Physiological adaptation to high altitude: oxygen transport in mammals and birds

Monge, Carlos; León‐Velarde, Fabiola

doi:10.1152/physrev.1991.71.4.1135

Cited by 331 publications

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“…All subjects were of average fitness; although involved in a different set of studies, their V02max was found to average 43.8 ml O2 kg -1 min -1, assessed by bicycle ergometry and well within the range typical of this subject group (Hochachka et aI., 1991;Matheson et aI., 1991). Initial hematocrit val ues and hemoglobin contents (52.5% ± 3.9 SD and 18.5 ± 1.2 g 100 ml-I, respectively) fell during the 3-week de acclimation period to 46.2% ± 3.4 and 16.5 ± 0.9; both values were somewhat higher than in control subjects (41.8% ± 4.3 and 14.2 ± 1.8), as has been frequently noted in earlier studies (Monge and Leon-Velarde, 1991). Detailed medical history was taken and indicated that the subjects had no known medical problems, no diabetes, and no hypertension.…”

Section: Subjectssupporting

confidence: 80%

“…, 1991;La Manna et aI. , 1992), and the lack of information on effects of hypoxia adaptation of the human brain over lifetime or generational time is even greater (Monge and Leon-Velarde, 1991;Barragan, 1990); with the exception of some ongoing studies by M. Barragan and coworkers (personal communication, Biopathology Conference, Cusco, 1990), studies here are almost nonexistent.…”

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confidence: 89%

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The Brain at High Altitude: Hypometabolism as a Defense against Chronic Hypoxia?

Hochachka

Clark

Brown

et al. 1994

J Cereb Blood Flow Metab

126

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Summary: The brain of hypoxia-tolerant vertebrates is known to survive extreme limitations of oxygen in part because of very low rates of energy production and utili zation. To assess if similar adaptations may be involved in humans during hypoxia adaptation over generational time, volunteer Quechua natives, indigenous to the high Andes between about 3,700 and 4,900 m altitude, served as subjects in positron emission tomographic measure ments of brain regional glucose metabolic rates. Two met abolic states were analyzed: (a) the presumed normal (high altitude-adapted) state monitored as soon as possi ble after leaving the Andes and (b) the de acclimated state monitored after 3 weeks at low altitudes. Proton nuclear magnetic resonance spectroscopy studies of the Quechua brain found normal spectra, with no indication of any unusual lactate accumulation; in contrast, in hypoxia-The central nervous system in humans as in most mammals displays surprisingly high mass-specific metabolic rates and is widely considered to be the most hypoxia sensitive organ in the body. For this reason, and because cerebrovascular disease re mains an unacceptably frequent cause of death in modern societies, a very large research interest fo cuses on mechanisms of defense against O2 limita tion in the mammalian brain. Most studies in this area deal with acute (hypoxia or ischemic) exposure and concentrate (a) on mechanism of damage, and 671tolerant species, a relatively large fraction of the glucose taken up by the brain is released as lactate. Positron emis sion tomographic measurements of [18P]2-deoxy-2-fluoro-o-glucose (PDG) uptake rates, quantified in 26 re gions of the brain, indicated systematically lower region by-region glucose metabolic rates in Quechuas than in lowlanders. The metabolic reductions were least pro nounced in primitive brain structures (e.g., cerebellum) and most pronounced in regions classically associated with higher cortical functions (e.g., frontal cortex). These differences between Quechuas with lifetime exposure to hypobaric hypoxia and lowlanders, which seem to be ex pressed to some degree in most brain regions examined, may be the result of a defense adaptation against chronic hypoxia. Key Words: Brain [18P]deoxyglucose-Brain hypoxia adaptation-Brain glucose metabolism.

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Section: Subjectssupporting

confidence: 80%

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confidence: 89%

The Brain at High Altitude: Hypometabolism as a Defense against Chronic Hypoxia?

Hochachka

Clark

Brown

et al. 1994

J Cereb Blood Flow Metab

126

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“…It should, however, be borne in mind that the molecular adaptations supporting tissue O 2 supply are but part of a symphony of organismic, cellular, and molecular adjustments expressed in high-altitude animals (39,63). As has become well established, hypoxia elicits a fall in (preferred) body temperature, which in anurans, appears to be adenosine and lactate mediated (11,12,67).…”

Section: Discussionmentioning

confidence: 99%

“…In contrast to intensive investigations in birds and mammals (7,39,59), the molecular strategies for O 2 transport in high-altitude ectothermic vertebrates remain unexplored, despite greater variations in environmental conditions (temperature, pH, O 2 tension, etc.) and lesser capacities for homeostatic regulation of internal physical and chemical conditions compared with homeothermic vertebrates and a long-standing interest in high-altitude aquatic amphibians (1,24).…”

