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Ghosh S, Kiyamu M, Contreras P, León-Velarde F, Bigham A, Brutsaert TD. Exhaled nitric oxide in ethnically diverse high-altitude native populations: A comparative study. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 170:451-458. [PMID: 31396964 DOI: 10.1002/ajpa.23915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/25/2019] [Accepted: 07/18/2019] [Indexed: 11/12/2022]
Abstract
OBJECTIVES Andean and Tibetan high-altitude natives exhibit a high concentration of nitric oxide (NO) in the lungs, suggesting that NO plays an adaptive role in offsetting hypobaric hypoxia. We examined the exhaled NO concentration as well as partial pressure of several additional high-altitude native populations in order to examine the possibility that this putative adaptive trait, that is, high exhaled NO, is universal. METHODS We recruited two geographically diverse highland native populations, Tawang Monpa (TM), a Tibetan derived population in North-Eastern India (n = 95, sampled at an altitude of ~3,200 m), and Peruvian Quechua from the highland Andes (n = 412). The latter included three distinct subgroups defined as those residing at altitude (Q-HAR, n = 110, sampled at 4,338 m), those born and residing at sea-level (Q-BSL, n = 152), and those born at altitude but migrant to sea-level (Q-M, n = 150). In addition, we recruited a referent sample of lowland natives of European ancestry from Syracuse, New York. Fraction of exhaled NO concentrations were measured using a NIOX NIMO following the protocol of the manufacturer. RESULTS Partial pressure of exhaled nitric oxide (PENO) was significantly lower (p < .05) in both high-altitude resident groups (TM = 6.2 ± 0.5 nmHg and Q-HAR = 5.8 ± 0.5 nmHg), as compared to the groups measured at sea level (USA = 14.6 ± 0.7 nmHg, Q-BSL = 18.9 ± 1.6 nmHg, and Q-M = 19.2 ± 1.7 nmHg). PENO was not significantly different between TM and Q-HAR (p < .05). CONCLUSION In contrast to previous work, we found lower PENO in populations at altitude (compared to sea-level) and no difference in PENO between Tibetan and Andean highland native populations. These results do not support the hypothesis that high nitric oxide in human lungs is a universal adaptive mechanism of highland native populations to offset hypobaric hypoxia.
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Affiliation(s)
- Sudipta Ghosh
- Department of Anthropology, North-Eastern Hill University, Shillong, Meghalaya, India
| | - Melisa Kiyamu
- Departamento de Ciencias Biológicas y Fisiológicas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Paloma Contreras
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan
| | - Fabiola León-Velarde
- Departamento de Ciencias Biológicas y Fisiológicas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Abigail Bigham
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan
| | - Tom D Brutsaert
- Department of Exercise Science, Syracuse University, Syracuse, New York
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Álvarez-Herms J, Julià-Sánchez S, Corbi F, Odriozola-Martínez A, Burtscher M. Putative Role of Respiratory Muscle Training to Improve Endurance Performance in Hypoxia: A Review. Front Physiol 2019; 9:1970. [PMID: 30697170 PMCID: PMC6341067 DOI: 10.3389/fphys.2018.01970] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/31/2018] [Indexed: 12/22/2022] Open
Abstract
Respiratory/inspiratory muscle training (RMT/IMT) has been proposed to improve the endurance performance of athletes in normoxia. In recent years, due to the increased use of hypoxic training method among athletes, the RMT applicability has also been tested as a method to minimize adverse effects since hyperventilation may cause respiratory muscle fatigue during prolonged exercise in hypoxia. We performed a review in order to determine factors potentially affecting the change in endurance performance in hypoxia after RMT in healthy subjects. A comprehensive search was done in the electronic databases MEDLINE and Google Scholar including keywords: “RMT/IMT,” and/or “endurance performance,” and/or “altitude” and/or “hypoxia.” Seven appropriate studies were found until April 2018. Analysis of the studies showed that two RMT methods were used in the protocols: respiratory muscle endurance (RME) (isocapnic hyperpnea: commonly 10–30′, 3–5 d/week) in three of the seven studies, and respiratory muscle strength (RMS) (Powerbreathe device: commonly 2 × 30 reps at 50% MIP (maximal inspiratory pressure), 5–7 d/week) in the remaining four studies. The duration of the protocols ranged from 4 to 8 weeks, and it was found in synthesis that during exercise in hypoxia, RMT promoted (1) reduced respiratory muscle fatigue, (2) delayed respiratory muscle metaboreflex activation, (3) better maintenance of SaO2 and blood flow to locomotor muscles. In general, no increases of maximal oxygen uptake (VO2max) were described. Ventilatory function improvements (maximal inspiratory pressure) achieved by using RMT fostered the capacity to adapt to hypoxia and minimized the impact of respiratory stress during the acclimatization stage in comparison with placebo/sham. In conclusion, RMT was found to elicit general positive effects mainly on respiratory efficiency and breathing patterns, lower dyspneic perceptions and improved physical performance in conditions of hypoxia. Thus, this method is recommended to be used as a pre-exposure tool for strengthening respiratory muscles and minimizing the adverse effects caused by hypoxia related hyperventilation. Future studies will assess these effects in elite athletes.
