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Ding Y, Zhao F, Hu J, Zhao Z, Shi B, Li S. A conjoint analysis of renal structure and omics characteristics reveal new insight to yak high-altitude hypoxia adaptation. Genomics 2024; 116:110857. [PMID: 38729453 DOI: 10.1016/j.ygeno.2024.110857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 04/17/2024] [Accepted: 05/05/2024] [Indexed: 05/12/2024]
Abstract
BACKGROUND Yaks have unique adaptive mechanisms to the hypoxic environment, in which the kidney plays an important role. The aim of this study was to explore the histological changes of yak kidney at different altitudes and the metabolites and genes associated with adaptation to the hypoxic environment. METHODS We analyzed the tissue structure and transcriptomic metabolomic data of yak kidney tissue at two altitudes, 2600 and 4400 m. We compared and identified the morphological adaptations of the kidney and the metabolites and genes associated with hypoxia adaptation in yaks. Changes in renal morphological adaptations, differential metabolites and genes were compared and identified, combining the two in a joint analysis. RESULTS High-altitude yak kidneys showed significant adaptive changes: increased mitochondria, increased glomerular thylakoid area, and decreased localized ribosomes. Transcriptomics and metabolomics identified 69 DAMs (Differential metabolites) and 594 DEGs (differential genes). Functional enrichment analysis showed that the DAMs were associated with protein digestion and absorption, ABC transporter, and MTOR signaling pathway; the DEGs were significantly enriched in Cholesterol metabolism and P53 signaling pathway. The joint analysis indicated that metabolites such as lysine and arginine, as well as key genes such as ABCB5 and COL1A2, were particularly affected under hypoxic conditions, whereas changes in mitochondria in the tissue structure may be related to the expression of MFN1 and OPA1, and changes in glomerular thylakoid membranes are related to VEGFA and TGFB3. CONCLUSION The kidney regulates metabolites and gene expression related to hormone synthesis, protein metabolism, and angiogenesis by adjusting the mitochondrial and glomerular thylakoid membrane structure to support the survival of yaks in high-altitude environments.
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Affiliation(s)
- Yuan Ding
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China
| | - Fangfang Zhao
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
| | - Jiang Hu
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China
| | - Zhidong Zhao
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China
| | - Bingang Shi
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China
| | - Shaobin Li
- Gansu Key Laboratory of Herbivorous Animal Biotechnology, Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
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2
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Barakat RM, Turcani M, Al-Khaledi G, Kilarkaje N, Al-Sarraf H, Sayed Z, Redzic Z. Low oxygen in inspired air causes severe cerebrocortical hypoxia and cell death in the cerebral cortex of awake rats. Neurosci Lett 2024; 818:137515. [PMID: 37865187 DOI: 10.1016/j.neulet.2023.137515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 09/12/2023] [Accepted: 10/09/2023] [Indexed: 10/23/2023]
Abstract
Type 1 respiratory failure (T1RF) is associated with secondary acute brain injury (sABI). The underlying mechanisms of sABI could include injury to brain cells mediated either by hypoxia or by lung injury-triggered inflammation. To elucidate to what extent T1RF causes hypoxia and a consequent hypoxic injury in the brain in the absence of lung injury, we exposed healthy, conscious Sprague-Dawley rats to 48 h long low partial pressure of O2 in inspired air (PiO2) (7.5-8 % O2 in N2, CO2 < 0.5 %, normal barometric pressure) and measured the partial pressure of oxygen in the premotor cortex (PtO2), cerebral blood flow (CBF), lactate concentrations, and cell death. Low PiO2 significantly affected PtO2, which was 52.3 (SD 2.1) mmHg when PiO2 was normal but declined to 6.4 (SD 3.8) mmHg when PiO2 was low for 1 h. This was accompanied by increased lactate concentrations in plasma, CSF, and premotor cortex. Low PiO2 elevated the number of dead cells in the cerebral cortex from 5.6 (SD 4.8) % (when PiO2 was normal) to 20.5 (SD 4.1) % and 32.37 (SD 6.5) % after 24 h and 48 h exposure to low PiO2, respectively. The Mann-Kendall test could not detect any monotonic increase or decrease in pial blood flow during the 48 h exposure to low PiO2. In summary, our findings suggest that exposure to low PiO2 caused a severe hypoxia in the cerebral cortex, which triggers a massive cell death. Since these conditions mimic T1RF, hypoxic injury could be an important underlying cause of T1RF-induced sABI.
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Affiliation(s)
- Rawan M Barakat
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Marian Turcani
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Ghanim Al-Khaledi
- Department of Pharmacology, College of Medicine, Kuwait University, Kuwait
| | | | - Hameed Al-Sarraf
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zeinab Sayed
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zoran Redzic
- Department of Physiology, College of Medicine, Kuwait University, Kuwait.
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3
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Li S, Mu D, Ma C, Yixicuomu, Zhaxiyangzong, Pang J, Zhan M, Liu Z, Dan Q, Cheng X. Establishment of a reference interval for total carbon dioxide using indirect methods in Chinese populations living in high-altitude areas: A retrospective real-world analysis. Clin Biochem 2023; 119:110631. [PMID: 37572984 DOI: 10.1016/j.clinbiochem.2023.110631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/03/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
BACKGROUND Hypoxia leads to different concentrations of the bicarbonate buffer system in Tibetan people. Indirect methods were used to establish the reference interval (RI) for total carbon dioxide (tCO2) based on big data from the adult population of Tibet, a high-altitude area in Western China. METHODS Anonymous tCO2 test data (n = 442,714) were collected from the People's Hospital of the Tibet Autonomous Region from January 2018, to December 2021. Multiple linear regression and variance component analyses were performed to assess the effects of sex, age, and race on tCO2 levels. Indirect methods, including Hoffmann, Bhattacharya, expectation maximization (EM), kosmic and refineR, were used to calculate the total RI and ethnicity-partitioned RI. RESULTS A total of 230,821 real-world tCO2 test results were eligible. Sex, age, and race were significantly associated with the tCO2 levels. The total and ethnically-partitioned RIs estimated using the five indirect methods were comparable. The total RI of tCO2 was 14-24 mmol/L (calculated using Hoffmann and refineR) and 15-24 mmol/L (Bhattacharya, EM and kosmic). For Han nationality, the RIs were 14-25 mmol/L (calculated using Hoffmann and Bhattacharya), 16-23 mmol/L (EM), 15-24 mmol/L (kosmic), and 14.2-24.5 mmol/L (refineR). For the Tibetan population, the RIs were 14-24 mmol/L (calculated using Hoffmann and refineR), 15-24 mmol/L (Bhattacharya and kosmic), and 15-23 mmol/L (EM). The established RIs were significantly lower than those living at lower altitudes area (22-29 mmol/L) that was provided by the manufacturer. CONCLUSION The tCO2 RI of the populations living on the Tibetan Plateau was significantly lower than those at the lower altitudes. The RIs established using indirect methods are suitable for clinical applications in Tibet.
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Affiliation(s)
- Shensong Li
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China
| | - Danni Mu
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing, China
| | - Chaochao Ma
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing, China
| | - Yixicuomu
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China
| | - Zhaxiyangzong
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China
| | - Jinrong Pang
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China
| | - Mingjun Zhan
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China
| | - Zhijuan Liu
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China.
| | - Qu Dan
- Department of Clinical Laboratory, People's Hospital of Tibet Autonomous Region, Lhasa, China.
| | - Xinqi Cheng
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing, China.
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4
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Midha AD, Zhou Y, Queliconi BB, Barrios AM, Haribowo AG, Chew BTL, Fong COY, Blecha JE, VanBrocklin H, Seo Y, Jain IH. Organ-specific fuel rewiring in acute and chronic hypoxia redistributes glucose and fatty acid metabolism. Cell Metab 2023; 35:504-516.e5. [PMID: 36889284 PMCID: PMC10077660 DOI: 10.1016/j.cmet.2023.02.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/20/2022] [Accepted: 02/08/2023] [Indexed: 03/09/2023]
Abstract
Oxygen deprivation can be detrimental. However, chronic hypoxia is also associated with decreased incidence of metabolic syndrome and cardiovascular disease in high-altitude populations. Previously, hypoxic fuel rewiring has primarily been studied in immortalized cells. Here, we describe how systemic hypoxia rewires fuel metabolism to optimize whole-body adaptation. Acclimatization to hypoxia coincided with dramatically lower blood glucose and adiposity. Using in vivo fuel uptake and flux measurements, we found that organs partitioned fuels differently during hypoxia adaption. Acutely, most organs increased glucose uptake and suppressed aerobic glucose oxidation, consistent with previous in vitro investigations. In contrast, brown adipose tissue and skeletal muscle became "glucose savers," suppressing glucose uptake by 3-5-fold. Interestingly, chronic hypoxia produced distinct patterns: the heart relied increasingly on glucose oxidation, and unexpectedly, the brain, kidney, and liver increased fatty acid uptake and oxidation. Hypoxia-induced metabolic plasticity carries therapeutic implications for chronic metabolic diseases and acute hypoxic injuries.
