scholarly journals Physiology and Pathophysiology of Oxygen Sensitivity

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1114
Author(s):  
Robert S. Fitzgerald ◽  
Asuncion Rocher
Keyword(s):  
Carotid Body ◽  
Respiratory Diseases ◽  
Oxygen Demand ◽  
Oxygen Sensors ◽  
Oxygen Availability ◽  
Oxygen Sensitivity ◽  
Demand And Supply ◽  
Essential Requirement ◽  
O2 Transport ◽  
Molecular Aspects

Oxygen is an essential requirement for metabolism in mammals and many other animals. Therefore, pathways that sense a reduction in available oxygen are critical for organism survival. Higher mammals developed specialized organs to detect and respond to changes in O2 content to maintain gas homeostasis by balancing oxygen demand and supply. Here, we summarize the various oxygen sensors that have been identified in mammals (carotid body, aortic bodies, and astrocytes), by what mechanisms they detect oxygen and the cellular and molecular aspects of their function on control of respiratory and circulatory O2 transport that contribute to maintaining normal physiology. Finally, we discuss how dysregulation of oxygen availability leads to elevated signalling sensitivity in these systems and may contribute to the pathogenesis of chronic cardiovascular and respiratory diseases and many other disorders. Hence, too little oxygen, too much oxygen, and a malfunctioning sensitivity of receptors/sensors can create major pathophysiological problems for the organism.

Apparent diffusion time of oxygen from blood to tissue in rat cerebral cortex: implication for tissue oxygen dynamics during brain functions

2007 ◽  
Vol 103 (4) ◽  
pp. 1352-1358 ◽  
Author(s):  
Kazuto Masamoto ◽  
Jeff Kershaw ◽  
Masakatsu Ureshi ◽  
Naosada Takizawa ◽  
Hirosuke Kobayashi ◽  
...  
Keyword(s):  
Time Course ◽  
Oxygen Demand ◽  
Excess Demand ◽  
Tissue Oxygen ◽  
Doppler Flowmetry ◽  
Demand And Supply ◽  
Brain Functions ◽  
Apparent Diffusion ◽  
Time Required ◽  
Stimulus Length

To investigate the dynamics of tissue oxygen demand and supply during brain functions, we simultaneously recorded Po2 and local cerebral blood flow (LCBF) with an oxygen microelectrode and laser Doppler flowmetry, respectively, in rat somatosensory cortex. Electrical hindlimb stimuli were applied for 1, 2, and 5 s to vary the duration of evoked cerebral metabolic rate of oxygen (CMRO2). The electrical stimulation induced a robust increase in Po2 (4–9 Torr at peak) after an increase in LCBF (14–26% at peak). A consistent lag of ∼1.2 s (0.6–2.3 s for individual animals) in the Po2 relative to LCBF was found, irrespective of stimulus length. It is argued that the lag in Po2 was predominantly caused by the time required for oxygen to diffuse through tissue. During brain functions, the supply of fresh oxygen further lagged because of the latency of LCBF onset (∼0.4 s). The results indicate that the tissue oxygen supports excess demand until the arrival of fresh oxygen. However, a large drop in Po2 was not observed, indicating that the evoked neural activity demands little extra oxygen or that the time course of excess demand is as slow as the increase in supply. Thus the dynamics of Po2 during brain functions predominantly depend on the time course of LCBF. Possible factors influencing the lag between demand and supply are discussed, including vascular spacing, reactivity of the vessels, and diffusivity of oxygen.

scholarly journals Exploring the oxygen sensitivity of wetland soil carbon mineralization

2019 ◽  
Vol 15 (1) ◽  
pp. 20180407 ◽  
Author(s):  
Samantha K. Chapman ◽  
Matthew A. Hayes ◽  
Brendan Kelly ◽  
J. Adam Langley
Keyword(s):  
Soil Carbon ◽  
Coastal Wetlands ◽  
Carbon Mineralization ◽  
Oxygen Availability ◽  
Blue Carbon ◽  
Oxygen Sensitivity ◽  
Wetland Soil ◽  
Soil Oxygen ◽  
Precise Understanding ◽  
Wide Range

Soil oxygen availability may influence blue carbon, which is carbon stored in coastal wetlands, by controlling the decomposition of soil organic matter. We are beginning to quantify soil oxygen availability in wetlands, but we lack a precise understanding of how oxygen controls soil carbon dynamics. In this paper, we synthesize existing data from oxic and anoxic wetland soil incubations to determine how oxygen controls carbon mineralization. We define the oxygen sensitivity of carbon mineralization as the ratio of carbon mineralization rate in oxic soil to this rate in anoxic soil, such that higher values of this ratio indicate greater sensitivity of carbon mineralization to oxygen. The estimates of oxygen sensitivity we derived from existing literature show a wide range of ratios, from 0.8 to 33, across wetlands. We then report oxygen sensitivities from an experimental mesocosm we developed to manipulate soil oxygen status in realistic soils. The variation in oxygen sensitivity we uncover from this systematic review and experiment indicates that Earth system models may misrepresent the oxygen sensitivity of carbon mineralization, and how it varies with context, in wetland soils. We suggest that altered soil oxygen availability could be an important driver of future blue carbon storage in coastal wetlands.

scholarly journals Calibration and Stability of Oxygen Sensors on Autonomous Floats

2013 ◽  
Vol 30 (8) ◽  
pp. 1896-1906 ◽  
Author(s):  
Eric A. D'Asaro ◽  
Craig McNeil
Keyword(s):  
Temperature Compensation ◽  
Decay Constant ◽  
Oxygen Sensors ◽  
Oxygen Sensitivity ◽  
Partial Pressure Of Oxygen ◽  
Water Sensor ◽  
Standard Pressure ◽  
Calibration Accuracy

