Cellular oxygen

The goal of oxygen therapy is to maintain Pao2 above 60 mm Hg (8 kPa) or Sao2 above 90% in order to prevent tissue hypoxia and preserve cellular oxygenation.1 Increasing the Pao2 much further confers little added benefit and may increase the risk of C02 retention, which may lead to respiratory acidosis. An arterial blood gas should be obtained after 1 to 2 hours to assess for hypercapnia. 

The experimental set-up for cellular oxygen measurements (p02) consists of following components p02 measuring micro chamber (volume 0.6 microliter), polarographic microelectrode, water-bath for constant temperature, chemical microsensor connected to a strip-chart recorder and gas calibration unit. 

Cellular oxygen consumption. In a preliminary test series 9 p02... 

Cellular oxygen is bound by myoglobin molecules that store it until it is required for metabolic action, where upon they release it to other acceptors. Hemoglobin has a additional function, however, and that is to carry CO2 back to the lungs this is done by certain amino acid side chains, and the heme groups are not directly involved. Because the circumstances under which Hb and Mb are required to bind and release O2 are very different, the two substances have quite different binding constants as a function of O2 partial pressure (Fig.). 

Cyanide Binds to cytochrome, blocks cellular oxygen use Headache, nausea, vomiting, syncope, seizures, coma... 

Oshino, N, Chance, B. A survey of factors involved in cellular oxygen toxicity. In Biochemical and Medical Aspects of Active Oxygen (Hayaishi, O.. Asada, K., eds.), Baltimore-London-Tokyo, University Park Press, 1977, pp. 191-207... 

Porter RK (2001) Allometry of mammalian cellular oxygen consumption. Cell Mol Life Sci 58 815-822... 

Wang, G.L., B-H. Jiang, E.A. Rue, and G.L. Semenza (1995). Hypoxia inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular oxygen tension. Proc. Natl. Acad. Sci. USA 92 5510-5514. 

Cash TP, Pan Y, Simon MC. Reactive oxygen species and cellular oxygen sensing. Free Radic. Biol. Med. 2007 43 1219-1225. Gorlach A, Kietzmann T. Superoxide and derived reactive oxygen species in the regulation of hypoxia-inducible factors. Methods Enzymol. 2007 435 421-446. 

McDonough MA, Li V, Flashman E, Chowdhury R, Mohr C, Lienard BM, Zondlo J, Oldham NJ, Clifton IJ, Lewis J, McNeill LA, Kurzeja RJ, Hewitson KS, Yang E, Jordan S, Syed RS, Schofield CJ. Cellular oxygen sensing crystal structure of hypoxia-inducible factor prolyl hydroxylase (PHD2). Proc. Natl. Acad. Sci. U.S.A. 2006 103 9814-9819. 

Mitochondria constitute the main source with regard to oxygen concentration in the cell. This especially applies to the respiratory chain in the inner mitochondrial membrane. Moreover, the additional formation of cellular oxygen takes place through the transport of electrons in the nuclear membranes and microsomes. Eosinophilic... 

Continued reduction or cessation in the formation of oxygen radicals (especially in the area of the mitochondria, nuclear membranes or microsomes) is eventually fatal to the cell. An uncontrolled increase in the cellular formation of superoxide dismutase (as is found in mental disease, trisomy 21, etc.) may also entail dangerous disturbances in the cellular oxygen balance. Moreover, a change in the physicochemical properties of superoxide dismutase under pathological conditions, which may lead to reduced enzyme activity and altered cell compartments, is being discussed as a further influencing factor. 

Once Kitt is known, the cellular oxygen consumption rate, qX, can be measured under culture conditions. The mass balance for oxygen in a batch reactor with cells is given by ... 

The effects of berbamine on energy metabolism in isolated rat alveolar type II cells (cells which play a critical role in the maintenance of normal lung function) were studied. Incubation of type II cells with berbamine produced a reduction in cellular ATP content, but there was no effect of the alkaloid on cellular oxygen consumption. Berbamine produced an increase in internal calcium levels of type II cells, and incubation of the cells with calcium ionophore, 4-bromo A-23187, led to increased amounts of cellular calcium and reductions in ATP levels, with no effect on oxygen consumption. Exposure of isolated lung mitochondria to calcium produced a concentration-dependent reduction in ATP synthesis with no effect on mitochondrial oxygen... 

Hypoxia inducible factor 1 alpha (HIF-la) is a transcription factor that responds directly to intracellular levels of oxygen. When levels become reduced due to mismatch of cellular oxygen supply and... 

A major cause of acidosis that occurs during inadequate cellular oxygen delivery is continual hydrolysis of the available supply of ATP that releases protons ... 

Cellular oxygen utilization decreases as a function of age and the ATP generating capacity of the cell is a function of age. The attenuation of ATP synthesis is associated with an age-related increase in somatic mtDNA damage in postmitotic tissue. The normal decline in ATP generating capability may facilitate disease occurrence when it is associated with an inherited oxidative phosphorylation mutation. 

Acker T, Acker H. 2004. Cellular oxygen sensing need in CNS function Physiological and pathological implications. J Exp Biol 207 3171-3188. 

Chandel NS, Schumacker PT. 2000. Cellular oxygen sensing by mitochondria Old questions, new insight. J Appl Physiol 88 1880-1889. 

Fandrey J, Gorr TA, Gassmann M. 2006. Regulating cellular oxygen sensing by hydroxylation. Cardiovasc Res 71 642-651. 

Guzy RD, Hoyos B, Robin E, Chen H, Liu LP, et al. 2005. Mitochondrial complex 111 is required for hypoxia-induced ROS production and cellular oxygen sensing. Cell Metab 1 401-408. 

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