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Affiliation(s)
- Ayush D Midha
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Medical Scientist Training Program, University of California, San Francisco, San Francisco, CA 94143, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuyin Zhou
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Bruno B Queliconi
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Alec M Barrios
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Augustinus G Haribowo
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Brandon T L Chew
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Pharmaceutical Sciences and Pharmacogenomics Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Cyril O Y Fong
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
| | - Joseph E Blecha
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
| | - Henry VanBrocklin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
| | - Youngho Seo
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
| | - Isha H Jain
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
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5
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Mallet RT, Burtscher J, Pialoux V, Pasha Q, Ahmad Y, Millet GP, Burtscher M. Molecular Mechanisms of High-Altitude Acclimatization. Int J Mol Sci 2023; 24:ijms24021698. [PMID: 36675214 PMCID: PMC9866500 DOI: 10.3390/ijms24021698] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/17/2023] Open
Abstract
High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.
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Affiliation(s)
- Robert T. Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Vincent Pialoux
- Inter-University Laboratory of Human Movement Biology EA7424, University Claude Bernard Lyon 1, University of Lyon, FR-69008 Lyon, France
| | - Qadar Pasha
- Institute of Hypoxia Research, New Delhi 110067, India
| | - Yasmin Ahmad
- Defense Institute of Physiology & Allied Sciences (DIPAS), Defense Research & Development Organization(DRDO), New Delhi 110054, India
| | - Grégoire P. Millet
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, A-6020 Innsbruck, Austria
- Austrian Society for Alpine and High-Altitude Medicine, A-6020 Innsbruck, Austria
- Correspondence:
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6
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Liu F, Sui X, Wang Q, Li J, Yang W, Yang Y, Xiao Z, Sun Y, Guo X, Yang X, Yang J, Wang Y, Luo Y. Insights into the pharmacodynamics and pharmacokinetics of meldonium after exposure to acute high altitude. Front Pharmacol 2023; 14:1119046. [PMID: 36909160 PMCID: PMC9992410 DOI: 10.3389/fphar.2023.1119046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/13/2023] [Indexed: 02/25/2023] Open
Abstract
Objective: Meldonium, a well-known cardioprotective drug, has been reported to be protective against pulmonary injury at high altitudes; however, the pharmacodynamics of meldonium in other vital organs under acute high-altitude injury are less investigated and the related pharmacokinetics have not been fully elucidated. Methods and Results: The present study examined the basic pharmacodynamics and pharmacokinetics (PK) in rat exposure to acute high-altitude hypoxia after intragastrical and intravenous pre-administration of meldonium. The results indicate that meldonium can improve acute hypoxia-induced pathological damage in brain and lung tissues, and restore blood biochemistry and routine blood index of heart, liver and kidney tissues under a simulated acute high-altitude environment. Furthermore, compared to the normoxia group, rats exposed to simulated high-altitude hypoxia and premedicated with intragastrical meldonium showed linear kinetics in the dose range of 25-100 mg/kg, with a significantly increase in the area under curve (AUC) and reduced clearance rate. No significant differences in these meldonium of PK parameters were observed with intravenous administration. Additionally, meldonium was involved in the regulation of succinic acid and 3-hydroxypropionic acid. Conclusion: These results will contribute to our understanding of the preclinical PK properties of meldonium and its acute high-altitude protective effects.
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Affiliation(s)
- Fengying Liu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Xin Sui
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Qian Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Jinglai Li
- Guollence Pharmaceutical Technology Co., Ltd., Beijing, China
| | - Weijie Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yi Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Zhenyu Xiao
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yangyang Sun
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Xiaoxuan Guo
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China.,School of Pharmaceutical Science, Liaoning University, Shenyang, China
| | - Xinyi Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Jun Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yuan Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
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7
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Cates VC, Bruce CD, Marullo AL, Isakovich R, Saran G, Leacy JK, O′Halloran KD, Brutsaert TD, Sherpa MT, Day TA. Steady-state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide. Physiol Rep 2022; 10:e15521. [PMID: 36461658 PMCID: PMC9718940 DOI: 10.14814/phy2.15521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023] Open
Abstract
Ventilatory acclimatization (VA) is important to maintain adequate oxygenation with ascent to high altitude (HA). Transient hypoxic ventilatory response tests lack feasibility and fail to capture the integrated steady-state responses to chronic hypoxic exposure in HA fieldwork. We recently characterized a novel index of steady-state respiratory chemoreflex drive (SSCD), accounting for integrated contributions from central and peripheral respiratory chemoreceptors during steady-state breathing at prevailing chemostimuli. Acetazolamide is often utilized during ascent for prevention or treatment of altitude-related illnesses, eliciting metabolic acidosis and stimulating respiratory chemoreceptors. To determine if SSCD reflects VA during ascent to HA, we characterized SSCD in 25 lowlanders during incremental ascent to 4240 m over 7 days. We subsequently compared two separate subgroups: no acetazolamide (NAz; n = 14) and those taking an oral prophylactic dose of acetazolamide (Az; 125 mg BID; n = 11). At 1130/1400 m (day zero) and 4240 m (day seven), steady-state measurements of resting ventilation (V̇I ; L/min), pressure of end-tidal (PET )CO2 (Torr), and peripheral oxygen saturation (SpO2 ; %) were measured. A stimulus index (SI; PET CO2 /SpO2 ) was calculated, and SSCD was calculated by indexing V̇I against SI. We found that (a) both V̇I and SSCD increased with ascent to 4240 m (day seven; V̇I : +39%, p < 0.0001, Hedges' g = 1.52; SSCD: +56.%, p < 0.0001, Hedges' g = 1.65), (b) and these responses were larger in the Az versus NAz subgroup (V̇I : p = 0.02, Hedges' g = 1.04; SSCD: p = 0.02, Hedges' g = 1.05). The SSCD metric may have utility in assessing VA during prolonged stays at altitude, providing a feasible alternative to transient chemoreflex tests.
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Affiliation(s)
- Valerie C. Cates
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Christina D. Bruce
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Anthony L. Marullo
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | - Rodion Isakovich
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Gurkarn Saran
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Jack K. Leacy
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | - Ken D. O′Halloran
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | | | | | - Trevor A. Day
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
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8
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Burtscher J, Mallet RT, Pialoux V, Millet GP, Burtscher M. Adaptive Responses to Hypoxia and/or Hyperoxia in Humans. Antioxid Redox Signal 2022; 37:887-912. [PMID: 35102747 DOI: 10.1089/ars.2021.0280] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Significance: Oxygen is indispensable for aerobic life, but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue, and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. Recent Advances: Hyperbaric oxygen therapy is already a cornerstone of modern medicine, and the application of mild hypoxia, that is, hypoxia conditioning (HC), to strengthen the resilience of organs or the whole body to severe hypoxic insults is an important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. HC-sometimes in combination with hyperoxic interventions-is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement. Critical Issues: The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks versus benefits are as yet ill-defined. Future Directions: The field of low and high oxygen conditioning is expanding rapidly, and novel applications are increasingly recognized, for example, the modulation of aging processes, mood disorders, or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration, and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount. Antioxid. Redox Signal. 37, 887-912.
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Affiliation(s)
- Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Vincent Pialoux
- Inter-University Laboratory of Human Movement Biology EA7424, University Claude Bernard Lyon 1, University of Lyon, Lyon, France
| | - Grégoire P Millet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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9
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Wang SY, Gao J, Zhao JH. Effects of high altitude on renal physiology and kidney diseases. Front Physiol 2022; 13:969456. [PMID: 36338473 PMCID: PMC9630589 DOI: 10.3389/fphys.2022.969456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
The hypobaric and hypoxic conditions of high-altitude areas exert adverse effects on the respiratory, circulatory and nervous systems. The kidneys have an abundant blood supply (20%–25% of cardiac output) and high blood flow; thus, they are susceptible to the effects of hypoxia. However, the effects of acute and chronic exposure to high altitudes on renal physiology and pathology are not fully understood. Moreover, few studies have investigated the impact of high-altitude exposure on patients with chronic kidney disease or acute kidney injury. In this review, we summarized changes in renal physiology and renal pathology due to high-altitude exposure as well as the impact of high-altitude exposure on existing kidney diseases, with the aim of informing the prevention and treatment of kidney diseases at high altitudes.