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Affiliation(s)
- Jesús Álvarez-Herms
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Sonia Julià-Sánchez
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Francisco Corbi
- National Institute of Physical Education of Catalonia (INEFC) - Lleida Centre, University of Lleida, Lleida, Spain
| | - Adrian Odriozola-Martínez
- Department of Genetics, Anthropology and Physiology, University of the Basque Country (UPV), Campus de Bizkaia, Bilbao, Spain
| | - Martin Burtscher
- Department of Sport Science, University Innsbruck, Innsbruck, Austria
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Soria R, Egger M, Scherrer U, Bender N, Rimoldi SF. Pulmonary artery pressure and arterial oxygen saturation in people living at high or low altitude: systematic review and meta-analysis. J Appl Physiol (1985) 2016; 121:1151-1159. [PMID: 27660297 DOI: 10.1152/japplphysiol.00394.2016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 09/02/2016] [Accepted: 09/21/2016] [Indexed: 02/08/2023] Open
Abstract
More than 140 million people are living at high altitude worldwide. An increase of pulmonary artery pressure (PAP) is a hallmark of high-altitude exposure and, if pronounced, may be associated with important morbidity and mortality. Surprisingly, there is little information on the usual PAP in high-altitude populations. We, therefore, conducted a systematic review (MEDLINE and EMBASE) and meta-analysis of studies published (in English or Spanish) between 2000 and 2015 on echocardiographic estimations of PAP and measurements of arterial oxygen saturation in apparently healthy participants from general populations of high-altitude dwellers (>2,500 m). For comparison, we similarly analyzed data published on these variables during the same period for populations living at low altitude. Twelve high-altitude studies comprising 834 participants and 18 low-altitude studies (710 participants) fulfilled the inclusion criteria. All but one high-altitude studies were performed between 3,600 and 4,350 m. The combined mean systolic PAP (right ventricular-to-right atrial pressure gradient) at high altitude [25.3 mmHg, 95% confidence interval (CI) 24.0, 26.7], as expected was significantly (P < 0.001) higher than at low altitude (18.4 mmHg, 95% CI 17.1,19.7), and arterial oxygen saturation was significantly lower (90.4%, 95% CI 89.3, 91.5) than at low altitude (98.1%; 95% CI 97.7, 98.4). These findings indicate that at an altitude where the very large majority of high-altitude populations are living, pulmonary hypertension appears to be rare. The reference values and distributions for PAP and arterial oxygen saturation in apparently healthy high-altitude dwellers provided by this meta-analysis will be useful to future studies on the adjustments to high altitude in humans.
