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Ivy CM, Young KG, Qu M, Dick MF, Shoemaker JK, Guglielmo CG. The catecholamine response to graded high-altitude flight in yellow-rumped warblers ( Setophaga coronata). Am J Physiol Regul Integr Comp Physiol 2025; 328:R329-R340. [PMID: 39929197 DOI: 10.1152/ajpregu.00197.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Revised: 09/11/2024] [Accepted: 01/30/2025] [Indexed: 03/04/2025]
Abstract
Chronic exposure to low oxygen (hypoxia) leads to amplification of the hypoxic chemoreflex, increasing breathing and sympathetic nervous system (SNS) activation. Prolonged SNS activation redistributes blood to hypoxia-sensitive tissues away from muscles. Recent tracking studies have shown that migratory songbirds can fly 5,000 m or higher above sea level, leading us to hypothesize that migratory birds may have a blunted hypoxic chemoreflex to maintain blood flow to muscles during migratory flight at high altitudes. To test this hypothesis, we used a hypobaric wind tunnel and measured circulating plasma catecholamines after maximal altitude flight, flight at 75% of maximal altitude, flight at ground level (∼250 m), and after rest at 75% of maximal altitude and ground level in migratory myrtle yellow-rumped warblers (Setophaga coronata). Yellow-rumped warblers were capable of flying above 4,000 m simulated altitude above sea level (average maximum altitude of ∼3,600 m) and would maintain flights at 75% of individual maximum altitudes (∼2,700 m). Circulating dopamine and noradrenaline were similar between resting and flight conditions at ground level and with exposure to 75% of maximal altitude, whereas adrenaline significantly increased with flight, but did not change further with flight at 75% of maximal altitude. In contrast, both adrenaline and noradrenaline concentrations increased after maximum altitude flights compared with 75% and ground-level flights. Our findings show that exercise increases plasma adrenaline in migratory songbirds and suggest that warblers flying at high altitudes below their maximum altitude may be minimally hypoxic, allowing them to maintain oxygen transport to flight muscles.NEW & NOTEWORTHY Yellow-rumped warblers, a small songbird that conducts migratory flights, were found to fly to altitudes above 4,000 m above sea level in simulated flights using a hypobaric wind tunnel. Circulating adrenaline suggests that warblers flying at 75% of individual maximum altitudes are not experiencing arterial hypoxia, allowing them to maintain aerobically demanding migratory flight at high altitudes.
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Affiliation(s)
- Catherine M Ivy
- Department of Biology, Centre for Animals on the Move, Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Kevin G Young
- Department of Biology, Centre for Animals on the Move, Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Melanie Qu
- Department of Biology, Centre for Animals on the Move, Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Morag F Dick
- Department of Biology, Centre for Animals on the Move, Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - J Kevin Shoemaker
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Niewinski P, Tubek S, Josiak K, Nowak K, Ponikowski P. Cardiac parasympathetic denervation reduces hypoxic tachycardia, baroreflex sensitivity and heart rate variability in humans. Sci Rep 2025; 15:6633. [PMID: 39994437 PMCID: PMC11850868 DOI: 10.1038/s41598-025-91214-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 02/18/2025] [Indexed: 02/26/2025] Open
Abstract
The autonomic regulation of heart rate (HR) reactivity to acute hypoxia remains unclear. Parasympathetic cardioneuroablation (PCNA) may serve as a novel model for the analysis of physiological consequences of reduced vagal influence over sinus node in humans. We studied 11 adult patients scheduled for PCNA for the treatment of vasovagal syncope. HR reactivity to hypoxia was studied before and after PCNA with brief nitrogen gas administrations. Each test was followed by an atropine challenge to evaluate the contribution of parasympathetic tone to the resting HR. Additionally, we assessed changes in cardiac baroreflex sensitivity and HR variability following the procedure. PCNA led to partial parasympathetic denervation of sinus node at rest (67.0 ± 20.1%). This translated into a significant change in HR reactivity to hypoxia (0.58 ± 0.21 vs. 0.22 ± 0.13 beats min- 1%SpO2 - 1, p = 0.0001) which was proportional to the degree of cardiac vagal denervation (R = 0.76, p = 0.01). There was no change in peak HR on atropine following PCNA implying unchanged sympathetic input to sinus node. This suggests that HR reactivity to acute hypoxia is significantly influenced by parasympathetic system. Additionally, despite incomplete vagal denervation PCNA resulted in profoundly depressed HR variability and cardiac baroreflex sensitivity. The clinical meaning of the latter should be explored in further studies.
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Affiliation(s)
- Piotr Niewinski
- Institute of Heart Diseases, Wrocław Medical University, Ul. Borowska 213, 50-556, Wrocław, Poland.
