery during hypoxemia and hemodilution: role of arterial oxygen content." American Journal of Physiology-Heart and Circulatory Physiology 267, no. 5 (November 1, 1994): H2025—H2031. http://dx.doi.org/10.1152/ajpheart.1994.267.5.h2025.

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To determine the role of arterial O2 content (CaO2) in the cerebral blood flow (CBF) responses to hypoxemia and hemodilution, CaO2 was progressively reduced from approximately 18 to approximately 6 ml O2/dl in normocapnic, normothermic, pentobarbital-anesthetized rabbits. This was done either by reducing PaO2 (hypoxemia, minimum PaO2 approximately 26 mmHg) or arterial hematocrit (isovolemic hemodilution with hetastarch, minimum hematocrit approximately 14%) while CBF was measured with radioactive microspheres. As CaO2 decreased, CBF increased in both groups but was greater in hypoxemic animals

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31

Smith, K. M., and D. A. Newnham. "Near-infrared absorption cross sections and integrated absorption intensities of molecular oxygen (O2, O2-O2, and O2-N2)." Journal of Geophysical Research: Atmospheres 105, no. D6 (March 1, 2000): 7383–96. http://dx.doi.org/10.1029/1999jd901171.

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32

Vadapalli, Arjun, Roland N. Pittman, and Aleksander S. Popel. "Estimating oxygen transport resistance of the microvascular wall." American Journal of Physiology-Heart and Circulatory Physiology 279, no. 2 (August 1, 2000): H657—H671. http://dx.doi.org/10.1152/ajpheart.2000.279.2.h657.

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The problem of diffusion of O2 across the endothelial surface in precapillary vessels and its utilization in the vascular wall remains unresolved. To establish a relationship between precapillary release of O2 and vascular wall consumption, we estimated the intravascular flux of O2 on the basis of published in vivo measurements. To interpret the data, we utilized a diffusion model of the vascular wall and computed possible physiological ranges for O2 consumption. We found that many flux values were not consistent with the diffusion model. We estimated the mitochondrial-based maximum O2 consump

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33

Nunn, J. F., K. Makita, and B. Royston. "Validation of oxygen consumption measurements during artificial ventilation." Journal of Applied Physiology 67, no. 5 (November 1, 1989): 2129–34. http://dx.doi.org/10.1152/jappl.1989.67.5.2129.

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We describe a system for the absolute calibration of indirect calorimeters, under the conditions of artificial ventilation and increased inspired O2 concentration, in which butane, at a measured flow rate, is burned downstream of an artificial lung. One milliliter of butane requires 6.4 ml O2 for its combustion, and the respiratory quotient is 0.615. With the closed-circuit O2-replenishment method there was no significant systematic error in the measurement of either O2 consumption or CO2 output and a random error with a SD of 8.3 ml/min for O2 consumption and 6.3 ml/min for CO2 output. There

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34

Raddatz, E., M. Servin, and P. Kucera. "Oxygen uptake during early cardiogenesis of the chick." American Journal of Physiology-Heart and Circulatory Physiology 262, no. 4 (April 1, 1992): H1224—H1230. http://dx.doi.org/10.1152/ajpheart.1992.262.4.h1224.

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Oxidative metabolism of the isolated embryonic heart of the chick has been determined using a spectrophotometric technique allowing global as well as localized micromeasurements of the O2 uptake. Entire hearts, excised from embryos of 10 somites (primordia fused, stage 10 HH) and 40 somites (S shaped, stage 20 HH) were placed in a special chamber under controlled metabolic conditions where they continued to beat spontaneously and regularly. During the 32 h of development, the O2 consumption of the whole heart increased from 0.9 +/- 0.1 to 5.3 +/- 0.8 nmol O2/h. These values corrected for prote

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35

Aaron, E. A., B. D. Johnson, C. K. Seow, and J. A. Dempsey. "Oxygen cost of exercise hyperpnea: measurement." Journal of Applied Physiology 72, no. 5 (May 1, 1992): 1810–17. http://dx.doi.org/10.1152/jappl.1992.72.5.1810.

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To quantitate the O2 cost of maximal exercise hyperpnea, we required eight healthy adult subjects to mimic, at rest, the important mechanical components of submaximal and maximal exercise hyperpnea. Expired minute ventilation (VE), transpulmonary and transdiaphragmatic (Pdi) pressures, and end-expiratory lung volume (EELV) were measured during exercise at 70 and 100% of maximal O2 uptake. At rest, subjects were given visual feedback of their exercise transpulmonary pressure-tidal volume loop (WV), breathing frequency, and EELV, which they mimicked repeatedly for 5 min per trial over several tr

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36

Minaev, Boris. "Photochemistry and Spectroscopy of Singlet Oxygen in Solvents. Recent Advances which Support the Old Theory." Chemistry & Chemical Technology 10, no. 4s (December 25, 2016): 519–30. http://dx.doi.org/10.23939/chcht10.04si.519.