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confidence: 99%

Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frogTelmatobius peruvianus

Weber

Ostojic²,

Fago

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

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In contrast to birds and mammals, no information appears to be available on the molecular adaptations for O2 transport in high-altitude ectothermic vertebrates. We investigated Hb of the aquatic Andean frog Telmatobius peruvianus from 3,800-m altitude as regards isoform differentiation, sensitivity to allosteric cofactors, and primary structures of the ␣-and ␤-chains, and we carried out comparative O2-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs show similar functional properties. The high O2 affinity of the major component results from an almost complete obliteration of chloride sensitivity, which correlates with two ␣-chain modifications: blockage of the NH2-terminal residues and replacement by nonpolar Ala of polar residues Ser and Thr found at position ␣131(H14) in human and X. leavis Hbs, respectively. The data indicate adaptive significance of ␣-chain chloride-binding sites in amphibians, in contrast to human Hb where chloride appears mainly to bind in the cavity between the ␤-chains. The findings are discussed in relation to other strategies for high-altitude adaptations in amphibians.amphibians; chloride binding; hypoxia; organic phosphates; oxygen transport HOW IS OXYGEN TRANSPORT to metabolizing tissues secured at high altitude? In contrast to intensive investigations in birds and mammals (7,39,59), the molecular strategies for O 2 transport in high-altitude ectothermic vertebrates remain unexplored, despite greater variations in environmental conditions (temperature, pH, O 2 tension, etc.) and lesser capacities for homeostatic regulation of internal physical and chemical conditions compared with homeothermic vertebrates and a long-standing interest in high-altitude aquatic amphibians (1, 24).The anuran genus Telmatobius (that variously is referred to as frogs or toads) occurs in the Andes mountains at altitudes from 2,000 to over 4,000 m (14) where aerial O 2 tensions fall from ϳ159 mmHg at sea level to ϳ92 mmHg. The hypoxic stress is compounded in aquatic species, particularly at night when photosynthetic activity in the ponds ceases (21). T. culeus found in Lake Titicaca at 3,812 m has reduced, poorly developed lungs but exhibits compensatory physiological and behavioral adaptations (24) that include an "oversized," folded skin, which is penetrated by cutaneous capillaries and ventilated by "bobbing" behavior under hypoxia, and small erythrocytes and higher erythrocyte counts, blood-O 2 affinities, and O 2 -carrying capacities than anurans living at sea level (24). Subspecies of Bufo spinulosus living at sea level and at 3,100 to 4,100 m in the Andes analogously exhibit increasing blood-O 2 affinities with altitude (43).The O 2 affinity of blood is a product of the intrinsic O 2 affinity of the Hb molecules and the erythrocytic effectors that modulate Hb-O 2 affinity. Compared with mammals that use 2,3-diphosphoglycerate (DPG) and fish that use ATP (often in conjunction with the more potent effector guanosine triphosphate) (60) as organic O 2 -affinity modulat...

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“…Highland aquatic vertebrates are constantly challenged by hypoxia, and most of these vertebrates exhibit related functional and structural modifications. Some of these modifications include: heart size, hemoglobin concentration, capillary density, erythrocyte size and changes in respiratory surfaces (Bouverot, 1985;Ruiz et al, 1989;Monge & León-Velarde, 1991;Weber, 1995;Samaja et al, 2003;Nikinmaa, 2013).…”

Section: Introductionmentioning

confidence: 99%

Histological Characteristics of Gills and Dorsal Skin in Ambystoma leorae and Ambystoma rivulare: Morphological Changes for Living at High Altitude

et al. 2017

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ARREDONDO, J.; GONZÁLEZ-MORALES, J. C.; RODRÍGUEZ-ANTOLÍN, J.; BASTIAANS, E.; MONROY-VILCHIS, O.; MANJARREZ, J. & FAJARDO, V.Histological characteristics of gills and dorsal skin in Ambystoma leorae and Ambystoma rivulare: morphological changes for living at high altitude. Int. J. Morphol., 35(4):1590Morphol., 35(4): -1596Morphol., 35(4): , 2017. SUMMARY:Vertebrates exhibit structural changes in their cardiovascular and gas exchange systems in response to hypoxic conditions in high altitude environments. In highland neotenic mole salamanders, as other amphibians, the majority of gases exchange is carried out for skin and gills. But, in high altitude environments, the available oxygen is lower than it is in the air thus, the scarcity of oxygen limits the survival of organisms. Many studies on this subject have focused on understanding the hematological mechanisms that amphibians exhibit in response to hypoxia. However, little is known about possible morphological changes in respiratory structures that may permit increased gas exchange during respiration in high altitude amphibians like Ambystoma leorae and A. rivulare, two threatened Mexican salamander species. The aim of the present study was to describe and compare the histological characteristics of the gills and dorsal skin of A. leorae and A. rivulare from populations at low and high altitudes. We found that, in comparison to lowland organisms, highland ones exhibited more pronounced skin folds, greater numbers of secondary branches in the gills, thinner dorsal and gill epidermises, and greater quantity of melanin surrounding the gill blood vessels. These differences permit a greater capacity for gas exchange and also increase thermoregulatory capacity in high altitude environments.

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Physiological adaptation to high altitude: oxygen transport in mammals and birds

Cited by 331 publications

References 0 publications

The Brain at High Altitude: Hypometabolism as a Defense against Chronic Hypoxia?

The Brain at High Altitude: Hypometabolism as a Defense against Chronic Hypoxia?

Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frogTelmatobius peruvianus

Histological Characteristics of Gills and Dorsal Skin in Ambystoma leorae and Ambystoma rivulare: Morphological Changes for Living at High Altitude

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