Biochemical adaptation to environmental hypoxia

Hemoglobin ◽  
2018 ◽  
pp. 176-200
Author(s):  
Jay F. Storz
Keyword(s):  
Oxygen Affinity ◽  
Adaptive Significance ◽  
Aerobic Performance ◽  
Future Research ◽  
Physiological Mechanisms ◽  
Trade Off ◽  
Biochemical Adaptation ◽  
Arterial Blood ◽  
Environmental Hypoxia ◽  
Hemoglobin Oxygen Affinity

Chapter 8 explores mechanisms of hemoglobin adaptation to environmental hypoxia. Vertebrates living in hypoxic environments face the physiological challenge of optimizing the trade-off between oxygen loading at the respiratory surfaces and oxygen unloading in the tissue capillaries. In air-breathing and water-breathing vertebrates alike, fine-tuned adjustments in hemoglobin-oxygen affinity provide an energetically efficient means of compensating for a reduced oxygen tension of arterial blood. The adaptive significance of such changes is indicated by evolved changes in hemoglobin function in high-altitude mammals and birds, and erythrocytic acclimatization responses to environmental hypoxia in teleost fishes. An important goal for future research is to elucidate the specific physiological mechanisms by which changes in the oxygenation properties of hemoglobin translate into enhancements of whole-animal aerobic performance.

Microvascular oxygen transport: impact of a left-shifted dissociation curve

1992 ◽  
Vol 262 (2) ◽  
pp. H517-H522 ◽  
Author(s):  
J. C. Stein ◽  
M. L. Ellsworth
Keyword(s):  
Oxygen Transport ◽  
Striated Muscle ◽  
Oxygen Affinity ◽  
Capillary Network ◽  
Retractor Muscle ◽  
Hemodynamic Parameters ◽  
Arterial Blood ◽  
Hemoglobin Oxygen Affinity ◽  
The Impact

The impact of an increased hemoglobin oxygen affinity (decreased P50) on oxygen transport was evaluated in capillaries of the retractor muscle under nonhypoxic (FIo2 = 0.30 and 0.21) and hypoxic (FIo2 = 0.10) conditions in hamsters with normal oxygen affinity [control; P50 = 26.1 +/- 1.0 (SD) mmHg, n = 12] and in hamsters with an increased oxygen affinity [treated; P50 = 16.2 +/- 1.6 (SD) mmHg, n = 7] induced by chronic short-term administration of sodium cyanate. Using in vivo video microscopy and computer-aided image analysis, we determined oxygen saturation (SO2) and associated hemodynamic parameters in both arteriolar (n = 30 control, 18 treated) and venular (n = 25 control, 17 treated) capillaries. In response to hypoxia, systemic arterial PO2 decreased to 29.6 +/- 6.0 (SD) mmHg in control animals and 24.7 +/- 3.8 (SD) mmHg in treated animals associated with abrupt decreases in systemic arterial blood pressure and increases in respiratory rate. The decrease in SO2 across the capillary network during nonhypoxic ventilation was 13.3% SO2 for control animals and 11.0% SO2 for treated animals. During hypoxic ventilation, the decrease in SO2 was 9.1% SO2 in control animals and 8.7% SO2 in treated animals. Hemodynamic parameters were not significantly different in the two groups during hypoxia. Estimated end-capillary PO2 was significantly lower in the treated animals. These data indicate that an increased oxygen affinity does not provide an obvious advantage for oxygen transport during hypoxia at the level of the capillary network in resting striated muscle; however, such an advantage might become apparent in the presence of an increased metabolic rate or a more severe hypoxic challenge.

Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard, Varanus rosenbergi

2005 ◽  
Vol 288 (4) ◽  
pp. R992-R997 ◽  
Author(s):  
T. D. Clark ◽  
T. Wang ◽  
P. J. Butler ◽  
P. B. Frappell
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Oxygen Affinity ◽  
Aerobic Performance ◽  
Specific Rate ◽  
Aerobic Scope ◽  
Thermal Dependence ◽  
Hemoglobin Oxygen Affinity ◽  
Rate Of Oxygen Consumption ◽  
Metabolic Performance