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Affiliation(s)
- Rodrigo Soria
- Department of Cardiology and Clinical Research, Inselspital, University of Bern, Switzerland
| | - Matthias Egger
- Institute of Social and Preventive Medicine (ISPM), University of Bern, Switzerland.,Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Urs Scherrer
- Department of Cardiology and Clinical Research, Inselspital, University of Bern, Switzerland.,Facultad de Ciencias, Departamento de Biología, Universidad de Tarapacá, Arica, Chile; and
| | - Nicole Bender
- Institute of Social and Preventive Medicine (ISPM), University of Bern, Switzerland.,Institute of Evolutionary Medicine, University of Zurich, Switzerland
| | - Stefano F Rimoldi
- Department of Cardiology and Clinical Research, Inselspital, University of Bern, Switzerland;
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Niermeyer S, Andrade-M MP, Vargas E, Moore LG. Neonatal oxygenation, pulmonary hypertension, and evolutionary adaptation to high altitude (2013 Grover Conference series). Pulm Circ 2015; 5:48-62. [PMID: 25992270 PMCID: PMC4405714 DOI: 10.1086/679719] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 11/21/2014] [Indexed: 01/30/2023] Open
Abstract
Andeans and Tibetans have less altitude reduction in birth weight than do shorter-resident groups, but only Tibetans are protected from pulmonary hypertension and chronic mountain sickness (CMS). We hypothesized that differences in neonatal oxygenation were involved, with arterial O2 saturation (SaO2) being highest in Tibetans, intermediate in Andeans, and lowest in Han or Europeans, and that improved oxygenation in Andeans relative to Europeans was accompanied by a greater postnatal decline in systolic pulmonary arterial pressures (Ppasys ). We studied 41 healthy (36 Andeans, 5 Europeans) and 9 sick infants at 3,600 m in Bolivia. The SaO2 in healthy babies was highest at 6-24 hours of postnatal age and then declined, whereas sick babies showed the opposite pattern. Compared to that of 30 Tibetan or Han infants studied previously at 3,600 m, SaO2 was higher in Tibetans than in Han or Andeans during wakefulness and active or quiet sleep. Tibetans, as well as Andeans, had higher values than Han while feeding. The SaO2's of healthy Andeans and Europeans were similar and, like those of Tibetans, remained at 85% or above, whereas Han values dipped below 70%. Andean and European Ppasys values were above sea-level norms and higher in sick than in healthy babies, but right heart pressure decreased across 4-6 months in all groups. We concluded that Tibetans had better neonatal oxygenation than Andeans at 3,600 m but that, counter to our hypothesis, neither was SaO2 higher nor Ppa lower in Andean than in European infants. Further, longitudinal studies in these 4 groups are warranted to determine whether neonatal oxygenation influences susceptibility to high-altitude pulmonary hypertension and CMS later in life.
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Affiliation(s)
- Susan Niermeyer
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA
| | - Mario Patricio Andrade-M
- Division of Cardiology (Pediatrics), Caja Nacional de Salud and Clínica del Sur, La Paz, Bolivia
| | - Enrique Vargas
- Department of Respiratory Medicine, Cardiology, and Physiology, Instituto Boliviano de Biología de Altura, La Paz, Bolivia
| | - Lorna G. Moore
- Department of Obstetrics and Gynecology and Center for Women’s Health Research, University of Colorado Denver, Aurora, Colorado, USA
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Ren X, Wang H, Hong H, Qiao H, Man C, Zhao G, Chen L, Li T. Fractional exhaled nitric oxide in healthy Tibetans at high altitude. Med Sci Monit 2014; 20:2565-70. [PMID: 25481354 PMCID: PMC4266363 DOI: 10.12659/msm.891369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Fractional exhaled NO (FENO) is a marker of airway inflammation. For successful use of this marker it is important to have reference ranges from different healthy populations. The aim of this study was to establish these in healthy Tibetan adults who had always lived at high altitude on the Qinghai-Tibet Plateau. Materia/Methods The study included 145 healthy Tibetan subjects, aged 18 to 75 years, who were non-smokers. FENO was measured at a flow rate of 50 mL/s using a chemiluminescence analyzer. Residential altitude was classified as: Grade 1 (3678–3800 m), Grade 2 (3800–4200 m), or Grade 3 (>4200 m). Correlations between subject characteristics (age, sex, height, and weight), altitude, and FENO were investigated. Results The geometric mean FENO (95% CI) was 15.4 (7.0, 35.0) parts per billion (ppb). The 95% upper limit of the log-transformed data was 33.0 ppb, which was slightly lower than that for Han Chinese, and much lower than in the Northwest Han population. Mean FENO values were higher in males (16.8 ppb) than females (14.3 ppb) and inversely related to altitude. Multiple linear regression analysis showed that FENO was predicted by the equation Ln (FENO)=[2.844+0.161 × sex (1 for male; 0 for female) −0.111 × altitude grade]. The residual standard deviation (SD) was 0.048, and the explanatory value was 7%. Conclusions The upper limit of FENO in healthy Tibetan adults is 33 ppb. This value can be predicted on the basis of sex and altitude.
