Respiratory physiology of high-altitude anurans: 55 years of research on altitude and oxygen

2007 ◽  
Vol 158 (2-3) ◽  
pp. 307-313 ◽  
Author(s):  
Carlos A. Navas ◽  
José Guilherme Chauí-Berlinck
Keyword(s):  
High Altitude ◽  
Respiratory Physiology

scholarly journals Genetic variation in haemoglobin alters breathing in high-altitude deer mice

2021 ◽  
Author(s):  
Catherine M. Ivy ◽  
Oliver H. Wearing ◽  
Chandrasekhar Natarajan ◽  
Rena M. Schweizer ◽  
Natalia Gutiérrez-Pinto ◽  
...  
Keyword(s):  
Genetic Variation ◽  
High Altitude ◽  
Globin Gene ◽  
Respiratory Physiology ◽  
Deer Mice ◽  
Emergent Properties ◽  
Mixed Genetic Background ◽  
Hypoxia Adaptation ◽  
Globin Gene Expression

ABSTRACTPhysiological systems often have emergent properties but the effects of genetic variation on physiology are often unknown, which presents a major challenge to understanding the mechanisms of phenotypic evolution. We investigated the in vivo effects on respiratory physiology of genetic variants in haemoglobin (Hb) that contribute to hypoxia adaptation in high-altitude deer mice (Peromyscus maniculatus). We created F2 inter-population hybrids of highland and lowland deer mice to test the phenotypic effects of α- and β-globin variants on a mixed genetic background. High-altitude genotypes were associated with breathing phenotypes that enhance O2 uptake in hypoxia, including a deeper more effective breathing pattern and an augmented hypoxic ventilatory response. These effects could not be explained by erythrocyte Hb-O2 affinity or globin gene expression in the brainstem. Therefore, adaptive variation in haemoglobin can have unexpected effects on physiology that are distinct from the canonical function of this protein in circulatory O2 transport.

scholarly journals The alveolar gas equation: do lessons from WW2 research into high flying pilots provide insights into the adaptation to high altitude flight in birds?

2020 ◽  
Author(s):  
Michael Seear
Keyword(s):  
Gas Exchange ◽  
Partial Pressure ◽  
High Altitude ◽  
Oxygen Transport ◽  
Predictive Accuracy ◽  
Gas Diffusion ◽  
Respiratory Physiology ◽  
Partial Pressures ◽  
Starting Point ◽  
Sequential Addition

AbstractDalton’s law of partial pressures applies equally to birds and mammals so, as gas moves from the nostrils to the smallest gas-diffusion airways, the sequential addition of water vapour and CO2, steadily reduce the partial pressure of O2 (PO2) within the gas mixture. The PO2, at the point of gas exchange, at sea level, will be about 60 mm Hg less than the original PO2 within atmospheric air. As a result, the inspired PO2 is an inaccurate starting point for any model of oxygen transport. In humans, the interactions of gases at the point of diffusion, is described and quantified by the Alveolar Gas Equation (AGE). Its development during WW2, provided valuable insights into human gas exchange and also into the responses to high altitude flight in pilots but, except for an early study of hypoxia in pigeons, the AGE is not mentioned in the avian literature. Even detailed models of oxygen transport in birds omit the effect of CO2 clearance on pulmonary oxygen transfer. This paper develops two related arguments concerning the application of the AGE to birds. The first is that avian blood gas predictions, based on the theory of multicapillary serial arterialization (MSA), are inaccurate because they do not account for the added partial pressure of diffused CO2. The second is that the primary adaptation to hypobaric hypoxia is the same for both classes and consists of defending PaO2 by reducing PaCO2 through increasing hyperventilation. Support for the first is demonstrated by comparing PaO2 predictions made using the AGE, with published values from avian studies and also against values predicted by the theory of MSA. The second is illustrated by comparing the results of high altitude studies of both birds and humans. The application of the AGE to avian respiratory physiology would improve the predictive accuracy of models of the O2 cascade and would also provide better insights into the primary adaptation to high altitude flight.

scholarly journals A comparative analysis of lung function and spirometry parameters in genotype-controlled natives living at low and high altitude

2021 ◽  
Author(s):  
Esteban Ortiz-Prado ◽  
Sebastián Encalada ◽  
Johanna Mosquera ◽  
Katherine Simbaña-Rivera ◽  
Lenin Gomez-Barreno ◽  
...  
Keyword(s):  
Lung Function ◽  
High Altitude ◽  
Influencing Factor ◽  
Cross Sectional Study ◽  
Respiratory Physiology ◽  
Categorical Variables ◽  
P Value ◽  
Chi Square ◽  
Cross Sectional ◽  
Restrictive Pattern