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Affiliation(s)
- Si-Yang Wang
- 953th Hospital, Shigatse Branch, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jie Gao
- Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Jing-Hong Zhao
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Chongqing Clinical Research Center of Kidney and Urology Diseases, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
- *Correspondence: Jing-Hong Zhao,
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10
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Yang S, Tian C, Yang F, Chen Q, Geng R, Liu C, Wu X, Lam WK. Cardiorespiratory function, resting metabolic rate and heart rate variability in coal miners exposed to hypobaric hypoxia in highland workplace. PeerJ 2022; 10:e13899. [PMID: 36061757 PMCID: PMC9438770 DOI: 10.7717/peerj.13899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/23/2022] [Indexed: 01/19/2023] Open
Abstract
Background Owing to intermittent/acute exposure to hypobaric hypoxia, highland miners may often suffer, the physiological characteristics between highland and lowland miners, however, are rarely reported. The objective of this study was to compare the physiological characteristics of coal miners working at disparate altitudes. Methods Twenty-three male coal mining workers acclimating to high altitude for 30 ± 6 days in Tibet (highland group; approx. 4500 m above sea level; 628.39 millibar), and 22 male coal mining workers in Hebei (lowland group; less than 100 m above sea level; 1021.82 millibar) were recruited. Tests were conducted to compare ventilatory parameters, circulation parameters, resting metabolic rate (RMR), and heart rate variability (HRV) indices between the two groups in resting state. Results Ventilation volume per minute (VE) of the highland group was markedly raised compared to that of the lowland group (11.70 ± 1.57 vs. 8.94 ± 1.97 L/min, p = 0.000). In the meanwhile, O2 intake per heart beat (VO2/HR) was strikingly decreased (3.54 ± 0.54 vs. 4.36 ± 0.69 ml/beat, p = 0.000). Resting metabolic rate relevant to body surface area (RMR/BSA) was found no significant difference between the two groups. Evident reduction in standard deviation of NN intervals (SDNN) and remarkable increase in ratio of low- and high- frequency bands (LF/HF) were manifest in highland miners compared to that of lowland ones (110.82 ± 33.34 vs. 141.44 ± 40.38, p = 0.008 and 858.86 ± 699.24 vs. 371.33 ± 171.46, p = 0.003; respectively). Conclusions These results implicate that long-term intermittent exposure to high altitude can lead miners to an intensified respiration, a compromised circulation and a profound sympathetic-parasympathetic imbalance, whereas the RMR in highland miners does not distinctly decline.
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Affiliation(s)
- Sanjun Yang
- Department of Physical Education, China University of Mining and Technology-Beijing, Beijing, China
| | - Chunhu Tian
- Department of Physical Education, China University of Mining and Technology-Beijing, Beijing, China
| | - Fan Yang
- Sports Science Research Center, Li Ning Center, Beijing, China
| | - Qi Chen
- The University of International Business and Economics, Beijing, China
| | - Ruiyuan Geng
- Department of Physical Education, China University of Mining and Technology-Beijing, Beijing, China
| | - Chunyan Liu
- The Third Affiliated Hospital of Beijing University of Chinese Medicine, Beijing, China
| | - Xinrong Wu
- School of Emergency Management and Safety Engineering, China University of Mining and Technology-Beijing, Beijing, China
| | - Wing-Kai Lam
- Sports Information and External Affairs Centre, Hong Kong Sports Institute, Sha Tin, Hong Kong, China
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11
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Milloy KM, White MG, Chicilo JOC, Cummings KJ, Pfoh JR, Day TA. Assessing central and peripheral respiratory chemoreceptor interaction in humans. Exp Physiol 2022; 107:1081-1093. [PMID: 35766127 DOI: 10.1113/ep089983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 06/16/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? We investigated the interaction between central and peripheral respiratory chemoreceptors in healthy, awake human participants by (a) using a background of step increases in steady-state normoxic fraction of inspired carbon dioxide to alter central chemoreceptor activation and (b) using the transient hypoxia test to target the peripheral chemoreceptors. What is the main finding and its importance? Our data suggests that the central-peripheral respiratory chemoreceptor interaction is additive in minute ventilation and respiratory rate, but hypoadditive in tidal volume. Our study adds important new data in reconciling chemoreceptor interaction in awake healthy humans, and is consistent with previous reports of simple addition in intact rodents and humans. ABSTRACT Arterial blood gas levels are maintained through respiratory chemoreflexes, mediated by central (CCR) in the CNS and peripheral (PCR) chemoreceptors located in the carotid bodies. The interaction between central and peripheral chemoreceptors is controversial, and few studies have investigated this interaction in awake healthy humans, in part due to methodological challenges. We investigated the interaction between the CCRs and PCRs in healthy humans using a transient hypoxia test (three consecutive breaths of 100% N2 ; TT-HVR), which targets the stimulus and temporal domain specificity of the PCRs. TT-HVRs were superimposed upon three randomized background levels of steady-state inspired fraction of normoxic CO2 (FI CO2 ; 0, 0.02 and 0.04). Chemostimuli (calculated oxygen saturation; ScO2 ) and respiratory variable responses (respiratory rate, inspired tidal volume and ventilation; RR , VTI , V̇I ), were averaged from all three TT-HVR trials at each FI CO2 level. Responses were assessed as (a) a change from BL (delta; ∆) and (b) indexed against ∆ScO2 . Aside from a significantly lower ∆VTI response in 0.04 FI CO2 (P = 0.01), the hypoxic rate responses (∆RR or ∆RR /∆ScO2 ; P = 0.46, P = 0.81), hypoxic tidal volume response (∆VTI /∆ScO2 ; P = 0.08) and the hypoxic ventilatory responses (∆V̇I and (∆V̇I /∆ScO2 ; P = 0.09 and P = 0.31) were not significantly different across FI CO2 trials. Our data suggests simple addition between central and peripheral chemoreceptors in V̇I , which is mediated through simple addition in RR responses, but hypo-addition in VTI responses. Our study adds important new data in reconciling chemoreceptor interaction in awake healthy humans, and is consistent with previous reports of simple addition in intact rodents and humans. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kristin M Milloy
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Matthew G White
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Janelle O C Chicilo
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | | | - Jamie R Pfoh
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
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12
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Steele AR, Ainslie PN, Stone R, Tymko K, Tymko C, Howe CA, MacLeod D, Anholm JD, Gasho C, Tymko MM. Global REACH 2018: Characterizing Acid-Base Balance Over 21 Days at 4,300 m in Lowlanders. High Alt Med Biol 2022; 23:185-191. [PMID: 35231184 DOI: 10.1089/ham.2021.0115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Steele, Andrew R., Philip N. Ainslie, Rachel Stone, Kaitlyn Tymko, Courtney Tymko, Connor A. Howe, David MacLeod, James D. Anholm, Christopher Gasho, and Michael M. Tymko. Global REACH 2018: characterizing acid-base balance over 21 days at 4,300 m in lowlanders. High Alt Med Biol. 23:185-191, 2022. Introduction: High altitude exposure results in hyperventilatory-induced respiratory alkalosis, followed by metabolic compensation to return arterial blood pH (pHa) toward sea level values. However, previous work has limited sample sizes, short-term exposure, and pharmacological confounders (e.g., acetazolamide). The purpose of this investigation was to characterize acid-base balance after rapid ascent to high altitude (i.e., 4,300 m) in lowlanders. We hypothesized that despite rapid bicarbonate ([HCO3-]) excretion during early acclimatization, partial respiratory alkalosis would still be apparent as reflected in elevations in pHa compared with sea level after 21 days of acclimatization to 4,300 m. Methods: In 16 (3 female) healthy volunteers not taking any medications, radial artery blood samples were collected and analyzed at sea level (150 m; Lima, Peru), and on days 1, 3, 7, 14, and 21 after rapid automobile (∼8 hours) ascent to high altitude (4,300 m; Cerro de Pasco, Peru). Results and Discussion: Although reductions in [HCO3-] occurred by day 3 (p < 0.01), they remained stable thereafter and were insufficient to fully normalize pHa back to sea level values over the subsequent 21 days (p < 0.01). These data indicate that only partial compensation for respiratory alkalosis persists throughout 21 days at 4,300 m.