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Molecular oxygen is a paramagnetic gas with the triplet O2( ) ground state which exhibits just sluggish chemical reactivity in the absence of radical sources. In contrast, the excited metastable singlet oxygen O2( ) is highly reactive; it can oxygenate organic molecules in a wide range of specific reactions which differ from those of the usual triplet oxygen of the air. This makes the singlet oxygen an attractive reagent for new synthesis and even for medical treatments in photodynamic therapy. As an important intermediate O2( ) has attracted great attention of chemists during half-century stu

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37

Hoogakker, B. A. A., D. J. R. Thornalley, and S. Barker. "Millennial changes in North Atlantic oxygen concentrations." Biogeosciences Discussions 12, no. 15 (August 13, 2015): 12947–73. http://dx.doi.org/10.5194/bgd-12-12947-2015.

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Abstract. Glacial–interglacial changes in bottom water oxygen concentrations [O2] in the deep Northeast Atlantic have been linked to decreased ventilation relating to changes in ocean circulation and the biological pump (Hoogakker et al., 2015). In this paper we discuss seawater [O2] changes in relation to millennial climate oscillations in the North Atlantic ocean over the last glacial cycle, using bottom water [O2] reconstructions from 2 cores: (1) MD95-2042 from the deep northeast Atlantic (Hoogakker et al., 2015), and (2) ODP 1055 from the intermediate northwest Atlantic. Deep northeast At

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38

Yamada, Y., A. Ito, K. Kuono, H. Yoshida, and Y. Kobayashi. "Laser deposition of iron in oxygen atmosphere." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 429–33. http://dx.doi.org/10.1524/rcpr.2011.0078.

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AbstractIron oxide films were produced by pulsed laser deposition (PLD) of 57Fe metal in an oxygen atmosphere and their compositions were studied by Mössbauer spectroscopy. The effects of gas-phase reactions were investigated by varying the pressure of O2 gas or an O2/Ar gas mixture. When PLD was performed in a high-pressure O2 atmosphere, the main product in the film was trivalent iron oxide particles. When the O2 pressure was reduced, hematite Fe2O3 became dominant in the film, while wüstite FeO was produced at very low O2 pressures. PLD in an O2/Ar gas mixture produced films of trivalent ir

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39

Torres Filho, Ivo P., Bruce D. Spiess, Roland N. Pittman, R. Wayne Barbee, and Kevin R. Ward. "Experimental analysis of critical oxygen delivery." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 3 (March 2005): H1071—H1079. http://dx.doi.org/10.1152/ajpheart.00884.2004.

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Systemic variables were evaluated with respect to O2 delivery to test the hypothesis that critical O2 delivery and critical Hb can be estimated by multiple variables collected simultaneously. Rats were subjected to transfusion with either fresh or stored blood and then subjected to stepwise isovolemic hemodilution. Critical levels were measured by the dual-regression method from plots of systemic variables against O2 delivery and Hb. Delivery was calculated from cardiac index and arterial O2 content. We found that 1) after hemodilution, O2 delivery changed in a nonlinear relationship with Hb;

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40

Gutierrez, G., A. R. Warley, and D. R. Dantzker. "Oxygen delivery and utilization in hypothermic dogs." Journal of Applied Physiology 60, no. 3 (March 1, 1986): 751–57. http://dx.doi.org/10.1152/jappl.1986.60.3.751.

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Hypothermia produces a decrease in metabolic rate that may be beneficial under conditions of reduced O2 delivery (Do2). Another effect of hypothermia is to increase the affinity of hemoglobin for O2, which can adversely affect the release of O2 to the tissues. To determine the overall effect of hypothermia on the ability of the peripheral tissues to extract O2 from blood, we compared the response to hypoxemia of hypothermic dogs (n = 8) and of normothermic controls (n = 8). The animals were anesthetized, mechanically ventilated, and paralyzed to prevent shivering. The inspired concentration of

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41

Bender, Renar J., Jeffrey K. Brecht, Steven A. Sargent, and Donald J. Huber. "Mango Tolerance to Reduced Oxygen Levels in Controlled Atmosphere Storage." Journal of the American Society for Horticultural Science 125, no. 6 (November 2000): 707–13. http://dx.doi.org/10.21273/jashs.125.6.707.