- Clinical Department of Cardiology, Jan Mikulicz Radecki University Hospital in Wrocław, Wrocław, Poland.
| | - Stanislaw Tubek
- Institute of Heart Diseases, Wrocław Medical University, Ul. Borowska 213, 50-556, Wrocław, Poland
- Clinical Department of Cardiology, Jan Mikulicz Radecki University Hospital in Wrocław, Wrocław, Poland
| | - Krystian Josiak
- Department of Cardiology, 4th Military Hospital in Wrocław, Wrocław, Poland
| | - Krzysztof Nowak
- Institute of Heart Diseases, Wrocław Medical University, Ul. Borowska 213, 50-556, Wrocław, Poland
- Clinical Department of Cardiology, Jan Mikulicz Radecki University Hospital in Wrocław, Wrocław, Poland
| | - Piotr Ponikowski
- Institute of Heart Diseases, Wrocław Medical University, Ul. Borowska 213, 50-556, Wrocław, Poland
- Clinical Department of Cardiology, Jan Mikulicz Radecki University Hospital in Wrocław, Wrocław, Poland
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Michno M, Schmitz J, Foerges AL, Beer S, Jordan J, Neumaier B, Drzezga A, Aeschbach D, Bauer A, Tank J, Weis H, Elmenhorst EM, Elmenhorst D. Effect of Acute Hypoxia Exposure on the Availability of A 1 Adenosine Receptors and Perfusion in the Human Brain. J Nucl Med 2024:jnumed.124.268455. [PMID: 39667818 DOI: 10.2967/jnumed.124.268455] [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: 07/22/2024] [Accepted: 11/05/2024] [Indexed: 12/14/2024] Open
Abstract
In animal studies it has been observed that the inhibitory neuromodulator adenosine is released into the cerebral interstitial space during hypoxic challenges. Adenosine's actions on the A1 adenosine receptor (A1AR) protect the brain from oxygen deprivation and overexertion through adjustments in cerebral blood flow, metabolism, and electric activity. Methods: Using 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propylxanthine ([18F]CPFPX), a PET tracer for the A1AR, we tested the hypothesis that hypoxia-induced adenosine release reduces A1AR availability in the human brain. Furthermore, we investigated whether this response is associated with altered brain perfusion and psychomotor vigilance. Ten healthy volunteers completed a 110-min bolus-plus-constant-infusion [18F]CPFPX PET/MRI hybrid experiment including a 30-min interval of normobaric hypoxia with peripheral oxygen saturation between 70% and 75%. We obtained blood samples to calculate metabolite-corrected steady-state A1AR distribution volumes and measured gray matter brain perfusion via arterial spin labeling in high temporal resolution. A 3-min psychomotor vigilance test was conducted every 10 min, and heart rate and peripheral blood oxygen saturation were continuously measured. Results: In all 7 examined brain regions, hypoxia reduced A1AR availability significantly (e.g., frontal lobe, 13.5%; P = 0.0144) whereas gray matter brain perfusion increased (e.g., frontal lobe, 42.5%; P = 0.0007). Heart rate increased by 19% (P = 0.0039). Mean reaction speed decreased by 4.3% (P = 0.0021). Conclusion: Our study is the first, to our knowledge, to demonstrate that acute hypoxia, corresponding to a mean altitude of 5,500 m (18,000 ft), reduces A1AR availability in the human brain. The finding is consistent with hypoxia-induced cerebral adenosine release leading to increased A1AR occupancy.