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Affiliation(s)
- Andrew R Steele
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Rachel Stone
- Department of Kinesiology, University of Windsor, Windsor, Ontario, Canada
| | - Kaitlyn Tymko
- Department of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Courtney Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - David MacLeod
- Human Pharmacology and Physiology Lab, Duke University Medical Center, Durham, North Carolina, USA
| | - James D Anholm
- Division of Pulmonary and Critical Care, Department of Medicine, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Christopher Gasho
- Division of Pulmonary and Critical Care, Department of Medicine, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada.,Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
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13
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Chen P, Liu Y, Liu W, Wang Y, Liu Z, Rong M. Impact of High-Altitude Hypoxia on Bone Defect Repair: A Review of Molecular Mechanisms and Therapeutic Implications. Front Med (Lausanne) 2022; 9:842800. [PMID: 35620712 PMCID: PMC9127390 DOI: 10.3389/fmed.2022.842800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/15/2022] [Indexed: 11/23/2022] Open
Abstract
Reaching areas at altitudes over 2,500–3,000 m above sea level has become increasingly common due to commerce, military deployment, tourism, and entertainment. The high-altitude environment exerts systemic effects on humans that represent a series of compensatory reactions and affects the activity of bone cells. Cellular structures closely related to oxygen-sensing produce corresponding functional changes, resulting in decreased tissue vascularization, declined repair ability of bone defects, and longer healing time. This review focuses on the impact of high-altitude hypoxia on bone defect repair and discusses the possible mechanisms related to ion channels, reactive oxygen species production, mitochondrial function, autophagy, and epigenetics. Based on the key pathogenic mechanisms, potential therapeutic strategies have also been suggested. This review contributes novel insights into the mechanisms of abnormal bone defect repair in hypoxic environments, along with therapeutic applications. We aim to provide a foundation for future targeted, personalized, and precise bone regeneration therapies according to the adaptation of patients to high altitudes.
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Affiliation(s)
- Pei Chen
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Yushan Liu
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Wenjing Liu
- Department of Prosthodontics, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Yarong Wang
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Ziyi Liu
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Mingdeng Rong
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
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14
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Tymko MM, Willie CK, Howe CA, Hoiland RL, Stone R, Tymko K, Tymko C, MacLeod DB, Anholm J, Gasho C, Villafuerte FC, Vizcardo Galindo GA, Figueroa-Mujíca RJ, Day TA, Bird JD, Foster GE, Steinback CD, Brugniaux J, Champigneulle B, Stauffer E, Doutreleau S, Verges S, Swenson ER, Ainslie PN. Acid-base balance at high altitude in lowlanders and indigenous highlanders. J Appl Physiol (1985) 2022; 132:575-580. [PMID: 35023761 DOI: 10.1152/japplphysiol.00757.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH(a) toward sea-level values. However, acid-base balance has not been comprehensively examined in both lowlanders and indigenous populations - where the latter are thought to be fully adapted to high-altitude. The purpose of this investigation was to compare acid-base balance between acclimatizing lowlanders, and Andean and Sherpa highlanders at various altitudes (~3,800, ~4,300, and ~5,000 m). We compiled data collected across five independent high-altitude expeditions and report the following novel findings: 1) at 3,800 m, Andeans (n=7) had elevated pHa compared to Sherpas (n=12; P<0.01), but not to lowlanders (n=16; nine days acclimatized; P=0.09); 2) at 4,300 m, lowlanders (n=16; 21 days acclimatized) had elevated pHa compared to Andeans (n=32) and Sherpas (n=11; both P<0.01), and Andeans had elevated pHa compared to Sherpas (P=0.01); and 3) at 5,000 m, lowlanders (n=16; 14 days acclimatized) had higher pHa compared to both Andeans (n=66) and Sherpas (n=18; P<0.01, and P=0.03, respectively), and Andean and Sherpa highlanders had similar blood pHa (P=0.65). These novel data characterize acid-base balance acclimatization and adaptation to various altitudes in lowlanders and indigenous highlanders.
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Affiliation(s)
- Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada.,Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Christopher K Willie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada.,Department of Anaesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada
| | | | | | - Courtney Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Duke University Medical Center, Durham, NC, United States
| | - James Anholm
- Department of Medicine, Division of Pulmonary and Critical Care, Loma Linda University School of Medicine, Loma, CA, United States
| | - Christopher Gasho
- Department of Medicine, Division of Pulmonary and Critical Care, Loma Linda University School of Medicine, Loma, CA, United States
| | | | - Gustavo A Vizcardo Galindo
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada.,Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen Edward Foster
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
| | - Craig D Steinback
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Julien Brugniaux
- HP2 laboratory, Univ. Grenoble Alpes, INSERM, CHU Grenoble Alpes, Grenoble, France
| | - Benoit Champigneulle
- HP2 laboratory, Univ. Grenoble Alpes, INSERM, CHU Grenoble Alpes, Grenoble, France
| | - Emeric Stauffer
- Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424,Université Claude Bernard Lyon 1, France
| | - Stephane Doutreleau
- HP2 laboratory, Univ. Grenoble Alpes, INSERM, CHU Grenoble Alpes, Grenoble, France
| | - Samuel Verges
- HP2 laboratory, Univ. Grenoble Alpes, INSERM, CHU Grenoble Alpes, Grenoble, France
| | - Erik R Swenson
- UPulmonary and Critical Care Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
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15
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Bird JD, Kalker A, Rimke AN, Chan JS, Chan G, Saran G, Jendzjowsky NG, Wilson RJA, Brutsaert TD, Sherpa MT, Day TA. Severity of central sleep apnea does not affect sleeping oxygen saturation during ascent to high altitude. J Appl Physiol (1985) 2021; 131:1432-1443. [PMID: 34435507 DOI: 10.1152/japplphysiol.00363.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Central sleep apnea (CSA) is characterized by periodic breathing (PB) during sleep, defined as intermittent periods of apnea/hypopnea and hyperventilation, with associated acute fluctuations in oxyhemoglobin saturation (SO2). CSA has an incidence of ∼50% in heart failure patients but is universal at high altitude (HA; ≥2,500 m), increasing in severity with further ascent and/or time at altitude. However, whether PB is adaptive, maladaptive, or neutral with respect to sleeping SO2 at altitude is unclear. We hypothesized that PB severity would improve mean sleeping SO2 during acclimatization to HA due to relative, intermittent hyperventilation subsequent to each apnea. We utilized portable sleep monitors to assess the incidence and severity of CSA via apnea-hypopnea index (AHI) and oxygen desaturation index (ODI), and peripheral oxygen saturation ([Formula: see text]) during sleep during two ascent profiles to HA in native lowlanders: 1) rapid ascent to and residence at 3,800 m for 9 days/nights (n = 21) and 2) incremental ascent to 5,160 m over 10 days/nights (n = 21). In both ascent models, severity of AHI and ODI increased and mean sleeping [Formula: see text] decreased, as expected. However, during sleep on the last night/highest altitude of both ascent profiles, neither AHI nor ODI were correlated with mean sleeping [Formula: see text]. In addition, mean sleeping [Formula: see text] was not significantly different between high and low CSA. These data suggest that CSA is neither adaptive nor maladaptive with regard to mean oxygen saturation during sleep, owing to the relative hyperventilation between apneas, likely correcting transient apnea-mediated oxygen desaturation and maintaining mean oxygenation.NEW & NOTEWORTHY Central sleep apnea (CSA) is universal during ascent to high altitude, with intermittent and transient fluctuations in oxygen saturation, but the consequences on mean sleeping blood oxygenation are unclear. We assessed indices of CSA and mean sleeping peripheral oxygen saturation ([Formula: see text]) during ascent to high altitude using two ascent profiles: rapid ascent and residence at 3,800 m and incremental ascent to 5,160 m. The severity of CSA was not correlated with mean sleeping [Formula: see text] with ascent.