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Affiliation(s)
- Xuewen Ren
- Department of Emergency, Chinese PLA General Hospital, Beijing, China (mainland)
| | - Hao Wang
- Department of Cardiology, Beijing Shijingshan Hospital, Beijing, China (mainland)
| | - Heng Hong
- Department of Geriatric Cardiology, Chinese PLA General Hospital, Beijing, China (mainland)
| | - Huaiyu Qiao
- Department of Cardiology, Jingdezhen 335 Hospital, Jingdezhen, China (mainland)
| | - Chunyan Man
- Department of Emergency, Chinese PLA General Hospital, Beijing, China (mainland)
| | - Gang Zhao
- Department of Cardiology, the Chinese PLA General Hospital, Beijing, China (mainland)
| | - Li Chen
- Department of Emergency, Chinese PLA General Hospital, Beijing, China (mainland)
| | - Tanshi Li
- Department of Emergency, Chinese PLA General Hospital, Beijing, China (mainland)
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6
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Abstract
Populations residing for millennia on the high-altitude plateaus of the world started natural experiments that we can evaluate to address questions about the processes of evolution and adaptation. A 2001 assessment in this journal summarized abundant evidence that Tibetan and Andean high-altitude natives had different phenotypes, and the article made a case for the hypothesis that different genetic bases underlie traits in the two populations. Since then, knowledge of the prehistory of high-altitude populations has grown, information about East African highlanders has become available, genomic science has grown exponentially, and the genetic and molecular bases of oxygen homeostasis have been clarified. Those scientific advances have transformed the study of high-altitude populations. The present review aims to summarize recent advances in understanding with an emphasis on the genetic bases of adaptive phenotypes, particularly hemoglobin concentration among Tibetan highlanders. EGLN1 and EPAS1 encode two crucial proteins contributing to oxygen homeostasis, the oxygen sensor PHD2 and the transcription factor subunit HIF-2α, respectively; they show signals of natural selection such as marked allele frequency differentiation between Tibetans and lowland populations. EPAS1 genotypes associated in several studies with the dampened hemoglobin phenotype that is characteristic of Tibetans at high altitude but did not associate with the dampened response among Amhara from Ethiopia or the vigorous elevation of hemoglobin concentration among Andean highlanders. Future work will likely develop understanding of the integrative biology leading from genotype to phenotype to population in all highland areas.
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Affiliation(s)
- Cynthia M. Beall
- Department of Anthropology, Case Western Reserve University, Cleveland, Ohio 44106–7125
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Colvin KL, Dufva MJ, Delaney RP, Ivy DD, Stenmark KR, Yeager ME. Biomarkers for pediatric pulmonary arterial hypertension - a call to collaborate. Front Pediatr 2014; 2:7. [PMID: 24551834 PMCID: PMC3910125 DOI: 10.3389/fped.2014.00007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/21/2014] [Indexed: 01/07/2023] Open
Abstract
Therapeutic approaches in pediatric pulmonary arterial hypertension (PAH) are based primarily on clinician experience, in contrast to the evidence-based approach in adults with pulmonary hypertension. There is a clear and present need for non-invasive and objective biomarkers to guide the accurate diagnosis, treatment, and prognosis of this disease in children. The multifaceted spectrum of disease, clinical presentation, and association with other diseases makes this a formidable challenge. However, as more progress is being made in the understanding and management of adult PAH, the potential to apply this knowledge to children has never been greater. This review explores the state of the art with regard to non-invasive biomarkers in PAH, with an eye toward those adult PAH biomarkers potentially suitable for application in pediatric PAH.