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Affiliation(s)
- Manuel Michno
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany
| | - Jan Schmitz
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Cologne, Cologne, Germany
| | - Anna L Foerges
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany
| | - Simone Beer
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany
| | - Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Medical Faculty, University of Cologne, Cologne, Germany
| | - Bernd Neumaier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Forschungszentrum Jülich, Jülich, Germany
| | - Alexander Drzezga
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
- German Center for Neurodegenerative Diseases, Bonn-Cologne, Germany
| | - Daniel Aeschbach
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Institute of Experimental Epileptology and Cognition Research, University of Bonn Medical Center, Bonn, Germany; and
| | - Andreas Bauer
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany
| | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Henning Weis
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Eva-Maria Elmenhorst
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Institute for Occupational, Social, and Environmental Medicine, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - David Elmenhorst
- Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich, Jülich, Germany;
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
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Persson PB, Persson AB. Evolutionary physiology. Acta Physiol (Oxf) 2024; 240:e14221. [PMID: 39207025 DOI: 10.1111/apha.14221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Accepted: 08/14/2024] [Indexed: 09/04/2024]
Affiliation(s)
- Pontus B Persson
- Institute of Translational Physiology, Freie Universität Berlin and Humboldt-Universität zu Berlin, Charité-Universitätsmedizin Berlin
| | - Anja Bondke Persson
- Freie Universität Berlin and Humboldt-Universität zu Berlin, Charité-Universitätsmedizin Berlin
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Vornanen M, Badr A, Haverinen J. Cardiac arrhythmias in fish induced by natural and anthropogenic changes in environmental conditions. J Exp Biol 2024; 227:jeb247446. [PMID: 39119881 DOI: 10.1242/jeb.247446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
A regular heartbeat is essential for maintaining the homeostasis of the vertebrate body. However, environmental pollutants, oxygen deficiency and extreme temperatures can impair heart function in fish. In this Review, we provide an integrative view of the molecular origins of cardiac arrhythmias and their functional consequences, from the level of ion channels to cardiac electrical activity in living fish. First, we describe the current knowledge of the cardiac excitation-contraction coupling of fish, as the electrical activity of the heart and intracellular Ca2+ regulation act as a platform for cardiac arrhythmias. Then, we compile findings on cardiac arrhythmias in fish. Although fish can experience several types of cardiac arrhythmia under stressful conditions, the most typical arrhythmia in fish - both under heat stress and in the presence of toxic substances - is atrioventricular block, which is the inability of the action potential to progress from the atrium to the ventricle. Early and delayed afterdepolarizations are less common in fish hearts than in the hearts of endotherms, perhaps owing to the excitation-contraction coupling properties of the fish heart. In fish hearts, Ca2+-induced Ca2+ release from the sarcoplasmic reticulum plays a smaller role than Ca2+ influx through the sarcolemma. Environmental changes and ion channel toxins can induce arrhythmias in fish and weaken their tolerance to environmental stresses. Although different from endotherm hearts in many respects, fish hearts can serve as a translational model for studying human cardiac arrhythmias, especially for human neonates.
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Affiliation(s)
- Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
| | - Ahmed Badr
- Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
- Department of Zoology, Faculty of Science, Sohag University, 82524 Sohag, Egypt
| | - Jaakko Haverinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
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Zhang L, Zhao X, Wang Z, Deng H, Zhang X, Wang X, Lao J, Gao M, Hou Y, Han Y. Preadmission metformin use increased the incidence of hyperlactatemia at admission and 30-day in-hospital mortality among T2D patients with heart disease at high risk of hypoxia. Int J Cardiol 2024; 412:132338. [PMID: 38964551 DOI: 10.1016/j.ijcard.2024.132338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 06/27/2024] [Accepted: 07/01/2024] [Indexed: 07/06/2024]
Abstract
BACKGROUND Surprisingly, despite the high prevalence of metformin use in type 2 diabetes (T2D) patients with heart disease, limited safety data is available regarding metformin use in patients with acute and critical heart disease. METHODS In this single-center retrospective study, patients admitted to the cardiology department for heart failure (HF) or acute coronary syndrome (ACS) between December 2013 and December 2021 and who underwent arterial blood gas analysis at admission with an estimated glomerular clearance rate of ≥45 ml/min/1.73 m2 were identified. The incidences of hyperlactatemia, acidosis, and 30-day in-hospital mortality were compared between preadmission metformin users and nonusers. RESULTS Of 526 admissions, 193/193 metformin users/nonusers were selected in a propensity score-matched model. Metformin users had greater lactate levels (2.55 ± 2.07 mmol/l vs. 2.00 ± 1.80 mmol/l P < 0.01), a greater incidence of hyperlactatemia [odds ratio (OR) = 2.55; 95% confidence interval (CI), 1.63-3.98; P < 0.01] and acidosis (OR = 1.78; 95% CI, 1.00-3.16; P < 0.05) at admission and a greater incidence of in-hospital mortality (OR = 3.83; 95% CI, 1.05-13.94; P < 0.05), especially those with HF/acute myocardial infarction, elderly age, or without preadmission insulin use. CONCLUSIONS Our results suggest that, compared to metformin nonusers, preadmission use of metformin may be associated with a greater incidence of hyperlactatemia and acidosis at admission and greater 30-day in-hospital mortality among T2D patients with HF or ACS at high risk of hypoxia, particularly those without preadmission insulin use. The safety of metformin in this population needs to be confirmed in prospective controlled trials.
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Affiliation(s)
- Le Zhang
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China
| | - Xia Zhao
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China
| | - Zhongsu Wang
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China
| | - Hao Deng
- School of Pharmacy, Shandong University, Jinan, Shandong Province, PR China
| | - Xue Zhang
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China
| | - Xuan Wang
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China
| | - Jiahui Lao
- Health and Medicine, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, Shandong Province, PR China
| | - Mei Gao
- Department of Cardiology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Cardiac Electrophysiology and Arrhythmia, Jinan, Shandong Province, PR China
| | - Yinglong Hou
- Department of Cardiology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Cardiac Electrophysiology and Arrhythmia, Jinan, Shandong Province, PR China
| | - Yi Han
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, Shandong Province, PR China.