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Affiliation(s)
- Jordan D Bird
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Anne Kalker
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada.,Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alexander N Rimke
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Jason S Chan
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Garrick Chan
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Gurkarn Saran
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Nicholas G Jendzjowsky
- Respiratory Medicine and Exercise Physiology, The Lundquist Institute for Biomedical Innovation, Harbor UCLA Medical Center, West Carson, California
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Thomas D Brutsaert
- Department of Exercise Science, School of Education, Syracuse University, Syracuse, New York
| | | | - Trevor A Day
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
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16
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Bader TJ, Leacy JK, Keough JRG, Ciorogariu‐Ivan A, Donald JR, Marullo AL, O’Halloran KD, Jendzjowsky NG, Wilson RJA, Day TA. The effects of acute incremental hypocapnia on the magnitude of neurovascular coupling in healthy participants. Physiol Rep 2021; 9:e14952. [PMID: 34350726 PMCID: PMC8339533 DOI: 10.14814/phy2.14952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 04/17/2021] [Indexed: 12/03/2022] Open
Abstract
The high metabolic demand of cerebral tissue requires that local perfusion is tightly coupled with local metabolic rate (neurovascular coupling; NVC). During chronic altitude exposure, where individuals are exposed to the antagonistic cerebrovascular effects of hypoxia and hypocapnia, pH is maintained through renal compensation and NVC remains stable. However, the potential independent effect of acute hypocapnia and respiratory alkalosis on NVC remains to be determined. We hypothesized that acute steady-state hypocapnia via voluntary hyperventilation would attenuate the magnitude of NVC. We recruited 17 healthy participants and insonated the posterior cerebral artery (PCA) with transcranial Doppler ultrasound. NVC was elicited using a standardized strobe light stimulus (6 Hz; 5 × 30 s on/off) where absolute delta responses from baseline (BL) in peak, mean, and total area under the curve (tAUC) were quantified. From a BL end-tidal (PET )CO2 level of 36.7 ± 3.2 Torr, participants were coached to hyperventilate to reach steady-state hypocapnic steps of Δ-5 Torr (31.6 ± 3.9) and Δ-10 Torr (26.0 ± 4.0; p < 0.001), which were maintained during the presentation of the visual stimuli. We observed a small but significant reduction in NVC peak (ΔPCAv) from BL during controlled hypocapnia at both Δ-5 (-1.58 cm/s) and Δ-10 (-1.37 cm/s), but no significant decrease in mean or tAUC NVC response was observed. These data demonstrate that acute respiratory alkalosis attenuates peak NVC magnitude at Δ-5 and Δ-10 Torr PET CO2 , equally. Although peak NVC magnitude was mildly attenuated, our data illustrate that mean and tAUC NVC are remarkably stable during acute respiratory alkalosis, suggesting multiple mechanisms underlying NVC.
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Affiliation(s)
- Taylor J. Bader
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Jack K. Leacy
- Department of PhysiologySchool of MedicineCollege of Medicine and HealthUniversity College CorkCorkIreland
| | - Joanna R. G. Keough
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | | | - Joshua R. Donald
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Anthony L. Marullo
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Ken D. O’Halloran
- Department of PhysiologySchool of MedicineCollege of Medicine and HealthUniversity College CorkCorkIreland
| | - Nicholas G. Jendzjowsky
- Division of Respiratory and Critical Care Physiology and MedicineThe Lundquist Institute for Biomedical Innovation at Harbor‐UCLA Medical CenterTorranceCAUSA
| | - Richard J. A. Wilson
- Department of Physiology and PharmacologyHotchkiss Brain InstituteCumming School of MedicineUniversity of CalgaryCalgaryABCanada
| | - Trevor A. Day
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
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17
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Mallet RT, Burtscher J, Richalet JP, Millet GP, Burtscher M. Impact of High Altitude on Cardiovascular Health: Current Perspectives. Vasc Health Risk Manag 2021; 17:317-335. [PMID: 34135590 PMCID: PMC8197622 DOI: 10.2147/vhrm.s294121] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022] Open
Abstract
Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O2, climate, individual genetic, lifestyle and socio-economic factors, as well as adaptation and acclimatization processes at high elevations are extremely complex. It is challenging to decipher the effects of these myriad factors on the cardiovascular health in high altitude residents, and even more so in those ascending to high altitudes with or without preexisting diseases. This review aims to interpret epidemiological observations in high-altitude populations; present and discuss cardiovascular responses to acute and subacute high-altitude exposure in general and more specifically in people with preexisting cardiovascular diseases; the relations between cardiovascular pathologies and neurodegenerative diseases at altitude; the effects of high-altitude exercise; and the putative cardioprotective mechanisms of hypobaric hypoxia.
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Affiliation(s)
- Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Jean-Paul Richalet
- Laboratoire Hypoxie & Poumon, UMR Inserm U1272, Université Sorbonne Paris Nord 13, Bobigny Cedex, F-93017, France
| | - Gregoire P Millet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, A-6020, Austria
- Austrian Society for Alpine and High-Altitude Medicine, Mieming, Austria
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18
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Bird JD, Leacy JK, Foster GE, Rickards CA, Wilson RJA, O'Halloran KD, Jendzjowsky NG, Pentz BA, Byman BRM, Thrall SF, Skalk AL, Hewitt SA, Steinback CD, Burns D, Ondrus P, Day TA. Time course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine days. J Appl Physiol (1985) 2021; 130:1705-1715. [PMID: 33703943 PMCID: PMC11025293 DOI: 10.1152/japplphysiol.00973.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/05/2021] [Indexed: 11/22/2022] Open
Abstract
Rapid ascent to high altitude imposes an acute hypoxic and acid-base challenge, with ventilatory and renal acclimatization countering these perturbations. Specifically, ventilatory acclimatization improves oxygenation, but with concomitant hypocapnia and respiratory alkalosis. A compensatory, renally mediated relative metabolic acidosis follows via bicarbonate elimination, normalizing arterial pH(a). The time course and magnitude of these integrated acclimatization processes are highly variable between individuals. Using a previously developed metric of renal reactivity (RR), indexing the change in arterial bicarbonate concentration (Δ[HCO3-]a; renal response) over the change in arterial pressure of CO2 (Δ[Formula: see text]; renal stimulus), we aimed to characterize changes in RR magnitude following rapid ascent and residence at altitude. Resident lowlanders (n = 16) were tested at 1,045 m (day [D]0) prior to ascent, on D2 within 24 h of arrival, and D9 during residence at 3,800 m. Radial artery blood draws were obtained to measure acid-base variables: [Formula: see text], [HCO3-]a, and pHa. Compared with D0, [Formula: see text] and [HCO3-]a were lower on D2 (P < 0.01) and D9 (P < 0.01), whereas significant changes in pHa (P = 0.072) and RR (P = 0.056) were not detected. As pHa appeared fully compensated on D2 and RR did not increase significantly from D2 to D9, these data demonstrate renal acid-base compensation within 24 h at moderate steady-state altitude. Moreover, RR was strongly and inversely correlated with ΔpHa on D2 and D9 (r≤ -0.95; P < 0.0001), suggesting that a high-gain renal response better protects pHa. Our study highlights the differential time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization following rapid ascent and residence at high altitude.NEW & NOTEWORTHY We assessed the time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization with rapid ascent and residence at 3,800 m. Despite reductions in [Formula: see text] upon ascent, pHa was normalized within 24 h of arrival at 3,800 m through renal compensation (i.e., bicarbonate elimination). Renal reactivity (RR) was unchanged between days 2 and 9, suggesting a lack of plasticity at moderate steady-state altitude. RR was strongly correlated with ΔpHa, suggesting that a high-gain renal response better protects pHa.
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Affiliation(s)
- Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jack K Leacy
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Sciences Centre, Fort Worth, Texas
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Nicholas G Jendzjowsky
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, California
| | - Brandon A Pentz
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Britta R M Byman
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Scott F Thrall
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Alexandra L Skalk
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Sarah A Hewitt
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - David Burns
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Peter Ondrus
- Department of Family Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
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19
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High-altitude illnesses: Old stories and new insights into the pathophysiology, treatment and prevention. SPORTS MEDICINE AND HEALTH SCIENCE 2021; 3:59-69. [PMID: 35782163 PMCID: PMC9219347 DOI: 10.1016/j.smhs.2021.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/11/2021] [Accepted: 04/11/2021] [Indexed: 01/19/2023] Open
Abstract
Areas at high-altitude, annually attract millions of tourists, skiers, trekkers, and climbers. If not adequately prepared and not considering certain ascent rules, a considerable proportion of those people will suffer from acute mountain sickness (AMS) or even from life-threatening high-altitude cerebral (HACE) or/and pulmonary edema (HAPE). Reduced inspired oxygen partial pressure with gain in altitude and consequently reduced oxygen availability is primarily responsible for getting sick in this setting. Appropriate acclimatization by slowly raising the hypoxic stimulus (e.g., slow ascent to high altitude) and/or repeated exposures to altitude or artificial, normobaric hypoxia will largely prevent those illnesses. Understanding physiological mechanisms of acclimatization and pathophysiological mechanisms of high-altitude diseases, knowledge of symptoms and signs, treatment and prevention strategies will largely contribute to the risk reduction and increased safety, success and enjoyment at high altitude. Thus, this review is intended to provide a sound basis for both physicians counseling high-altitude visitors and high-altitude visitors themselves.