Abstract The calibration accuracy and stability of three Aanderaa 3835 optodes and three Sea-Bird Electronics SBE-43 oxygen sensors were evaluated over four years using in situ and laboratory calibrations. The sensors were mostly in storage, being in the ocean for typically only a few weeks per year and operated for only a few days per year. Both sensors measure partial pressure of oxygen, or equivalently saturation at standard pressure; results are expressed in this variable. It is assumed that sensor drift occurs in the oxygen sensitivity of the sensors, not the temperature compensation; this is well justified for the SBE-43 based on multiple calibrations. Neither sensor had significant long-term drift in output when sampling anoxic water. Sensor output at 100% saturation differed from the factory calibrations by up to ±6% (averaging −2.3% ± 3%) for the SBE-43 and up to −12.6% for the optodes. The optode output at 100% saturation is well described by a single decaying exponential with a decay constant of approximately 2 yr and an amplitude of 28%. The mechanism of this drift is unknown but is not primarily due to sensor operation. It may be different from that experienced by sensors continuously deployed in the ocean. Thus, although the optodes in this study did not have a stable calibration, their drift was stable and, once calibrated, allowed optode and SBE-43 pairs mounted on the same autonomous floats to be calibrated to an accuracy of ±0.4% over a 4-yr period.

scholarly journals A prospective observational study on assessment of types of shock in children and requirement of inotropes in treatment of shock in tertiary care hospital

2021 ◽  
Vol 8 (5) ◽  
pp. 835
Author(s):  
Jhansi Rani Kotha ◽  
Hari Krishna Kothapally ◽  
Sai Chand Pinnoju ◽  
Sudheer Kumar
Keyword(s):  
Septic Shock ◽  
Mortality Rate ◽  
Cardiogenic Shock ◽  
Early Recognition ◽  
Tertiary Care ◽  
Hypovolemic Shock ◽  
Oxygen Demand ◽  
Tissue Perfusion ◽  
Care Hospital ◽  
Demand And Supply

Background: Shock is a state of impaired tissue perfusion which result in an imbalance between oxygen demand and supply. This reduction in effective tissue perfusion causes insufficient or improper delivery and distribution of oxygen and nutrients. There is sparse date regarding epidemiology of shock in paediatrics. In this study we were aimed to assess the types of shock and treatment of shock with Inotropes.Methods: Children of age 1 month to 12 years with a clinical diagnosis of shock were included.Results: Out of 155 children admitted with shock 72.2% had septic shock, 25.8% had hypovolemic shock, 1.2% had cardiogenic shock, 0.6% had dengue shock. In this study the mortality rate was 8.39% of total patients. The mortality rate of septic shock, hypovolemic shock, cardiogenic shock was 84%, 7.69%, 7.69% respectively. 74.33% of patients were treated with two Inotropes, 5.3% were treated with more than two Inotropes, 11.5% were treated with single Inotropes and 0.88% was treated with no inotrope.Conclusions: In the present study, among all types of shock the prevalence and mortality rate was more with Septic shock. As shock has high mortality rate in children the early recognition and patient education is required.

Some Effects of Temporary Exposure to Low Dissolved Oxygen Levels on Pacific Salmon Eggs

1958 ◽  
Vol 15 (2) ◽  
pp. 229-250 ◽  
Author(s):  
D. F. Alderdice ◽  
W. P. Wickett ◽  
J. R. Brett
Keyword(s):  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Oxygen Demand ◽  
Oxygen Availability ◽  
Oncorhynchus Keta ◽  
Hatching Rate ◽  
Oxygen Level ◽  
Low Oxygen ◽  
Low Dissolved Oxygen ◽  
Oxygen Levels

Eggs of the chum salmon (Oncorhynchus keta) were exposed to various constant levels of dissolved oxygen for a period of seven days. The procedure was repeated with fresh egg samples at various developmental stages. Temperatures were constant at 10 °C. from fertilization to hatching. Estimates of oxygen consumption uninhibited by low dissolved oxygen levels were obtained at various stages of egg development for whole eggs and also on the basis of the weight of larvae, excluding the yolk. Eggs were most sensitive to hypoxia between 100–200 Centigrade degree-days and compensated for reduced oxygen availability by reducing the oxygen demand and rate of development. Very low oxygen levels at early incubation stages resulted in the production of monstrosities. At about the time the circulatory system becomes functional the compensatory reduction in rate of growth under hypoxial conditions is reduced, but eggs no longer survive extreme hypoxial conditions. Eggs subjected to low dissolved oxygen levels just prior to hatching hatch prematurely at a rate dependent on the degree of hypoxia. The maximum premature hatching rate corresponded approximately with the median lethal oxygen level. Estimated median lethal levels rose slowly from fertilization to hatching. Oxygen consumption per egg rose from fertilization to hatching while the consumption per gram of larval tissue declined from a high to a low level at about the time of blastopore closure. Subsequently, a slight rise in the rate occurred up to a level which was more or less constant to hatching. "Critical" dissolved oxygen levels were calculated and they appear to define the oxygen level above which respiratory rate is unmodified by oxygen availability. Critical levels ranged from about 1 p.p.m. in early stages to over 7 p.p.m. shortly before hatching.

Oxygen demand and supply in cell culture

1981 ◽  
Vol 12 (4) ◽  
pp. 193-197 ◽  
Author(s):  
Robert J. Fleischaker ◽  
Anthony J. Sinskey
Keyword(s):  
Cell Culture ◽  
Oxygen Demand ◽  
Demand And Supply
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