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Summary Bilateral lesions of the suprachiasmatic nucleus of the hypothalamus of rats abolished circadian rhythms of oxygen consumption and of the respiratory quotient (RQ). The RQ remained constant at a level intermediate between the maximum (about 1.0) and minimum (about 0.9) values in control animals. 相似文献
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Bilateral lesions of the suprachiasmatic nucleus of the hypothalamus of rats abolished circadian rhythms of oxygen consumption and of the respiratory quotient (RQ). The RQ remained constant at a level intermediate between the maximum (about 1.0) and minimum (about 0.9) values in control animals. 相似文献
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A. Mansouri 《Cellular and molecular life sciences : CMLS》1981,37(1):95-96
Summary It is suggested that although the high oxygen affinity hemoglobin (Hb LR) (143(H21)HisGln) with stabilization of R quaternary conformation is not more susceptible to the oxidizing effect of nitrites in vitro, in an in vivo situation where hemoglobin is partly deoxygenated, it might be more susceptible to methemoglobin formation due to higher oxidation and lower reduction rate.Supported by NIH grant No. 5 RO1 AM 20181-02 and VA grant No. 5455-002.Acknowledgments. The technical assistance of Ms Carol A. Perry is highly appreciated. 相似文献
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Allometry of mammalian cellular oxygen consumption 总被引:3,自引:0,他引:3
R.K. Porter 《Cellular and molecular life sciences : CMLS》2001,58(5-6):815-822
In the 1930s, Max Kleiber and Samuel Brody established that the interspecies correlation between mammalian body mass and metabolic rate (αM0.75) cannot be explained (solely) by whole body surface area (αM0.66) to volume ratios. Metabolic considerations must also be taken into account. Decreases in the proportion of visceral organ mass to whole body mass can account for some of the whole body metabolic differences. However, superimposed upon these anatomical differences, the metabolism of tissues and cells has been demonstrated to decrease with increasing body mass. These decreases in oxygen consumption rates (with increasing body mass) in cells and tissues can be explained by a decrease in ATP turnover and mitochondrial density and an increase in mitochondrial functional efficiency (decrease in proton leak). The majority of the proton leak differences reflect differences in mitochondrial inner membrane surface area. Indeed, liver metabolism correlates directly with liver mitochondrial inner membrane surface area. Apart from being a significant contributor (~25 %) to basal metabolism, mitochondrial proton leak is a major factor determining the differences in basal metabolism between mammals of different body mass. Received 31 May 2000; received after revision 2 October 2000; accepted 14 November 2000 相似文献
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G Ferretti 《Experientia》1990,46(11-12):1188-1194
The present paper discusses the factors affecting maximal O2 consumption (VO2max) in hypoxia (4300 m above sea level) along the following lines: 1) In acute hypoxia, the fractional limitation to VO2max imposed by circulatory O2 transport (FQ') is 50%, instead of 70% as in normoxia. This is due to the increase in the blood O2 transport coefficient (beta b) as PO2 decreases, as a consequence of the sigmoidal shape of the O2 dissociation curve of hemoglobin. The remaining 50% is assumed to be equally partitioned between tissue O2 transfer (Ft') and mitochondria O2 utilization (Fm'). 2) In chronic hypoxia, FQ' = 0.45, Ft' = 0.20 and Fm' = 0.35, as a consequence of reduced muscle fiber size and muscle mitochondrial density following acclimatization. 3) The relationship between VO2max and PIO2 in both acute and chronic hypoxia reflects the O2 dissociation curve. 4) Acclimatization to chronic hypoxia does not have the function of preserving VO2max. 相似文献
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Inhaled allergens from house dust, mites or animal danders activate human complement in vitro by engaging the C1-component
through a non-antibody-dependent mechanism. These earlier findings are extended by showing that the allergenic components
in extracts of Parietaria pollen are almost equally potent complement activators as those from house dust or mites. Spectroscopic evidence indicates
that haemolytic complement consumption by the Parietaria allergens and their enzymic fragments is most likely related to post-translational side-chains comprising flavonoid derivatives.
These adsorbed and/or peptide-bound tannin-like structures may also explain the exceptional stability of the high- and low-molecular
mass allergenic components in Parietaria pollen extracts.
Received 12 November 1996; received after revision 12 December 1996; accepted 17 December 1996 相似文献
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Summary The oxygen consumption of rat small intestine in vitro is influenced by the anions, chloride and bicarbonate, as well as by sodium.USPHS support: Grant number AM13240 and Award number AM70199. 相似文献
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Summary Resting oxygen consumption of the vascularly isolated gracilis anticus muscle of the rat perfused by natural circulation via the femoral artery with diluted or undiluted blood depends on oxygen delivery (the product of flow rate and arterial oxygen concentration-DO2) only when DO2 falls below 16 l/min/g. 相似文献
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R. D. Roer V. G. Sidelyova R. W. Brauer G. I. Galazii 《Cellular and molecular life sciences : CMLS》1984,40(7):771-773
Summary Rates of oxygen consumption in shallow dwelling cottid fish from Lake Baikal were unaffected by a change in pressure from 11 to 51 ata. The metabolic rate of deep cottids decreased by 72% when the pressure was decreased by 50% from that corresponding to habitat depth. Recovery from decreased pressures was incomplete in deep fish, suggesting that measurements of
in deep dwelling fish in the literature may underestimate actual rates.Acknowledgments. Thanks are due to the US and USSR Academies of Sciences and the crew of the Titov. Support was provided by grants from The National Geographic Society, The George Baker Trust, The Max and Victoria Dreyfus Foundation, and The Griffis Foundation, Inc. 相似文献
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W. C. Eisenberg K. Taylor L. J. Schiff 《Cellular and molecular life sciences : CMLS》1984,40(5):514-515
Summary Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen,1O2, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology.Acknowledgments. The authors acknowledge helpful conversations with Professor R.W. Murray of the University of Missouri (St. Louis). We would like to thank the National Institute of Environmental Health Sciences for supporting this work through Public Health Grant 1-RO1-ESO1-O1A1-PHTB. 相似文献
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Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen, O2, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology. 相似文献
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E Adkins-Regan 《Science progress》1985,69(276):551-565
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R. M. Gesinski J. H. Morrison J. R. Toepfer Ch. V. Riley 《Cellular and molecular life sciences : CMLS》1970,26(4):379-381
Zusammenfassung Der Sauerstoffverbrauch von Kno chenmarkzellen der Ratte in Thyrodelösung (verschiedene Konzentrationen und Molekulargewichte) wurde unter sucht. Zwischen Sauerstoffverbrauch und Viskosität des suspendierenden Mediums oder des Volumens der Zellen konnten keine Beziehungen gefunden werden. Mögliche physiologische Dextranwirkungen auf die Zellaktivität werden diskutiert. 相似文献