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20
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Buchholz KJ, Burgraff NJ, Neumueller SE, Hodges MR, Pan LG, Forster HV. Physiological and neurochemical adaptations following abrupt termination of chronic hypercapnia in goats. J Appl Physiol (1985) 2021; 130:1259-1273. [PMID: 33539265 PMCID: PMC8262788 DOI: 10.1152/japplphysiol.00909.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic hypercapnia (CH) is a hallmark of respiratory diseases such as chronic obstructive pulmonary disease. In such patients, mechanical ventilation is often used to restore normal blood-gas homeostasis. However, little is known regarding physiological changes and neuroplasticity within physiological control networks after termination of CH. Utilizing our goat model of increased inspired CO2-induced CH, we determined whether termination of CH elicits time-dependent physiological and neurochemical changes within brain stem sites of physiological control. Thirty days of CH increased [Formula: see text] (+15 mmHg) and steady-state ventilation (SS V̇i; 283% of control). Within 24 h after terminating CH, SS V̇i, blood gases, arterial [H+], and most physiological measurements returned to control. However, the acute ventilatory chemoreflex (ΔV̇i/Δ[H+]) was greater than control, and measured SS V̇i exceeded ventilation predicted by arterial [H+] and ΔV̇i/Δ[H+]. Potentially contributing to these differences were increased excitatory neuromodulators serotonin and norepinephrine in the nucleus tractus solitarius, which contrasts with minimal changes observed at 24 h and 30 days of hypercapnia. Similarly, there were minimal changes found in markers of neuroinflammation and glutamate receptor-dependent neuroplasticity upon termination of CH, which were previously increased following 24 h of hypercapnia. Thus, following termination of CH: 1) ventilatory, renal, and other physiological functions rapidly return to control; 2) neuroplasticity within the ventilatory control network may contribute to the difference between measured vs. predicted ventilation and the elevation in the acute ventilatory [H+] chemoreflex; and 3) neuroplasticity is fundamentally distinct from acclimatization to CH.NEW & NOTEWORTHY In healthy adult goats, steady-state ventilation and most physiological measures return to control within 24 h after termination of chronic hypercapnia (CH). However, the acute [H+] chemoreflex is increased, and measured ventilation exceeds predicted ventilation. At 24 h of recovery, excitatory neuromodulators are above control, but other measured markers of neuroplasticity are unchanged from control. Our data suggest that CH elicits persistent physiological and neurochemical changes for up to 24 h after termination of CH.
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Affiliation(s)
- Kirstyn J. Buchholz
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Nicholas J. Burgraff
- 5Center for Integrated Brain Research, Seattle Children’s Research Institute, Seattle, Washington
| | | | - Matthew Robert Hodges
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,3Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Lawrence G. Pan
- 2Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Hubert V. Forster
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,3Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin,4Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
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21
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Effect of Carbohydrate-Electrolyte Solution Including Bicarbonate Ion Ad Libitum Ingestion on Urine Bicarbonate Retention during Mountain Trekking: A Randomized, Controlled Pilot Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18041441. [PMID: 33557035 PMCID: PMC7913653 DOI: 10.3390/ijerph18041441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 11/16/2022]
Abstract
We investigated whether bicarbonate ion (HCO3−) in a carbohydrate-electrolyte solution (CE+HCO3) ingested during climbing to 3000 m on Mount Fuji could increase urine HCO3− retention. This study was a randomized, controlled pilot study. Sixteen healthy lowlander adults were divided into two groups (six males and two females for each): a tap water (TW) group (0 kcal with no energy) and a CE+HCO3 group. The allocation to TW or CE+HCO3 was double blind. The CE solution contains 10 kcal energy, including Na+ (115 mg), K+ (78 mg), HCO3− (51 mg) per 100 mL. After collecting baseline urine and measuring body weight, participants started climbing while energy expenditure (EE) and heart rate (HR) were recorded every min with a portable calorimeter. After reaching a hut at approximately 3000 m, we collected urine and measured body weight again. The HCO3− balance during climbing, measured by subtracting the amount of urine excreted from the amount of fluid ingested, was −0.37 ± 0.77 mmol in the CE+HCO3, which was significantly higher than in the TW (−2.23 ± 0.96 mmol, p < 0.001). These results indicate that CE containing HCO3− supplementation may increase the bicarbonate buffering system during mountain trekking up to ~3000 m, suggesting a useful solution, at least, in the population of the present study on Mount Fuji.
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22
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Ju JD, Zhang C, Sgambati FP, Lopez LM, Pham LV, Schwartz AR, Accinelli RA. Acute Altitude Acclimatization in Young Healthy Volunteers: Nocturnal Oxygenation Increases Over Time, Whereas Periodic Breathing Persists. High Alt Med Biol 2020; 22:14-23. [PMID: 33185483 DOI: 10.1089/ham.2020.0009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ju, Jia-Der, Cristian Zhang, Francis P. Sgambati, Lidia M. Lopez, Luu V. Pham, Alan R. Schwartz, and Roberto A. Accinelli. Acute altitude acclimatization in young healthy volunteers: nocturnal oxygenation increases over time whereas periodic breathing persists. High Alt Med Biol. 22:14-23, 2021. Study Objectives: This study aimed to examine the acute effects of high altitude (HA) on sleep disordered breathing (sleep apnea and nocturnal hypoxemia) and acute mountain sickness and to characterize acclimatization over time. Methods: Ten native lowlanders residing at sea level (SL) completed the Lake Louise Score (LLS) and underwent nocturnal polygraphy (ApneaLink Plus) for nine consecutive nights (N1-N9) at HA (2,761 m) and two nights before and after HA. Nocturnal oxygen profiles were assessed by measuring the mean nocturnal oxyhemoglobin saturation (SpO2) during sleep, and sleep apnea severity as assessed by measuring the Apnea-Hypopnea Index (AHI). Mixed-effects linear regression was used to model responses in outcomes (mean nocturnal SpO2, logAHI, and LLS) between HA and SL. Changes in SpO2 and AHI were examined in subgroups with mild versus marked nocturnal SpO2 and low versus high AHI during exposure to HA and compared between subgroups. Results: Compared with SL, the mean nocturnal SpO2 was lower (p < 0.0001) and AHI was higher (p < 0.0001) at HA. The mean nocturnal SpO2 increased progressively (p < 0.001), whereas AHI remained high (p < 0.978) and relatively unchanged over nine successive nights at HA. Those with markedly reduced SpO2 upon arrival at HA exhibited progressive increases in the mean nocturnal SpO2 over time at HA compared with those with mild nocturnal desaturation. LLS rose at HA, but no differences were observed between subgroups. Conclusions: In healthy HA sojourners, the mean nocturnal SpO2 increased progressively over time, whereas AHI remained elevated, suggesting distinctive phenotypes and acclimatization responses to HA.
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Affiliation(s)
- Jia-Der Ju
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Cristian Zhang
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Francis P Sgambati
- Johns Hopkins Sleep Center and Center for Interdisciplinary Sleep Research Education, Baltimore, Maryland, USA
| | - Lidia M Lopez
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru.,Hospital Cayetano Heredia, Lima, Perú
| | - Luu V Pham
- Johns Hopkins Sleep Center and Center for Interdisciplinary Sleep Research Education, Baltimore, Maryland, USA.,Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Alan R Schwartz
- Adjunct Professor, Perelman School of Medicine, University of Pennsylvania, Lima, Perú.,Distinguished Visiting Professor, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Roberto A Accinelli
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru.,Hospital Cayetano Heredia, Lima, Perú
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23
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Holmström PK, Bird JD, Thrall SF, Kalker A, Herrington BA, Soriano JE, Mann LM, Rampuri ZH, Brutsaert TD, Karlsson Ø, Sherpa MT, Schagatay EKA, Day TA. The effects of high altitude ascent on splenic contraction and the diving response during voluntary apnoea. Exp Physiol 2020; 106:160-174. [DOI: 10.1113/ep088571] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 09/03/2020] [Indexed: 12/30/2022]
Affiliation(s)
| | - Jordan D. Bird
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Scott F. Thrall
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Ann Kalker
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Radboud University Nijmegen Netherlands
| | - Brittney A. Herrington
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jan E. Soriano
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Leah M. Mann
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Zahrah H. Rampuri
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Tom D. Brutsaert
- Department of Exercise Science Syracuse University Syracuse NY USA
| | - Øyvind Karlsson
- Swedish Winter Sports Research Centre Mid Sweden University Östersund Sweden
| | | | - Erika K. A. Schagatay
- Department of Health Sciences Mid Sweden University Östersund Sweden
- Swedish Winter Sports Research Centre Mid Sweden University Östersund Sweden
| | - Trevor A. Day
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
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24
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Steele AR, Tymko MM, Meah VL, Simpson LL, Gasho C, Dawkins TG, Villafuerte FC, Ainslie PN, Stembridge M, Moore JP, Steinback CD. Global REACH 2018: renal oxygen delivery is maintained during early acclimatization to 4,330 m. Am J Physiol Renal Physiol 2020; 319:F1081-F1089. [PMID: 32996319 DOI: 10.1152/ajprenal.00372.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Early acclimatization to high altitude is characterized by various respiratory, hematological, and cardiovascular adaptations that serve to restore oxygen delivery to tissue. However, less is understood about renal function and the role of renal oxygen delivery (RDO2) during high altitude acclimatization. We hypothesized that 1) RDO2 would be reduced after 12 h of high altitude exposure (high altitude day 1) but restored to sea level values after 1 wk (high altitude day 7) and 2) RDO2 would be associated with renal reactivity, an index of acid-base compensation at high altitude. Twenty-four healthy lowlander participants were tested at sea level (344 m, Kelowna, BC, Canada) and on day 1 and day 7 at high altitude (4,330 m, Cerro de Pasco, Peru). Cardiac output, renal blood flow, and arterial and venous blood sampling for renin-angiotensin-aldosterone system hormones and NH2-terminal pro-B-type natriuretic peptides were collected at each time point. Renal reactivity was calculated as follows: (Δarterial bicarbonate)/(Δarterial Pco2) between sea level and high altitude day 1 and sea level and high altitude day 7. The main findings were that 1) RDO2 was initially decreased at high altitude compared with sea level (ΔRDO2: -22 ± 17%, P < 0.001) but was restored to sea level values on high altitude day 7 (ΔRDO2: -6 ± 14%, P = 0.36). The observed improvements in RDO2 resulted from both changes in renal blood flow (Δ from high altitude day 1: +12 ± 11%, P = 0.008) and arterial oxygen content (Δ from high altitude day 1: +44.8 ± 17.7%, P = 0.006) and 2) renal reactivity was positively correlated with RDO2 on high altitude day 7 (r = 0.70, P < 0.001) but not high altitude day 1 (r = 0.26, P = 0.29). These findings characterize the temporal responses of renal function during early high altitude acclimatization and the influence of RDO2 in the regulation of acid-base balance.