The majority of information concerning the cardio-metabolic performance of varanids during exercise is limited to a few species at their preferred body temperature (Tb) even though, being ectotherms, varanids naturally experience rather large changes in Tb. Although it is well established that absolute aerobic scope declines with decreasing Tb, it is not known whether changes in cardiac output (V̇b) and/or tissue oxygen extraction, (CaO2 − Cv�[Formula: see text]), are in proportion to the rate of oxygen consumption (V̇o2). To test this, we studied six Rosenberg's goannas ( Varanus rosenbergi) while at rest and while maximally exercising on a treadmill both at 25 and 36°C. During maximum exercise both at 25 and 36°C, mass-specific rate of oxygen consumption (V̇o2kg) increased with an absolute scope of 8.5 ml min−1 kg−1 and 15.7 ml min−1 kg−1, respectively. Interestingly, the factorial aerobic scope was temperature-independent and remained at 7.0 which, at each Tb, was primarily the result of an increase in V̇bkg, governed by approximate twofold increases both in heart rate ( fH) and cardiac stroke volume (VSkg). Both at 25°C and 36°C, the increase in V̇bkg alone was not sufficient to provide all of the additional oxygen required to attain maximal V̇o2kg, as indicated by a decrease in the blood convection requirement V̇bkg/V̇o2kg; hence, there was a compensatory twofold increase in (CaO2 − [Formula: see text]). Although associated with an increase in hemoglobin-oxygen affinity, a decrease in Tb did not impair unloading of oxygen at the tissues and act to reduce (CaO2 − Cv�[Formula: see text]); both CaO2 and Cv�[Formula: see text] were maintained across Tb. The change in V̇o2kg with Tb, therefore, is solely reliant on the thermal dependence of V̇bkg. Maintaining a high factorial aerobic scope across a range of Tb confers an advantage in that cooler animals can achieve higher absolute aerobic scopes and presumably improved aerobic performance than would otherwise be achievable.

scholarly journals Effects of an allosteric hemoglobin affinity modulator on arterial blood gases and cardiopulmonary responses during normoxic and hypoxic low-intensity exercise

2020 ◽  
Vol 128 (6) ◽  
pp. 1467-1476
Author(s):  
Glenn M. Stewart ◽  
Steven Chase ◽  
Troy J. Cross ◽  
Courtney M. Wheatley-Guy ◽  
Michael J. Joyner ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Partial Pressure ◽  
Arterial Oxygen Saturation ◽  
Oxygen Affinity ◽  
Blood Gases ◽  
Submaximal Exercise ◽  
Arterial Oxygen ◽  
Arterial Blood ◽  
Hemoglobin Oxygen Affinity ◽  
Low Intensity Exercise

In humans, a novel allosteric hemoglobin-oxygen affinity modulator was administered to comprehensively examine the cardiopulmonary consequences of stabilizing a portion of the available hemoglobin in a high-oxygen affinity state during submaximal exercise in normoxia and hypoxia. Oral administration of voxelotor enhanced arterial oxygen saturation during submaximal exercise without altering oxygen consumption and central hemodynamics; however, the partial pressure of arterial carbon dioxide was reduced and the partial pressure of arterial oxygen was increased implying that hyperventilation also contributed to the increase in oxygen saturation. The preservation of arterial oxygen saturation and content was particularly evident during hypoxic submaximal exercise, when arterial desaturation typically occurs, but this did not influence arterial-venous oxygen difference.

scholarly journals Molecular Pathways Involved in the Development of Congenital Erythrocytosis

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1150
Author(s):  
Jana Tomc ◽  
Nataša Debeljak
Keyword(s):  
Signal Transduction ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Oxygen Affinity ◽  
Molecular Pathways ◽  
Disease Development ◽  
Post Translational Modifications ◽  
Hemoglobin Oxygen Affinity ◽  
Insight Into ◽  
Idiopathic Erythrocytosis

Patients with idiopathic erythrocytosis are directed to targeted genetic testing including nine genes involved in oxygen sensing pathway in kidneys, erythropoietin signal transduction in pre-erythrocytes and hemoglobin-oxygen affinity regulation in mature erythrocytes. However, in more than 60% of cases the genetic cause remains undiagnosed, suggesting that other genes and mechanisms must be involved in the disease development. This review aims to explore additional molecular mechanisms in recognized erythrocytosis pathways and propose new pathways associated with this rare hematological disorder. For this purpose, a comprehensive review of the literature was performed and different in silico tools were used. We identified genes involved in several mechanisms and molecular pathways, including mRNA transcriptional regulation, post-translational modifications, membrane transport, regulation of signal transduction, glucose metabolism and iron homeostasis, which have the potential to influence the main erythrocytosis-associated pathways. We provide valuable theoretical information for deeper insight into possible mechanisms of disease development. This information can be also helpful to improve the current diagnostic solutions for patients with idiopathic erythrocytosis.