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7
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Moya EA, Yu JJ, Brown S, Gu W, Lawrence ES, Carlson R, Brandes A, Wegeng W, Amann K, McIntosh SE, Powell FL, Simonson TS. Tibetans exhibit lower hemoglobin concentration and decreased heart response to hypoxia during poikilocapnia at intermediate altitude relative to Han Chinese. Front Physiol 2024; 15:1334874. [PMID: 38784113 PMCID: PMC11112024 DOI: 10.3389/fphys.2024.1334874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 04/09/2024] [Indexed: 05/25/2024] Open
Abstract
Background High-altitude populations exhibit distinct cellular, respiratory, and cardiovascular phenotypes, some of which provide adaptive advantages to hypoxic conditions compared to populations with sea-level ancestry. Studies performed in populations with a history of high-altitude residence, such as Tibetans, support the idea that many of these phenotypes may be shaped by genomic features that have been positively selected for throughout generations. We hypothesize that such traits observed in Tibetans at high altitude also occur in Tibetans living at intermediate altitude, even in the absence of severe sustained hypoxia. Methodology We studied individuals of high-altitude ancestry (Tibetans, n = 17 females; n = 12 males) and sea-level ancestry (Han Chinese, n = 6 females; n = 10 males), both who had been living at ∼1300 m (∼4327 ft) for at least 18 months. We measured hemoglobin concentration ([Hb]), hypoxic ventilatory response (HVR), and hypoxic heart rate response (HHRR) with end-tidal CO2 (PetCO2) held constant (isocapnia) or allowed to decrease with hypoxic hyperventilation (poikilocapnia). We also quantified the contribution of CO2 on ventilation and heart rate by calculating the differences of isocapnic versus poikilocapnic hypoxic conditions (Δ V ˙ I /ΔPetCO2 and ΔHR/ΔPetCO2, respectively). Results Male Tibetans had lower [Hb] compared to Han Chinese males (p < 0.05), consistent with reports for individuals from these populations living at high altitude and sea level. Measurements of ventilation (resting ventilation, HVR, and PetCO2) were similar for both groups. Heart rate responses to hypoxia were similar in both groups during isocapnia; however, HHRR in poikilocapnia was reduced in the Tibetan group (p < 0.03), and the heart rate response to CO2 in hypoxia was lower in Tibetans relative to Han Chinese (p < 0.01). Conclusion These results suggest that Tibetans living at intermediate altitude have blunted cardiac responses in the context of hypoxia. Hence, only some of the phenotypes observed in Tibetans living at high altitude are observed in Tibetans living at intermediate altitude. Whereas blunted cardiac responses to hypoxia is revealed at intermediate altitudes, manifestation of other physiological adaptations to high altitude may require exposure to more severe levels of hypoxia.
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Affiliation(s)
- E. A. Moya
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - J. J. Yu
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - S. Brown
- Department of Anesthesiology, Loyola University Medical Center, Maywood, IL, United States
| | - W. Gu
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - E. S. Lawrence
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - R. Carlson
- School of Medicine, University of Utah, Salt Lake City, UT, United States
| | - A. Brandes
- School of Medicine, University of Utah, Salt Lake City, UT, United States
| | - W. Wegeng
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - K. Amann
- Department of Emergency Medicine, University of Rochester Medical Center, Rochester, NY, United States
| | - S. E. McIntosh
- Department of Emergency Medicine, University of Utah Health, Salt Lake City, UT, United States
| | - F. L. Powell
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - T. S. Simonson
- Division of Pulmonary, Critical Care, Sleep Medicine, and Physiology, Department of Medicine, University of California San Diego, La Jolla, CA, United States
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Palstra AP, Abbink W, Agbeti WEK, Kruijt L, Jéhannet P, Lankheet MJ. Heart Rate and Acceleration Dynamics during Swim-Fitness and Stress Challenge Tests in Yellowtail Kingfish ( Seriola lalandi). BIOLOGY 2024; 13:189. [PMID: 38534458 DOI: 10.3390/biology13030189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 03/28/2024]
Abstract
The yellowtail kingfish is a highly active and fast-growing marine fish with promising potential for aquaculture. In this study, essential insights were gained into the energy economy of this species by heart rate and acceleration logging during a swim-fitness test and a subsequent stress challenge test. Oxygen consumption values of the 600-800 g fish, when swimming in the range of 0.2 up to 1 m·s-1, were high-between 550 and 800 mg·kg-1·h-1-and the heart rate values-up to 228 bpm-were even among the highest ever measured for fishes. When swimming at these increasing speeds, their heart rate increased from 126 up to 162 bpm, and acceleration increased from 11 up to 26 milli-g. When exposed to four sequential steps of increasing stress load, the decreasing peaks of acceleration (baseline values of 12 to peaks of 26, 19 and 15 milli-g) indicated anticipatory behavior, but the heart rate increases (110 up to 138-144 bpm) remained similar. During the fourth step, when fish were also chased, peaking values of 186 bpm and 44 milli-g were measured. Oxygen consumption and heart rate increased with swimming speed and was well reflected by increases in tail beat and head width frequencies. Only when swimming steadily near the optimal swimming speed were these parameters strongly correlated.