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Affiliation(s)
- Andrew R Steele
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Michael M Tymko
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Victoria L Meah
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom
| | - Christopher Gasho
- Division of Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, California
| | - Tony G Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Francisco C Villafuerte
- Department of Biological and Physiological Sciences, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Michael Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Jonathan P Moore
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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25
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Palubiski LM, O'Halloran KD, O'Neill J. Renal Physiological Adaptation to High Altitude: A Systematic Review. Front Physiol 2020; 11:756. [PMID: 32765289 PMCID: PMC7378794 DOI: 10.3389/fphys.2020.00756] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 06/11/2020] [Indexed: 11/15/2022] Open
Abstract
Background: Under normal physiological conditions, renal tissue oxygen is tightly regulated. At high altitude, a physiological challenge is imposed by the decrease in atmospheric oxygen. At the level of the kidney, the physiological adaptation to high altitude is poorly understood, which might relate to different integrated responses to hypoxia over different time domains of exposure. Thus, this systematic review sought to examine the renal physiological adaptation to high altitude in the context of the magnitude and duration of exposure to high altitude in the healthy kidney model. Methods: To conduct the review, three electronic databases were examined: OVID, PubMed, and Scopus. Search terms included: Altitude, renal, and kidney. The broad, but comprehensive search, retrieved 1,057 articles published between 1997 and April 2020. Fourteen studies were included in the review. Results: The inconsistent effect of high altitude on renal hemodynamic parameters (glomerular filtration rate, renal blood flow, and renal plasma flow), electrolyte balance, and renal tissue oxygen is difficult to interpret; however, the data suggest that the nature and extent of renal physiological adaptation at high altitude appears to be related to the magnitude and duration of the exposure. Conclusion: It is clear that renal physiological adaptation to high altitude is a complex process that is not yet fully understood. Further research is needed to better understand the renal physiological adaptation to hypoxia and how renal oxygen homeostasis and metabolism is defended during exposure to high altitude and affected as a long-term consequence of renal adaptation at high altitude.
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Affiliation(s)
- Lisa M Palubiski
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Julie O'Neill
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
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26
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Leacy JK, Linares AM, Zouboules SM, Rampuri ZH, Bird JD, Herrington BA, Mann LM, Soriano JE, Thrall SF, Kalker A, Brutsaert TD, O'Halloran KD, Sherpa MT, Day TA. Cardiorespiratory hysteresis during incremental high‐altitude ascent–descent quantifies the magnitude of ventilatory acclimatization. Exp Physiol 2020; 106:139-150. [DOI: 10.1113/ep088488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/13/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Jack K. Leacy
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | - Andrea M. Linares
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Shaelynn M. Zouboules
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Zahrah H. Rampuri
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jordan D. Bird
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Brittney A. Herrington
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Leah M. Mann
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jan E. Soriano
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Scott F. Thrall
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Anne Kalker
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Radboud University Nijmegen The Netherlands
| | | | - Ken D. O'Halloran
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | | | - Trevor A. Day
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
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27
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Walsh JJ, Drouin PJ, King TJ, D'Urzo KA, Tschakovsky ME, Cheung SS, Day TA. Acute aerobic exercise impairs aspects of cognitive function at high altitude. Physiol Behav 2020; 223:112979. [PMID: 32479806 DOI: 10.1016/j.physbeh.2020.112979] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/28/2019] [Accepted: 05/20/2020] [Indexed: 12/24/2022]
Abstract
Hypoxia-mediated cognitive dysfunction can be transiently mitigated by exercise in a laboratory-based setting. Whether this effect holds true in the context of high altitude hypoxia has not been determined. We investigated the effect of acute aerobic exercise on cognitive function (CF) at low (1400m) and high altitude (4240m). Fifteen volunteers (24.1±3.5yrs; 9 females) exercised for 20-min at 40-60% of their heart rate reserve at low and high altitude. CF was assessed before and 10-min after exercise using a tablet-based battery of executive function tests. A sea-level control group (n=13; 24.2±2.4 years; 9 females) performed time-matched CF tests to assess the contribution of a learning effects due to repeated testing. Measures of resting CF were unaffected by ascent to high altitude. Following high altitude exercise, performance significantly worsened on the digit symbol substitution task - a test of processing speed, working memory, and visuospatial attention (z=0.01 vs. -0.59, p=0.02, η2=0.35). No effect was found on other measures of CF following exercise. There was no association between changes in peripheral oxygen saturation and changes in CF following high altitude exercise (r=0.22, p=0.44), but higher hemoglobin concentration at high altitude was associated with a decline in CF following exercise at high altitude (r=-0.65, p=0.02). Acute aerobic exercise performed at high altitude impairs some aspects of CF, whereas other CF tests remain unchanged. The strong ecological validity of this study warrants attention and follow-up investigations are needed to better characterize selective impairment of CF with high altitude exercise.
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Affiliation(s)
- Jeremy J Walsh
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada; School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada.
| | - Patrick J Drouin
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Trevor J King
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada; Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Katrina A D'Urzo
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | | | - Stephen S Cheung
- Department of Kinesiology, Brock University, St. Catherines, ON, Canada
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, AB, Canada
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28
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Zavhorodnia VA, Androshchuk OI, Kharchenko TH, Kudii LI, Kovalenko SO. Haemodynamic effects of hyperventilation on healthy men with different levels of autonomic tone. REGULATORY MECHANISMS IN BIOSYSTEMS 2020. [DOI: 10.15421/022002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The topicality of the research is stipulated by insufficient study of the correlation between the functional state of the cardiorespiratory system and autonomic tone. The goal of the research was to analyze the changes of central haemodynamics with 10-minute regulated breathing at the rate of 30 cycles per minute and within 40 minutes of recovery after the test in healthy young men with different levels of autonomic tone. Records of the chest rheoplethysmogram were recorded on a rheograph KhAI-medica standard (KhAI-medica, Kharkiv, Ukraine), a capnogram - in a lateral flow on a infrared capnograph (Datex, Finland), and the duration of R-R intervals was determined by a Polar WIND Link in the program of Polar Protrainer 5.0 (Polar Electro OY, Finland). Systolic and diastolic blood pressure were measured by Korotkov’s auscultatory method by mercury tonometer (Riester, Germany). The indicator of the normalized power of the spectrum in the range of 0.15–0.40 Hz was evaluated by 5-minute records; three groups of persons were distinguished according to its distribution at rest by the method of signal deviation, namely, sympathicotonic, normotonic and parasympathicotonic. The initial level of autonomic tone was found to impact the dynamics of СО2 level in alveolar air during hyperventilation and during recovery thereafter. Thus, PetCО2 was higher (41.3 mm Hg) in parasympathicotonic than in sympathicotonic (39.3 mm Hg) and normotonic (39.5 mm Hg) persons. During the test, R-R interval duration decreased being more expressed in normotonic persons. At the same time, the heart index was found to increase in three groups, and general peripheral resistance – to decrease mostly in normo- and parasympathicotonic persons. In addition, the reliable increase of stroke index and heart index was found in these groups. In the recovery period after hyperventilation, the decrease of tension index and ejection speed was found in normo- and, particularly, parasympathicotonic compared with sympathicotonic men and the increase of tension phase and ejection phase duration.