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Affiliation(s)
- Kelley L Colvin
- Department of Bioengineering, University of Colorado Denver , Aurora, CO , USA ; Department of Pediatrics-Critical Care, University of Colorado Denver , Aurora, CO , USA ; Cardiovascular Pulmonary Research, University of Colorado Denver , Aurora, CO , USA ; Linda Crnic Institute for Down Syndrome, University of Colorado Denver , Aurora, CO , USA
| | - Melanie J Dufva
- Department of Bioengineering, University of Colorado Denver , Aurora, CO , USA ; Department of Pediatrics-Critical Care, University of Colorado Denver , Aurora, CO , USA
| | - Ryan P Delaney
- Department of Bioengineering, University of Colorado Denver , Aurora, CO , USA ; Department of Pediatrics-Critical Care, University of Colorado Denver , Aurora, CO , USA
| | | | - Kurt R Stenmark
- Department of Pediatrics-Critical Care, University of Colorado Denver , Aurora, CO , USA ; Cardiovascular Pulmonary Research, University of Colorado Denver , Aurora, CO , USA
| | - Michael E Yeager
- Department of Bioengineering, University of Colorado Denver , Aurora, CO , USA ; Department of Pediatrics-Critical Care, University of Colorado Denver , Aurora, CO , USA ; Cardiovascular Pulmonary Research, University of Colorado Denver , Aurora, CO , USA ; Linda Crnic Institute for Down Syndrome, University of Colorado Denver , Aurora, CO , USA
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8
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Scherrer U, Allemann Y, Rexhaj E, Rimoldi SF, Sartori C. Mechanisms and Drug Therapy of Pulmonary Hypertension at High Altitude. High Alt Med Biol 2013; 14:126-33. [DOI: 10.1089/ham.2013.1006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Urs Scherrer
- Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
- Facultad de Ciencias, Departamento de Biología, Universidad de Tarapacá, Arica, Chile
| | - Yves Allemann
- Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
| | - Emrush Rexhaj
- Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
| | - Stefano F. Rimoldi
- Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
| | - Claudio Sartori
- Department of Internal Medicine, CHUV, Lausanne, Switzerland
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Allemann Y, Stuber T, de Marchi SF, Rexhaj E, Sartori C, Scherrer U, Rimoldi SF. Pulmonary artery pressure and cardiac function in children and adolescents after rapid ascent to 3,450 m. Am J Physiol Heart Circ Physiol 2012; 302:H2646-53. [PMID: 22523248 DOI: 10.1152/ajpheart.00053.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-altitude destinations are visited by increasing numbers of children and adolescents. High-altitude hypoxia triggers pulmonary hypertension that in turn may have adverse effects on cardiac function and may induce life-threatening high-altitude pulmonary edema (HAPE), but there are limited data in this young population. We, therefore, assessed in 118 nonacclimatized healthy children and adolescents (mean ± SD; age: 11 ± 2 yr) the effects of rapid ascent to high altitude on pulmonary artery pressure and right and left ventricular function by echocardiography. Pulmonary artery pressure was estimated by measuring the systolic right ventricular to right atrial pressure gradient. The echocardiography was performed at low altitude and 40 h after rapid ascent to 3,450 m. Pulmonary artery pressure was more than twofold higher at high than at low altitude (35 ± 11 vs. 16 ± 3 mmHg; P < 0.0001), and there existed a wide variability of pulmonary artery pressure at high altitude with an estimated upper 95% limit of 52 mmHg. Moreover, pulmonary artery pressure and its altitude-induced increase were inversely related to age, resulting in an almost twofold larger increase in the 6- to 9- than in the 14- to 16-yr-old participants (24 ± 12 vs. 13 ± 8 mmHg; P = 0.004). Even in children with the most severe altitude-induced pulmonary hypertension, right ventricular systolic function did not decrease, but increased, and none of the children developed HAPE. HAPE appears to be a rare event in this young population after rapid ascent to this altitude at which major tourist destinations are located.