THE ORIGINS OF MUSIC: INNATENESS, UNIQUENESS, AND EVOLUTION

2005 ◽  
Vol 23 (1) ◽  
pp. 29-59 ◽  
Author(s):  
JOSH McDERMOTT ◽  
MARC HAUSER
Keyword(s):  
Side Effects ◽  
Music Perception ◽  
Comparative Psychology ◽  
General Purpose ◽  
Adaptive Significance ◽  
Future Research ◽  
Relative Pitch ◽  
The Past ◽  
Evolution Of Music ◽  
Basic Features

THE ORIGINS and adaptive significance of music, long an elusive target, are now active topics of empirical study, with many interesting developments over the past few years. This article reviews research in anthropology, ethnomusicology, developmental and comparative psychology, neuropsychology, and neurophysiology that bears on questions concerning the origins and evolution of music. We focus on the hypothesis that music perception is constrained by innate, possibly human- and musicspecific principles of organization, as these are candidates for evolutionary explanations. We begin by discussing the distinct roles of different fields of inquiry in constraining claims about innateness and adaptation, and then proceed to review the available evidence. Although research on many of these topics is still in its infancy, at present there is converging evidence that a few basic features of music (relative pitch, the importance of the octave, intervals with simple ratios, tonality, and perhaps elementary musical preferences) are determined in part by innate constraints. At present, it is unclear how many of these constraints are uniquely human and specific to music. Many, however, are unlikely to be adaptations for music, but rather are probably side effects of more general-purpose mechanisms. We conclude by reiterating the significance of identifying processes that are innate, unique to humans, and specific to music, and highlight several possible directions for future research.

scholarly journals CD73 and AMPD3 deficiency enhance metabolic performance via erythrocyte ATP that decreases hemoglobin oxygen affinity

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
William G. O’Brien III ◽  
Vladimir Berka ◽  
Ah-Lim Tsai ◽  
Zhaoyang Zhao ◽  
Cheng Chi Lee
Keyword(s):  
Oxygen Affinity ◽  
Hemoglobin Oxygen Affinity ◽  
Metabolic Performance

120 The Experience of Housing Need Amongst Families Caring for Children with Medical Complexity: A Qualitative Study

2021 ◽  
Vol 26 (Supplement_1) ◽  
pp. e85-e88
Author(s):  
Clara Moore ◽  
Kara Grace Hounsell ◽  
Arielle Zahavi ◽  
Danielle Arje ◽  
Natalie Weiser ◽  
...  
Keyword(s):  
Qualitative Study ◽  
Future Research ◽  
Complex Care ◽  
Housing Situation ◽  
Children With Medical Complexity ◽  
Trade Off ◽  
Housing Preferences ◽  
Medical Needs ◽  
Medical Complexity ◽  
The Impact

Abstract Primary Subject area Complex Care Background Caregivers of children with medical complexity (CMC) face many financial, social and emotional stressors related to their child’s medical condition(s). Previous research has demonstrated that financial stress among this population can have an impact on their housing situation. Families of CMC may face other unique housing challenges such as disability accommodations in the home and housing space and layout. Objectives The primary aim of this study was to explore families’ perspectives and experiences of housing need, and its relationship to their child’s health status as it pertains to CMC. Design/Methods We conducted a qualitative study using semi-structured interviews to identify themes surrounding families of CMC’s experiences of housing need. Parents of CMC were recruited through purposive sampling from the Complex Care Program at a tertiary pediatric health sciences centre. Recruitment ceased when thematic saturation was reached, as determined by consensus of the research team. Interviews were recorded, transcribed verbatim, coded, and analyzed using thematic analysis. Results Twenty parents completed the interview, of whom 89% were mothers and 42% identified a non-English language as their first language. Two major themes and five subthemes (in parentheses) were identified: 1) the impact of health on housing (housing preferences, housing possibilities, housing outcome as a trade-off) and 2) the impact of housing on health (health of the caregiver, health of the child). Some parents reported that their child’s medical needs resulted in specific preferences regarding the location and layout of their home. Parents also indicated that their caregiving role often affected their income and home ownership status, which in turn, affected their housing possibilities. Thus, the housing situation (location and layout of the home) was often the result of a trade-off between the parent’s housing preferences and possibilities. Conclusion Housing is a recognized social determinant of health. We found that among CMC, health also appears to be a significant determinant of housing as families reported that the health of their child impacted their housing preferences and the options available to them (possibilities). To support the health of CMC and their families, policies targeting improved access to subsidized housing, improved sources of funding and regulations allowing families who rent to make accessibility changes are vital. Future research should investigate the impact of household income on housing need and identify interventions to support appropriate housing for CMC.