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Verratti V, Mrakic-Sposta S, Moriggi M, Tonacci A, Bhandari S, Migliorelli D, Bajracharya A, Bondi D, Agrò EF, Cerretelli P. Urinary physiology and hypoxia: a pilot study of moderate-altitude trekking effects on urodynamic indexes. Am J Physiol Renal Physiol 2019; 317:F1081-F1086. [DOI: 10.1152/ajprenal.00333.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exposure to high altitude is one of the most widely used models to study the adaptive response to hypoxia in humans. However, little is known about the related effects on micturition. The present study addresses the adaptive urinary responses in four healthy adult lowlanders, comparing urodynamic indexes at Kathmandu [1,450 m above sea level (a.s.l.); K1450] and during a sojourn in Namche Bazar (3,500 m a.s.l.; NB3500). The urodynamic testing consisted of cistomanometry and bladder pressure/flow measurements. Anthropometrics, electrocardiographic, and peripheral capillary oxygen saturation data were also collected. The main findings consisted of significant reductions in bladder power at maximum urine flow by ~30%, bladder contractility index by 13%, and infused volume both at first (by 57%) and urgency sensation (by 14%) to urinate, indicating a reduced cystometric capacity, at NB3500. In addition to the urinary changes, we found that oxygen saturation, body mass index, body surface area, and median RR time were all significantly reduced at altitude. We submit that the hypoxia-related parasympathetic inhibition could be the underlying mechanism of both urodynamic and heart rate adaptive responses to high-altitude exposure. Moreover, increased diuresis and faster bladder filling at altitude may trigger the anticipation of being able to void, a common cause of urgency. We believe that the present pilot study represents an original approach to the study of urinary physiology at altitude.
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Affiliation(s)
- Vittore Verratti
- Department of Psychological Sciences, Health, and Territory, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy
- Laboratory of Clinical and Hypoxic Physiology, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy
| | - Simona Mrakic-Sposta
- Institute of Bioimaging and Molecular Physiology, National Research Council of Italy, Segrate, Italy
| | - Manuela Moriggi
- Institute of Bioimaging and Molecular Physiology, National Research Council of Italy, Segrate, Italy
| | - Alessandro Tonacci
- Institute of Clinical Physiology, National Research Council of Italy, Pisa, Italy
| | - Suwas Bhandari
- Wenzhou Medical University, Wenzhou, Zhejiang Province, China
| | | | | | - Danilo Bondi
- Department of Neuroscience, Imaging, and Clinical Sciences, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy
| | - Enrico Finazzi Agrò
- Department of Surgical Sciences, University of Rome “Tor Vergata” and Unit of Urology Policlinic, Tor Vergata University Hospital, Rome, Italy
| | - Paolo Cerretelli
- Institute of Bioimaging and Molecular Physiology, National Research Council of Italy, Segrate, Italy
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Steady-state cerebral blood flow regulation at altitude: interaction between oxygen and carbon dioxide. Eur J Appl Physiol 2019; 119:2529-2544. [DOI: 10.1007/s00421-019-04206-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 08/06/2019] [Indexed: 02/07/2023]
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Acid-Base Disturbances in Patients with Asthma: A Literature Review and Comments on Their Pathophysiology. J Clin Med 2019; 8:jcm8040563. [PMID: 31027265 PMCID: PMC6518237 DOI: 10.3390/jcm8040563] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/19/2019] [Accepted: 04/23/2019] [Indexed: 01/19/2023] Open
Abstract
Asthma is a common illness throughout the world that affects the respiratory system function, i.e., a system whose operational adequacy determines the respiratory gases exchange. It is therefore expected that acute severe asthma will be associated with respiratory acid-base disorders. In addition, the resulting hypoxemia along with the circulatory compromise due to heart–lung interactions can reduce tissue oxygenation, with a particular impact on respiratory muscles that have increased energy needs due to the increased workload. Thus, anaerobic metabolism may ensue, leading to lactic acidosis. Additionally, chronic hypocapnia in asthma can cause a compensatory drop in plasma bicarbonate concentration, resulting in non-anion gap acidosis. Indeed, studies have shown that in acute severe asthma, metabolic acid-base disorders may occur, i.e., high anion gap or non-anion gap metabolic acidosis. This review briefly presents studies that have investigated acid-base disorders in asthma, with comments on their underlying pathophysiology.
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Zouboules SM, Day TA. The exhausting work of acclimating to chronically elevated CO 2. J Physiol 2019; 597:1421-1423. [PMID: 30635913 DOI: 10.1113/jp277491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Shaelynn M Zouboules
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
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Leacy JK, Zouboules SM, Mann CR, Peltonen JDB, Saran G, Nysten CE, Nysten HE, Brutsaert TD, O’Halloran KD, Sherpa MT, Day TA. Neurovascular Coupling Remains Intact During Incremental Ascent to High Altitude (4240 m) in Acclimatized Healthy Volunteers. Front Physiol 2018; 9:1691. [PMID: 30546319 PMCID: PMC6279846 DOI: 10.3389/fphys.2018.01691] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/09/2018] [Indexed: 12/21/2022] Open
Abstract
Neurovascular coupling (NVC) is the temporal link between neuronal metabolic activity and regional cerebral blood flow (CBF), supporting adequate delivery of nutrients. Exposure to high altitude (HA) imposes several stressors, including hypoxia and hypocapnia, which modulate cerebrovascular tone in an antagonistic fashion. Whether these contrasting stressors and subsequent adaptations affect NVC during incremental ascent to HA is unclear. The aim of this study was to assess whether incremental ascent to HA influences the NVC response. Given that CBF is sensitive to changes in arterial blood gasses, in particular PaCO2, we hypothesized that the vasoconstrictive effect of hypocapnia during ascent would decrease the NVC response. 10 healthy study participants (21.7 ± 1.3 years, 23.57 ± 2.00 kg/m2, mean ± SD) were recruited as part of a research expedition to HA in the Nepal Himalaya. Resting posterior cerebral artery velocity (PCAv), arterial blood gasses (PaO2, SaO2, PaCO2, [HCO3 -], base excess and arterial blood pH) and NVC response of the PCA were measured at four pre-determined locations: Calgary/Kathmandu (1045/1400 m, control), Namche (3440 m), Deboche (3820 m) and Pheriche (4240 m). PCAv was measured using transcranial Doppler ultrasound. Arterial blood draws were taken from the radial artery and analyzed using a portable blood gas/electrolyte analyzer. NVC was determined in response to visual stimulation (VS; Strobe light; 6 Hz; 30 s on/off × 3 trials). The NVC response was averaged across three VS trials at each location. PaO2, SaO2, and PaCO2 were each significantly decreased at 3440, 3820, and 4240 m. No significant differences were found for pH at HA (P > 0.05) due to significant reductions in [HCO3 -] (P < 0.043). As expected, incremental ascent to HA induced a state of hypoxic hypocapnia, whereas normal arterial pH was maintained due to renal compensation. NVC was quantified as the delta (Δ) PCAv from baseline for mean PCAv, peak PCAv and total area under the curve (ΔPCAv tAUC) during VS. No significant differences were found for Δmean, Δpeak or ΔPCAv tAUC between locations (P > 0.05). NVC remains remarkably intact during incremental ascent to HA in healthy acclimatized individuals. Despite the array of superimposed stressors associated with ascent to HA, CBF and NVC regulation may be preserved coincident with arterial pH maintenance during acclimatization.
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Affiliation(s)
- Jack K. Leacy
- Department of Biology, Mount Royal University, Calgary, AB, Canada
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | | | - Carli R. Mann
- Department of Biology, Mount Royal University, Calgary, AB, Canada
| | | | - Gurkan Saran
- Department of Biology, Mount Royal University, Calgary, AB, Canada
| | | | | | - Tom D. Brutsaert
- School of Education, Syracuse University, Syracuse, NY, United States
| | - Ken D. O’Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | | | - Trevor A. Day
- Department of Biology, Mount Royal University, Calgary, AB, Canada
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