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Affiliation(s)
- Yves Allemann
- Department of Cardiology, Inselspital, University Hospital, Bern, Switzerland
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Beall CM, Laskowski D, Erzurum SC. Nitric oxide in adaptation to altitude. Free Radic Biol Med 2012; 52:1123-34. [PMID: 22300645 PMCID: PMC3295887 DOI: 10.1016/j.freeradbiomed.2011.12.028] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Revised: 12/29/2011] [Accepted: 12/29/2011] [Indexed: 11/20/2022]
Abstract
This review summarizes published information on the levels of nitric oxide gas (NO) in the lungs and NO-derived liquid-phase molecules in the acclimatization of visitors newly arrived at altitudes of 2500 m or more and adaptation of populations whose ancestors arrived thousands of years ago. Studies of acutely exposed visitors to high altitude focus on the first 24-48 h with just a few extending to days or weeks. Among healthy visitors, NO levels in the lung, plasma, and/or red blood cells fell within 2h, but then returned toward baseline or slightly higher by 48 h and increased above baseline by 5 days. Among visitors ill with high-altitude pulmonary edema at the time of the study or in the past, NO levels were lower than those of their healthy counterparts. As for highland populations, Tibetans had NO levels in the lung, plasma, and red blood cells that were at least double and in some cases orders of magnitude greater than other populations regardless of altitude. Red blood cell-associated nitrogen oxides were more than 200 times higher. Other highland populations had generally higher levels although not to the degree shown by Tibetans. Overall, responses of those acclimatized and those presumed to be adapted are in the same direction, although the Tibetans have much larger responses. Missing are long-term data on lowlanders at altitude showing how similar they become to the Tibetan phenotype. Also missing are data on Tibetans at low altitude to see the extent to which their phenotype is a response to the immediate environment or expressed constitutively. The mechanisms causing the visitors' and the Tibetans' high levels of NO and NO-derived molecules at altitude remain unknown. Limited data suggest processes including hypoxic upregulation of NO synthase gene expression, hemoglobin-NO reactions, and genetic variation. Gains in understanding will require integrating appropriate methods and measurement techniques with indicators of adaptive function under hypoxic stress.
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Affiliation(s)
- Cynthia M Beall
- Case Western Reserve University, Department of Anthropology, 10900 Euclid Avenue, Cleveland, OH 44106, USA, telephone 216 368 2277, telephone during academic year 2011-2012: 216 509 5021, fax 216 368 5334
| | - Daniel Laskowski
- Cleveland Clinic, Department of Pathobiology, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Serpil C. Erzurum
- Cleveland Clinic, Department of Pathobiology, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Brain blood flow in Andean and Himalayan high-altitude populations: evidence of different traits for the same environmental constraint. J Cereb Blood Flow Metab 2011; 31:706-14. [PMID: 20736959 PMCID: PMC3049524 DOI: 10.1038/jcbfm.2010.150] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Humans have populated the Tibetan plateau much longer than the Andean Altiplano. It is thought that the difference in length of occupation of these altitudes has led to different responses to the stress of hypoxia. As such, Andean populations have higher hematocrit levels than Himalayans. In contrast, Himalayans have increased circulation to certain organ systems to meet tissue oxygen demand. In this study, we hypothesize that cerebral blood flow (CBF) is higher in Himalayans than in Andeans. Using a MEDLINE and EMBASE search, we included 10 studies that investigated CBF in Andeans and Himalayans between 3,658 and 4,330 m altitude. The CBF values were corrected for differences in hematocrit and arterial oxygen saturation. The data of these studies show a mean hematocrit of 50% in Himalayans and 54.1% in Andeans. Arterial oxygen saturation was 86.9% in Andeans and 88.4% in Himalayans. The CBF in Himalayans was slightly elevated compared with sea-level subjects, and was 24% higher compared with Andeans. After correction for hematorit and arterial oxygen saturation, CBF was ∼20% higher in Himalayans compared with Andeans. Altered brain metabolism in Andeans, and/or increased nitric oxide availability in Himalayans may have a role to explain this difference in brain blood flow.