Features of ozone effect on oxygen-dependent processes in the blood under hypoxic conditions

2021 ◽  
Vol 20 (3) ◽  
pp. 70-76
Author(s):  
V. V. Zinchuk ◽  
E. S. Biletskaya
Keyword(s):  
Malonic Dialdehyde ◽  
Oxygen Affinity ◽  
Diene Conjugates ◽  
Physiological Factor ◽  
Sodium Hydrosulfide ◽  
Hypoxic Conditions ◽  
Hemoglobin Oxygen Affinity ◽  
Gaseous Transmitters ◽  
Dependent Processes

Introduction. Ozone is a physiological factor that can change hemoglobin oxygen affinity and the formation of gaseous transmitters (NO, H2S). The aim is to study the effect of ozone with gaseous transmitters donors on oxygen-dependent processes in the blood under hypoxic conditions in vitro. Materials and methods. Blood samples were divided into 6 groups of 3 ml each. Groups 2, 4, 5, 6 were pretreated with a deoxygenating gas mixture (5.5 % CO2; 94.5 % N2). In groups 3, 4, 5, 6, ozonized isotonic sodium chloride solution (with an ozone concentration of 6 mg/l) was added, and in groups 5 and 6, the donors of gas transmitters nitroglycerin and sodium hydrosulfide, respectively, were additionally introduced. Results. Pre-deoxygenation reduces the effect of ozone on oxygen transport in the blood. Nitroglycerin prevents this effect. The action of ozone under hypoxic conditions leads to an increase of content of NO3-/NO2- and H2S, and combination with nitroglycerin and sodium hydrosulfide increase these parameters. Deoxygenation due to ozone reduces parameters of lipid peroxidation (malonic dialdehyde, diene conjugates), retinol and α-tocopherol, and the same result in the nitroglycerin group. Conclusion. Under hypoxic conditions, a decrease in the effect of ozone on oxygen-dependent processes is reported. Nitroglycerin reduces its manifestation, while sodium hydrosulfide does not have a similar effect.

scholarly journals Long-Term Oxygen Therapy in COPD: evidences and open questions of current indications

2016 ◽  
Vol 73 (1) ◽  
Author(s):  
A. Corrado ◽  
T. Renda ◽  
S. Bertini
Keyword(s):  
Oxygen Therapy ◽  
Supplemental Oxygen ◽  
Future Research ◽  
Chronic Obstructive ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Copd Patients ◽  
Number Of Patients ◽  
Long Term Oxygen Therapy

Long term oxygen therapy (LTOT) has been shown to improve the survival rate in Chronic Obstructive Pulmonary Disease (COPD) patients with severe resting hypoxemia by NOTT and MRC studies, published more than 25 years ago. The improved survival was found in patients who received oxygen for more than 15 hours/day. The effectiveness of LTOT has been documented only in stable COPD patients with severe chronic hypoxemia at rest (PaO255%. In fact no evidence supports the use of LTOT in COPD patients with moderate hypoxemia (55<PaO2<65 mmHg), and in those with decreased oxygen saturation (SO2<90%) during exercise or sleep. Furthermore, it is generally accepted without evidence that LTOT in clinical practice is warranted in other forms of chronic respiratory failure not due to COPD when arterial blood gas criteria match those established for COPD patients. The prescription of oxygen in these circumstances, as for unstable patients, increases the number of patients receiving supplemental oxygen and the related costs. Comorbidities are likely to affect both prognosis and health outcomes in COPD patients, but at the moment we do not know if LTOT in these patients with complex chronic diseases and mild-moderate hypoxemia could be of any use. For these reasons a critical revision of the actual guide lines indications for LTOT in order to optimise effectiveness and costs, and future research in the areas that have not previously been addressed by NOTT and MRC studies, are mandatory.

Sign in / Sign up

Export Citation Format

Share Document