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Affiliation(s)
- Arjan P Palstra
- Animal Breeding and Genomics, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
| | - Wout Abbink
- Animal Breeding and Genomics, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
| | - Wisdom E K Agbeti
- Animal Breeding and Genomics, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
| | - Leo Kruijt
- Animal Breeding and Genomics, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
| | - Pauline Jéhannet
- Animal Breeding and Genomics, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
| | - Martin J Lankheet
- Experimental Zoology Group, Wageningen University & Research, 6700 AH Wageningen, The Netherlands
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Kadamani KL, Logan SM, Pamenter ME. Does hypometabolism constrain innate immune defense? Acta Physiol (Oxf) 2024; 240:e14091. [PMID: 38288574 DOI: 10.1111/apha.14091] [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: 01/08/2023] [Revised: 11/30/2023] [Accepted: 01/01/2024] [Indexed: 02/24/2024]
Abstract
Many animals routinely make energetic trade-offs to adjust to environmental demands and these trade-offs often have significant implications for survival. For example, environmental hypoxia is commonly experienced by many organisms and is an energetically challenging condition because reduced oxygen availability constrains aerobic energy production, which can be lethal. Many hypoxia-tolerant species downregulate metabolic demands when oxygen is limited; however, certain physiological functions are obligatory and must be maintained despite the need to conserve energy in hypoxia. Of particular interest is immunity (including both constitutive and induced immune functions) because mounting an immune response is among the most energetically expensive physiological processes but maintaining immune function is critical for survival in most environments. Intriguingly, physiological responses to hypoxia and pathogens share key molecular regulators such as hypoxia-inducible factor-1α, through which hypoxia can directly activate an immune response. This raises an interesting question: do hypoxia-tolerant species mount an immune response during periods of hypoxia-induced hypometabolism? Unfortunately, surprisingly few studies have examined interactions between immunity and hypometabolism in such species. Therefore, in this review, we consider mechanistic interactions between metabolism and immunity, as well as energetic trade-offs between these two systems, in hypoxia-tolerant animals but also in other models of hypometabolism, including neonates and hibernators. Specifically, we explore the hypothesis that such species have blunted immune responses in hypometabolic conditions and/or use alternative immune pathways when in a hypometabolic state. Evidence to date suggests that hypoxia-tolerant animals do maintain immunity in low oxygen conditions, but that the sensitivity of immune responses may be blunted.
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Affiliation(s)
- Karen L Kadamani
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Samantha M Logan
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, Ontario, Canada
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10
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Kell DB, Khan MA, Kane B, Lip GYH, Pretorius E. Possible Role of Fibrinaloid Microclots in Postural Orthostatic Tachycardia Syndrome (POTS): Focus on Long COVID. J Pers Med 2024; 14:170. [PMID: 38392604 PMCID: PMC10890060 DOI: 10.3390/jpm14020170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/16/2024] [Accepted: 01/27/2024] [Indexed: 02/24/2024] Open
Abstract
Postural orthostatic tachycardia syndrome (POTS) is a common accompaniment of a variety of chronic, inflammatory diseases, including long COVID, as are small, insoluble, 'fibrinaloid' microclots. We here develop the argument, with accompanying evidence, that fibrinaloid microclots, through their ability to block the flow of blood through microcapillaries and thus cause tissue hypoxia, are not simply correlated with but in fact, by preceding it, may be a chief intermediary cause of POTS, in which tachycardia is simply the body's exaggerated 'physiological' response to hypoxia. Similar reasoning accounts for the symptoms bundled under the term 'fatigue'. Amyloids are known to be membrane disruptors, and when their targets are nerve membranes, this can explain neurotoxicity and hence the autonomic nervous system dysfunction that contributes to POTS. Taken together as a system view, we indicate that fibrinaloid microclots can serve to link POTS and fatigue in long COVID in a manner that is at once both mechanistic and explanatory. This has clear implications for the treatment of such diseases.