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12
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Hoit BD, Dalton ND, Gebremedhin A, Janocha A, Zimmerman PA, Zimmerman AM, Strohl KP, Erzurum SC, Beall CM. Elevated pulmonary artery pressure among Amhara highlanders in Ethiopia. Am J Hum Biol 2010; 23:168-76. [PMID: 21319245 DOI: 10.1002/ajhb.21130] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 09/06/2010] [Accepted: 10/12/2010] [Indexed: 11/07/2022] Open
Abstract
OBJECTIVE Pulmonary arterioles respond to hypoxia with constriction that raises vascular resistance and pulmonary artery blood pressure. The response is sustained indefinitely by the chronic hypoxia of high-altitude residence among highlanders of European and Andean descent, but not Tibetans. The objective of this study was to identify the consequences of lifelong hypoxia exposure for the pulmonary vasculature among Amhara high-altitude natives from Ethiopia. METHODS A three-way static group comparison tested for the effect of Amhara ancestry and high residence altitude on pulmonary hemodynamics measured using echocardiography in samples of 76 healthy adult Amhara lifelong residents at 3700 m, 54 Amhara lifelong residents at 1200 m, and 46 U.S. low-altitude residents at 282 m. RESULTS Amhara at 3700 m had average Doppler-estimated pulmonary artery systolic pressure (tricuspid regurgitant gradient) of 27.9 ± 8.4 (SD) mm Hg as compared with 21.9 ± 4.0 among Amhara at low altitude and 16.5 ± 3.6 in the U.S. low-altitude reference sample. However, there was no residence altitude effect on pulmonary blood flow or vascular resistance. Amhara ancestry was associated with greater pulmonary artery systolic pressure and pulmonary blood flow, yet lower pulmonary vascular resistance. CONCLUSIONS The Amhara at 3700 m had elevated pulmonary artery pressure, but without the elevated pulmonary vascular resistance characteristic of the classic model of the response to long-term hypoxia by the pulmonary vasculature. The elevated pressure among Amhara may be a consequence of high pulmonary blood flow regardless of altitude and represent a newly identified pattern of response.
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Affiliation(s)
- Brian D Hoit
- Department of Medicine, Case Western Reserve University, Cleveland, OH 44106-7125, USA
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13
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Jayet PY, Rimoldi SF, Stuber T, Salmòn CS, Hutter D, Rexhaj E, Thalmann S, Schwab M, Turini P, Sartori-Cucchia C, Nicod P, Villena M, Allemann Y, Scherrer U, Sartori C. Pulmonary and Systemic Vascular Dysfunction in Young Offspring of Mothers With Preeclampsia. Circulation 2010; 122:488-94. [DOI: 10.1161/circulationaha.110.941203] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Adverse events in utero may predispose to cardiovascular disease in adulthood. The underlying mechanisms are unknown. During preeclampsia, vasculotoxic factors are released into the maternal circulation by the diseased placenta. We speculated that these factors pass the placental barrier and leave a defect in the circulation of the offspring that predisposes to a pathological response later in life. The hypoxia associated with high-altitude exposure is expected to facilitate the detection of this problem.
Methods and Results—
We assessed pulmonary artery pressure (by Doppler echocardiography) and flow-mediated dilation of the brachial artery in 48 offspring of women with preeclampsia and 90 offspring of women with normal pregnancies born and permanently living at the same high-altitude location (3600 m). Pulmonary artery pressure was roughly 30% higher (mean±SD, 32.1±5.6 versus 25.3±4.7 mm Hg;
P
<0.001) and flow-mediated dilation was 30% smaller (6.3±1.2% versus 8.3±1.4%;
P
<0.0001) in offspring of mothers with preeclampsia than in control subjects. A strong inverse relationship existed between flow-mediated dilation and pulmonary artery pressure (
r
=−0.61,
P
<0.001). The vascular dysfunction was related to preeclampsia itself because siblings of offspring of mothers with preeclampsia who were born after a normal pregnancy had normal vascular function. Augmented oxidative stress may represent an underlying mechanism because thiobarbituric acid-reactive substances plasma concentration was increased in offspring of mothers with preeclampsia.
Conclusions—
Preeclampsia leaves a persistent defect in the systemic and the pulmonary circulation of the offspring. This defect predisposes to exaggerated hypoxic pulmonary hypertension already during childhood and may contribute to premature cardiovascular disease in the systemic circulation later in life.
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Affiliation(s)
- Pierre-Yves Jayet
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Stefano F. Rimoldi
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Thomas Stuber
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Carlos Salinas Salmòn
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Damian Hutter
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Emrush Rexhaj
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Sébastien Thalmann
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Marcos Schwab
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Pierre Turini
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Céline Sartori-Cucchia
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Pascal Nicod
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Mercedes Villena
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Yves Allemann
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Urs Scherrer
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
| | - Claudio Sartori
- From the Department of Internal Medicine and Botnar Center for Extreme Medicine, University Hospital, Lausanne, Switzerland (P.-Y.J., E.R., S.T., M.S., P.T., C.S.-C., P.N., U.S., C.S.); Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland (S.F.R., T.S., D.H., Y.A.); and Instituto Boliviano de Biologia de Altura, La Paz, Bolivia (C.S.S., M.V.)