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`Haden' and `Tommy Atkins' mangoes (Mangifera indica L.) were stored in air, 2, 3, 4 or 5 kPa O2 plus N2, or 25 kPa CO2 plus air for 14 days at 15 °C or 21 days at 12 °C, respectively, then in air for 5 days at 20 °C to determine their tolerance to reduced O2 levels for storage times encountered in typical marine shipments. All low O2 treatments reduced mature green mango respiration (CO2 production), however, elevated ethanol production occurred in 2 and 3 kPa O2 storage, with the levels two to three times higher in `Tommy Atkins' than `Haden'. In contrast, `Haden' fruit at the onset of the c

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42

Hoogakker, B. A. A., D. J. R. Thornalley, and S. Barker. "Millennial changes in North Atlantic oxygen concentrations." Biogeosciences 13, no. 1 (January 15, 2016): 211–21. http://dx.doi.org/10.5194/bg-13-211-2016.

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Abstract. Glacial–interglacial changes in bottom water oxygen concentrations [O2] in the deep northeast Atlantic have been linked to decreased ventilation relating to changes in ocean circulation and the biological pump (Hoogakker et al., 2015). In this paper we discuss seawater [O2] changes in relation to millennial climate oscillations in the North Atlantic over the last glacial cycle, using bottom water [O2] reconstructions from 2 cores: (1) MD95-2042 from the deep northeast Atlantic (Hoogakker et al., 2015) and (2) ODP (Ocean Drilling Program) Site 1055 from the intermediate northwest Atla

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43

Kedem, J., B. A. Acad, and H. R. Weiss. "Pacing during reperfusion elevates regional myocardial oxygen consumption." American Journal of Physiology-Heart and Circulatory Physiology 259, no. 3 (September 1, 1990): H872—H878. http://dx.doi.org/10.1152/ajpheart.1990.259.3.h872.

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Reperfusion after 2 h of coronary artery occlusion has been shown to result in depressed coronary blood flow to the reperfused region and elevated regional myocardial extraction. This suggests that reperfused myocardium, even after 4 h of reperfusion, possesses limited flow and O2 consumption reserves. We studied the capacity of reperfused myocardium to elevate regional blood flow and regional O2 consumption in response to sustained increased O2 demand, produced by atrial pacing. Two groups of anesthetized open-chest dogs were subjected to 2 h of left anterior descending coronary artery occlus

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44

Bender, P. R., B. M. Groves, R. E. McCullough, R. G. McCullough, S. Y. Huang, A. J. Hamilton, P. D. Wagner, A. Cymerman, and J. T. Reeves. "Oxygen transport to exercising leg in chronic hypoxia." Journal of Applied Physiology 65, no. 6 (December 1, 1988): 2592–97. http://dx.doi.org/10.1152/jappl.1988.65.6.2592.

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Residence at high altitude could be accompanied by adaptations that alter the mechanisms of O2 delivery to exercising muscle. Seven sea level resident males, aged 22 +/- 1 yr, performed moderate to near-maximal steady-state cycle exercise at sea level in normoxia [inspired PO2 (PIO2) 150 Torr] and acute hypobaric hypoxia (barometric pressure, 445 Torr; PIO2, 83 Torr), and after 18 days' residence on Pikes Peak (4,300 m) while breathing ambient air (PIO2, 86 Torr) and air similar to that at sea level (35% O2, PIO2, 144 Torr). In both hypoxia and normoxia, after acclimatization the femoral arter

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45

Wang, Shiow Y., and Hongjun Jiao. "367 Scavenging Capacity of Active Oxygen Species in Blackberry." HortScience 35, no. 3 (June 2000): 455E—455. http://dx.doi.org/10.21273/hortsci.35.3.455e.

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The effect of blackberries (Rubus sp.) genotypes on antioxidant activities against superoxide radicals (O2–), hydrogen peroxide (H2O2), hydroxyl radicals (OH), and singlet oxygen (O,), was evaluated. The results were expressed as percent inhibition of active oxygen species production in the presence of fruit juice. The active oxygen radical absorbance capacity (ORAC) value referred to the net protection in the presence of fruit juice, and was expressed as micromoles of α-tocopherol, ascorbate, α-tocopherol, and β-carotene equivalents per 10 g of fresh weight for O2–, H2O2, OH, and O2, respecti

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46

Linsey, G. A., and D. C. Lasenby. "Comparison of Summer and Winter Oxygen Consumption Rates in a Temperate Dimictic Lake." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 10 (October 1, 1985): 1634–39. http://dx.doi.org/10.1139/f85-204.