Abstract BackgroundThe reference values for lung function are associated to anatomical and lung morphology parameters, but anthropometry it is not the only influencing factor: altitude and genetics are two important agents affecting respiratory physiology. Altitude and its influence on respiratory function has been studied independently of genetics, considering early and long-term acclimatization.ObjectiveThe objective of this study is to evaluate lung function through a spirometry study in autochthonous Kichwas permanently living at low and high-altitude.MethodologyA cross-sectional study of spirometry differences between genetically matched lowland Kichwas from Limoncocha (230 m) at Amazonian basin and high-altitude Kichwas from Oyacachi (3,180 m) in Andean highlands. Chi-square method was used to analyze association or independence of categorical variables, while Student’s t test was applied to comparison of means within quantitative variables. ANOVA, or in the case that the variables didn’t meet the criteria of normality, Kruskal Wallis test were used to compare more than two groups.ResultsPeople from Oyacachi (high altitude) showed a higher predicted values than those from Limonocha (low altitude). The FVC and the FEV1 were significantly greater among highlanders than lowlanders (p value < 0.001). The FEV1/FVC was significantly higher among lowlanders than highlanders for men and women. A restrictive pattern was found in 12.9% of the participants.ConclusionResidents of Oyacachi had greater lung capacity than their peers from Limoncocha, a finding physiologically plausible according to published literature. When analyzing the spirometric patterns obtained in these populations, it was evident that no person had an obstructive pattern, while on the other hand, the restrictive pattern appeared in Limoncocha and Oyacachi populations in 12.9% although it is clear that there is a predominance of this in the individuals belonging to Limoncocha.

scholarly journals Life-long exposure to hypoxia affects metabolism and respiratory physiology across life stages in high-altitude deer mice (Peromyscus maniculatus)

2020 ◽  
Vol 224 (1) ◽  
pp. jeb237024 ◽  
Author(s):  
Catherine M. Ivy ◽  
Graham R. Scott
Keyword(s):  
High Altitude ◽  
Peromyscus Maniculatus ◽  
Adult Life ◽  
Respiratory Physiology ◽  
Deer Mice ◽  
Continuous Exposure ◽  
Life Stages ◽  
Hypoxia Exposure ◽  
In Captivity ◽  
Haemoglobin Content

ABSTRACTHypoxia exposure can have distinct physiological effects between early developmental and adult life stages, but it is unclear how the effects of hypoxia may progress during continuous exposure throughout life. We examined this issue in deer mice (Peromyscus maniculatus) from a population native to high altitude. Mice were bred in captivity in one of three treatment groups: normoxia (controls), life-long hypoxia (∼12 kPa O2 from conception to adulthood) and parental hypoxia (normoxia from conception to adulthood, but parents previously exposed to hypoxia). Metabolic, thermoregulatory and ventilatory responses to progressive stepwise hypoxia and haematology were then measured at post-natal day (P) 14 and 30 and/or in adulthood. Life-long hypoxia had consistent effects across ages on metabolism, attenuating the declines in O2 consumption rate (V̇O2) and body temperature during progressive hypoxia compared with control mice. However, life-long hypoxia had age-specific effects on breathing, blunting the hypoxia-induced increases in air convection requirement (quotient of total ventilation and V̇O2) at P14 and P30 only, but then shifting breathing pattern towards deeper and/or less frequent breaths at P30 and adulthood. Hypoxia exposure also increased blood–O2 affinity at P14 and P30, in association with an increase in arterial O2 saturation in hypoxia at P30. In contrast, parental hypoxia had no effects on metabolism or breathing, but it increased blood–O2 affinity and decreased red cell haemoglobin content at P14 (but not P30). Therefore, hypoxia exposure has some consistent effects across early life and adulthood, and some other effects that are unique to specific life stages.

scholarly journals Ontogenesis of evolved changes in respiratory physiology in deer mice native to high altitude

2020 ◽  
Vol 223 (5) ◽  
pp. jeb219360 ◽  
Author(s):  
Catherine M. Ivy ◽  
Mary A. Greaves ◽  
Elizabeth D. Sangster ◽  
Cayleih E. Robertson ◽  
Chandrasekhar Natarajan ◽  
...  
Keyword(s):  
High Altitude ◽  
Respiratory Physiology ◽  
Deer Mice

scholarly journals Effects of dietary nitrate on respiratory physiology at high altitude - Results from the Xtreme Alps study

Nitric Oxide ◽  
2017 ◽  
Vol 71 ◽  
pp. 57-68 ◽  
Author(s):  
Andrew F. Cumpstey ◽  
Philip J. Hennis ◽  
Edward T. Gilbert-Kawai ◽  
Bernadette O. Fernandez ◽  
Matthieu Poudevigne ◽  
...  
Keyword(s):  
High Altitude ◽  
Respiratory Physiology ◽  
Dietary Nitrate

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

1967 ◽  
Vol 25 ◽  
pp. 366-367
Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
High Altitude ◽  
Amyl Acetate ◽  
Temperature Variations ◽  
Film Forming ◽  
Film Specimen ◽  
Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

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