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Affiliation(s)
- Douglas B. Kell
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK;
- The Novo Nordisk Foundation Centre for Biosustainability, Building 220, Chemitorvet 200, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch Private Bag X1, Matieland 7602, South Africa
| | - Muhammed Asad Khan
- Directorate of Respiratory Medicine, Manchester University Hospitals, Wythenshawe Hospital, Manchester M23 9LT, UK;
| | - Binita Kane
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK;
- Manchester University Foundation Trust and School of Biological Sciences, University of Manchester, Manchester M13 9PL, UK
| | - Gregory Y. H. Lip
- Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool L14 3PE, UK;
- Danish Center for Health Services Research, Department of Clinical Medicine, Aalborg University, 9220 Aalborg, Denmark
| | - Etheresia Pretorius
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK;
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch Private Bag X1, Matieland 7602, South Africa
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11
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Bothe TL, Gunga HC, Pilz N, Heinz V, Opatz OS. Relativistic aspects of physiology: Expanding our understanding of conventional control loops. Acta Physiol (Oxf) 2023; 239:e14064. [PMID: 37964669 DOI: 10.1111/apha.14064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/16/2023]
Affiliation(s)
- T L Bothe
- Institute of Physiology, Center for Space Medicine and Extreme Environments Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - H C Gunga
- Institute of Physiology, Center for Space Medicine and Extreme Environments Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - N Pilz
- Institute of Physiology, Center for Space Medicine and Extreme Environments Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Institute of Translational Physiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - V Heinz
- Institute of Physiology, Center for Space Medicine and Extreme Environments Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - O S Opatz
- Institute of Physiology, Center for Space Medicine and Extreme Environments Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
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12
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Liu J, Zhao Z, Li J, Zhang Q, Wang Y, Zhang J. Association between transcutaneous oxygen saturation within 24 h of admission and mortality in critically ill patients with non-traumatic subarachnoid hemorrhage: a retrospective analysis of the MIMIC-IV database. Front Neurol 2023; 14:1292260. [PMID: 38053796 PMCID: PMC10694199 DOI: 10.3389/fneur.2023.1292260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/30/2023] [Indexed: 12/07/2023] Open
Abstract
Background In critically ill patients, transcutaneous oxygen saturation (SpO2) upon admission is typically associated with in-hospital mortality. Nevertheless, the available information for patients with non-traumatic subarachnoid hemorrhage (SAH) is limited. In our study, our objective was to assess the correlation between SpO2 levels and mortality among patients diagnosed with severe SAH. Methods In this study, we extracted data from the Medical Information Marketplace in Intensive Care (MIMIC-IV) database, which comprises information on critically ill patients. By employing matching ICD-9 and ICD-10 codes, we identified 3,328 patients diagnosed with SAH. Every individual who was admitted to the intensive care unit (ICU) had their SpO2 data and various covariates, including age, sex, diagnosis, and duration of stay, recorded upon admission. Subsequently, the patients were categorized into three distinct groups according to their SpO2 levels: low (≤95%), moderate (95-98%), and high (≥98%). To investigate the association between percutaneous oxygen saturation and mortality in patients with severe SAH, logistic regression, and cubic spline models were utilized. The main outcomes of interest were 28- and 90-day mortality rates. Additionally, subgroup analyses were conducted to evaluate these correlations and assess the consistency of interactions. Results A cohort of 864 patients diagnosed with non-traumatic SAH was included in this study. The correlation between SpO2 and mortality displayed a U-shaped curve when utilizing a finite cubic spline function (non-linearity < 0.001), with the nadir in the probability of in-hospital death at 96%. Mortality at 28 and 90 days showed an inverse correlation with SpO2 < 96% (adjusted odds ratio [OR], 0.8; 95% confidence interval [CI], 0.67-0.95, and 0.76; 95% CI, 0.6-0.96). Conversely, there was a positive correlation between percutaneous oxygen saturation (SpO2) levels of ≥96% and mortality rates at both 28 and 90 days (adjusted OR, 1.17; 95% CI, 1.02-1.35 and 1.2; 95% CI, 1.05-1.39). Conclusion In patients with severe subarachnoid hemorrhage, the association between SpO2 and mortality at 28 and 90 days demonstrated a U-shaped pattern. When SpO2 levels were between 95 and 98%, both short- and long-term mortality rates were at their lowest. Patients with significant subarachnoid hemorrhage had a lower chance of survival when their SpO2 values were either high or low.