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14
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High altitude, a natural research laboratory for the study of cardiovascular physiology and pathophysiology. Prog Cardiovasc Dis 2010; 52:451-5. [PMID: 20417338 DOI: 10.1016/j.pcad.2010.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
High altitude constitutes an exciting natural laboratory for medical research. Although initially, the aim of high-altitude research was to understand the adaption of the organism to hypoxia and find treatments for altitude-related diseases, during the past decade or so, the scope of this research has broadened considerably. Two important observations led the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema represents a unique model that allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Second, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we will review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.
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15
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Abstract
About 30 million people live above 2500 m in the Andean Mountains of South America. Among them are 5.5 million Aymaras, an ethnic group with its own language, living on the altiplano of Bolivia, Peru, and northern Chile at altitudes of up to 4400 m. In this high altitude region traces of human population go back for more than 2000 years with constant evolutionary pressure on its residents for genetic adaptation to high altitude. Aymaras as the assumed direct descendents of the ancient cultures living in this region were the focus of much research interest during the last decades and several distinctive adaptation patterns to life at high altitude have been described in this ethnic group. The aim of this article was to review the physiology and pathophysiology of circulatory adaptation and maladaptation to longtime altitude exposure in Aymaras and Caucasians.
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16
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Hemmingsson T, Linnarsson D. Lower exhaled nitric oxide in hypobaric than in normobaric acute hypoxia. Respir Physiol Neurobiol 2009; 169:74-7. [DOI: 10.1016/j.resp.2009.08.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 08/01/2009] [Accepted: 08/10/2009] [Indexed: 11/29/2022]
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17
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Hemmingsson T, Horn A, Linnarsson D. Measuring exhaled nitric oxide at high altitude. Respir Physiol Neurobiol 2009; 167:292-8. [DOI: 10.1016/j.resp.2009.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 06/03/2009] [Accepted: 06/04/2009] [Indexed: 11/25/2022]
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18
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Schwab M, Jayet PY, Stuber T, Salinas CE, Bloch J, Spielvogel H, Villena M, Allemann Y, Sartori C, Scherrer U. Pulmonary-artery pressure and exhaled nitric oxide in Bolivian and Caucasian high altitude dwellers. High Alt Med Biol 2009; 9:295-9. [PMID: 19115913 DOI: 10.1089/ham.2008.1057] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is evidence that high altitude populations may be better protected from hypoxic pulmonary hypertension than low altitude natives, but the underlying mechanism is incompletely understood. In Tibetans, increased pulmonary respiratory NO synthesis attenuates hypoxic pulmonary hypertension. It has been speculated that this mechanism may represent a generalized high altitude adaptation pattern, but direct evidence for this speculation is lacking. We therefore measured systolic pulmonary-artery pressure (Doppler chocardiography) and exhaled nitric oxide (NO) in 34 healthy, middle-aged Bolivian high altitude natives and in 34 age- and sex-matched, well-acclimatized Caucasian low altitude natives living at high altitude (3600 m). The mean+/-SD systolic right ventricular to right atrial pressure gradient (24.3+/-5.9 vs. 24.7+/-4.9 mmHg) and exhaled NO (19.2+/-7.2 vs. 22.5+/-9.5 ppb) were similar in Bolivians and Caucasians. There was no relationship between pulmonary-artery pressure and respiratory NO in the two groups. These findings provide no evidence that Bolivian high altitude natives are better protected from hypoxic pulmonary hypertension than Caucasian low altitude natives and suggest that attenuation of pulmonary hypertension by increased respiratory NO synthesis may not represent a universal adaptation pattern in highaltitude populations.
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Affiliation(s)
- Marcos Schwab
- Department of Internal Medicine and Botnar Centre for Extreme Medicine, University Hospital, Lausanne, Switzerland
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19
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Severinghaus JW. Sightings. High Alt Med Biol 2008. [DOI: 10.1089/ham.2008.9403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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