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In a temperate dimictic lake in southern Ontario, the winter rate of oxygen loss determined from oxygen profiles differed considerably from the summer hypolimnetic rate, although the sediment oxygen demand (SOD) and water column oxygen demand (WOD) did not change significantly (SOD: winter = 0.018 mg O2∙L−1∙d−1, summer = 0.020 mg O2∙L−1∙d−1; WOD: winter = 0.032 mg O2∙L−1∙d−1, summer = 0.027 mg O2∙L−1∙d−1). In summer, the sum of SOD and WOD (0.047 mg O2∙L−1∙d−1) closely approximated the hypolimnetic deficit (0.040 mg O2∙L−1∙d−1), but in winter, SOD plus WOD (0.050 mg O2∙L−1∙d−1) greatly overest

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47

Kasil, Abdelsalam, Sebastien Giraud, Pierre Couturier, Akbar Amiri, Jerome Danion, Gianluca Donatini, Xavier Matillon, Thierry Hauet, and Lionel Badet. "Individual and Combined Impact of Oxygen and Oxygen Transporter Supplementation during Kidney Machine Preservation in a Porcine Preclinical Kidney Transplantation Model." International Journal of Molecular Sciences 20, no. 8 (April 23, 2019): 1992. http://dx.doi.org/10.3390/ijms20081992.

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Marginal kidney graft preservation in machine perfusion (MP) is well-established. However, this method requires improvement in order to mitigate oxidative stress during ischemia-reperfusion, by using oxygenation or an O2 carrier with anti-oxidant capacities (hemoglobin of the marine worm; M101). In our preclinical porcine (pig related) model, kidneys were submitted to 1h-warm ischemia, followed by 23 h hypothermic preservation in Waves® MP before auto-transplantation. Four groups were studied: W (MP without 100%-O2), W-O2 (MP with 100%-O2; also called hyperoxia), W-M101 (MP without 100%-O2 + M

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48

Baskerville, Tracey A., Graeme A. Deuchar, Christopher McCabe, Craig A. Robertson, William M. Holmes, Celestine Santosh, and I. Mhairi Macrae. "Influence of 100% and 40% Oxygen on Penumbral Blood Flow, Oxygen Level, and T*2-Weighted MRI in a Rat Stroke Model." Journal of Cerebral Blood Flow & Metabolism 31, no. 8 (May 11, 2011): 1799–806. http://dx.doi.org/10.1038/jcbfm.2011.65.

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Accurate imaging of the ischemic penumbra is a prerequisite for acute clinical stroke research. T*2 magnetic resonance imaging (MRI) combined with an oxygen challenge (OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. However, inducing OC with 100% O2 induces sinus artefacts on human scans and influences cerebral blood flow (CBF), which can affect T*2 signal. Therefore, we investigated replacing 100% O2 OC with 40% O2 OC (5 minutes 40% O2 versus 100% O2) and determined the effects on blood pressure (BP), CBF, tissue pO2, and T*2 signal change in presumed penu

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49

Zhang, Yong Feng, Xiang Yun Chen, Quan Zhou, Qian Cheng Zhang, and Chun Ping Li. "Combustion Kinetic Analysis of Lignite in Different Oxygen Concentration." Advanced Materials Research 884-885 (January 2014): 37–40. http://dx.doi.org/10.4028/www.scientific.net/amr.884-885.37.

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Combustion behavior of indigenous lignite in oxygen-enriched conditions was investigated by using thermogravimetric analyzer (TGA). Combustion tests were carried out in different oxygen concentration (21%O2/79%N2, 30%O2/70%N2, 40%O2/60%N2, 50%O2/50%N2, 60%O2/40%N2, 70%O2/30%N2). Then get the characteristic temperatures. . The model-fitting mathematical approach was used to evaluated the kinetic triplet (f (α),E,A) through Gorbatchev method. The combustion stages were divided into the early combustion stage and the later combustion stage. The calculation showed that the kinetics parameters high

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50

Chung, Youngran. "Oxygen reperfusion is limited in the postischemic hypertrophic myocardium." American Journal of Physiology-Heart and Circulatory Physiology 290, no. 5 (May 2006): H2075—H2084. http://dx.doi.org/10.1152/ajpheart.00619.2005.

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Studies have shown that hypertrophied hearts are unusually vulnerable to ischemia. Compromised O2 supply has been postulated as a possible explanation for this phenomenon on the basis of elongated O2 diffusion distance and altered coronary vasculature found in hypertrophied myocardium. To examine the postulate, perfused heart experiments followed the metabolic and functional responses of hypertrophic myocardium to ischemia. 1H/31P NMR was used to measure cellular oxygenation and energy level during ischemia-reperfusion. The left ventricles from spontaneously hypertensive rats (SHR) were enlarg

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