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Affiliation(s)
- Junjie Liu
- College of Clinical Medicine, North China University of Science and Technology, Tangshan, China
| | - Zongxu Zhao
- College of Stomatology, North China University of Science and Technology, Tangshan, China
| | - Jianmin Li
- Department of Neurosurgical Intensive Care Unit, The Affiliated Hospital, North China University of Science and Technology, Tangshan, China
| | - Qiuhua Zhang
- College of Clinical Medicine, North China University of Science and Technology, Tangshan, China
| | - Yichao Wang
- College of Clinical Medicine, North China University of Science and Technology, Tangshan, China
| | - Junwei Zhang
- Department of Neurosurgical Intensive Care Unit, The Affiliated Hospital, North China University of Science and Technology, Tangshan, China
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13
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Lear CA, Beacom MJ, Dhillon SK, Lear BA, Mills OJ, Gunning MI, Westgate JA, Bennet L, Gunn AJ. Dissecting the contributions of the peripheral chemoreflex and myocardial hypoxia to fetal heart rate decelerations in near-term fetal sheep. J Physiol 2023; 601:2017-2041. [PMID: 37017488 DOI: 10.1113/jp284286] [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: 12/19/2022] [Accepted: 03/30/2023] [Indexed: 04/06/2023] Open
Abstract
Brief repeated fetal hypoxaemia during labour can trigger intrapartum decelerations of the fetal heart rate (FHR) via the peripheral chemoreflex or the direct effects of myocardial hypoxia, but the relative contribution of these two mechanisms and how this balance changes with evolving fetal compromise remain unknown. In the present study, chronically instrumented near-term fetal sheep received surgical vagotomy (n = 8) or sham vagotomy (control, n = 11) to disable the peripheral chemoreflex and unmask myocardial hypoxia. One-minute complete umbilical cord occlusions (UCOs) were performed every 2.5 min for 4 h or until arterial pressure fell below 20 mmHg. Hypotension and severe acidaemia developed progressively after 65.7 ± 7.2 UCOs in control fetuses and 49.5 ± 7.8 UCOs after vagotomy. Vagotomy was associated with faster development of metabolic acidaemia and faster impairment of arterial pressure during UCOs without impairing centralization of blood flow or neurophysiological adaptation to UCOs. During the first half of the UCO series, before severe hypotension developed, vagotomy was associated with a marked increase in FHR during UCOs. After the onset of evolving severe hypotension, FHR fell faster in control fetuses during the first 20 s of UCOs, but FHR during the final 40 s of UCOs became progressively more similar between groups, with no difference in the nadir of decelerations. In conclusion, FHR decelerations were initiated and sustained by the peripheral chemoreflex at a time when fetuses were able to maintain arterial pressure. After the onset of evolving hypotension and acidaemia, the peripheral chemoreflex continued to initiate decelerations, but myocardial hypoxia became progressively more important in sustaining and deepening decelerations. KEY POINTS: Brief repeated hypoxaemia during labour can trigger fetal heart rate decelerations by either the peripheral chemoreflex or myocardial hypoxia, but how this balance changes with fetal compromise is unknown. Reflex control of fetal heart rate was disabled by vagotomy to unmask the effects of myocardial hypoxia in chronically instrumented fetal sheep. Fetuses were then subjected to repeated brief hypoxaemia consistent with the rates of uterine contractions during labour. We show that the peripheral chemoreflex controls brief decelerations in their entirety at a time when fetuses were able to maintain normal or increased arterial pressure. The peripheral chemoreflex still initiated decelerations even after the onset of evolving hypotension and acidaemia, but myocardial hypoxia made an increasing contribution to sustain and deepen decelerations.
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Affiliation(s)
- Christopher A Lear
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Michael J Beacom
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Simerdeep K Dhillon
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Benjamin A Lear
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Olivia J Mills
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Mark I Gunning
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Jenny A Westgate
- Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
- Department of Paediatrics, Starship Children's Hospital, Auckland, New Zealand
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14
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Cerra MC, Filice M, Caferro A, Mazza R, Gattuso A, Imbrogno S. Cardiac Hypoxia Tolerance in Fish: From Functional Responses to Cell Signals. Int J Mol Sci 2023; 24:ijms24021460. [PMID: 36674975 PMCID: PMC9866870 DOI: 10.3390/ijms24021460] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
Aquatic animals are increasingly challenged by O2 fluctuations as a result of global warming, as well as eutrophication processes. Teleost fish show important species-specific adaptability to O2 deprivation, moving from intolerance to a full tolerance of hypoxia and even anoxia. An example is provided by members of Cyprinidae which includes species that are amongst the most tolerant hypoxia/anoxia teleosts. Living at low water O2 requires the mandatory preservation of the cardiac function to support the metabolic and hemodynamic requirements of organ and tissues which sustain whole organism performance. A number of orchestrated events, from metabolism to behavior, converge to shape the heart response to the restricted availability of the gas, also limiting the potential damages for cells and tissues. In cyprinids, the heart is extraordinarily able to activate peculiar strategies of functional preservation. Accordingly, by using these teleosts as models of tolerance to low O2, we will synthesize and discuss literature data to describe the functional changes, and the major molecular events that allow the heart of these fish to sustain adaptability to O2 deprivation. By crossing the boundaries of basic research and environmental physiology, this information may be of interest also in a translational perspective, and in the context of conservative physiology, in which the output of the research is applicable to environmental management and decision making.
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15
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Yin H, Yang R, Xin Y, Jiang T, Zhong D. In-hospital mortality and SpO2 incritical care patients with cerebral injury: data from the MIMIC‑IV Database. BMC Anesthesiol 2022; 22:386. [PMID: 36510130 PMCID: PMC9743499 DOI: 10.1186/s12871-022-01933-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Evidence regarding the relationship between in-hospital mortality and SpO2 was low oxygen saturations are often thought to be harmful, new research in patients with brain damage has found that high oxygen saturation actually enhances mortality. However, there is currently no clear study to point out the appropriate range for oxygen saturation in patients with craniocerebral diseases. METHODS: By screening all patients in the MIMIC IV database, 3823 patients with craniocerebral diseases (according to ICD-9 codes and ICD-10) were selected, and non-linear regression was used to analyze the relationship between in-hospital mortality and oxygen saturation. Covariates for all patients included age, weight, diagnosis, duration of ICU stay, duration of oxygen therapy, etc. RESULTS: In-hospital mortality in patients with TBI and SAH was kept to a minimum when oxygen saturation was in the 94-96 range. And in all patients, the relationship between oxygen saturation and in-hospital mortality was U-shaped. Subgroup analysis of the relationship between oxygen saturation and mortality in patients with metabolic encephalopathy and other encephalopathy also draws similar conclusions In-hospital mortality and oxygen saturation were all U-shaped in patients with subarachnoid hemorrhage, metabolic and toxic encephalopathy, cerebral infarction, and other encephalopathy, but the nonlinear regression was statistically significant only in patients with cerebral infarction (p for nonlinearity = 0.002). CONCLUSION Focusing too much on the lower limit of oxygen saturation and ignoring too high oxygen saturation can also lead to increase in-hospital mortality. For patients with TBI and SAH, maintaining oxygen saturation at 94-96% will minimize the in-hospital mortality of patients.
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Affiliation(s)
- Haoyang Yin
- grid.452206.70000 0004 1758 417XDepartment of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Rui Yang
- grid.452206.70000 0004 1758 417XDepartment of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yun Xin
- grid.452206.70000 0004 1758 417XDepartment of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Tao Jiang
- grid.452206.70000 0004 1758 417XDepartment of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Dong Zhong
- grid.452206.70000 0004 1758 417XDepartment of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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16
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Stöhr EJ. The healthy heart does not control a specific cardiac output: a plea for a new interpretation of normal cardiac function. Am J Physiol Heart Circ Physiol 2022; 323:H1239-H1243. [PMID: 36269649 DOI: 10.1152/ajpheart.00535.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The current evidence suggests that the healthy heart does not sense the optimal cardiac output (Q̇) because the different organ systems that influence cardiac function do not interact to adjust their individual responses toward a specific Q̇. Consequently, it is conceivable that the complex cycle of cardiac contraction and relaxation must occur for reasons other than to produce a specific target Q̇ and that there is likely a yet undiscovered overarching principle in the cardiovascular system that explains the combined effects of the prevailing preload, afterload, and contractility. Future research should embrace the possibility of a different purpose to cardiac function than previously assumed and examine the biological capacity of this fascinating organ accordingly.
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Affiliation(s)
- Eric J Stöhr
- COR-HELIX (CardiOvascular Regulation and Human Exercise Laboratory - Integration and Xploration), Leibniz University Hannover, Hannover, Germany
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17
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Joyce W, Pan YK, Garvey K, Saxena V, Perry S. Regulation of heart rate following genetic deletion of the ß1 adrenergic receptor in larval zebrafish. Acta Physiol (Oxf) 2022; 235:e13849. [PMID: 35665450 PMCID: PMC9539580 DOI: 10.1111/apha.13849] [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: 04/20/2022] [Revised: 05/17/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022]
Abstract
Aim Although zebrafish are gaining popularity as biomedical models of cardiovascular disease, our understanding of their cardiac control mechanisms is fragmentary. Our goal was to clarify the controversial role of the ß1‐adrenergic receptor (AR) in the regulation of heart rate in zebrafish. Methods CRISPR‐Cas9 was used to delete the adrb1 gene in zebrafish allowing us to generate a stable adrb1−/− line. Larval heart rates were measured during pharmacological protocols and with exposure to hypercapnia. Expression of the five zebrafish adrb genes were measured in larval zebrafish hearts using qPCR. Results Compared with genetically matched wild‐types (adrb1+/+), adrb1−/− larvae exhibited ~20 beats min−1 lower heart rate, measured from 2 to 21 days post‐fertilization (dpf). Nevertheless, adrb1−/− larvae exhibited preserved positive chronotropic responses to pharmacological treatment with AR agonists (adrenaline, noradrenaline, isoproterenol), which were blocked by propranolol (general ß‐AR antagonist). Regardless of genotype, larvae exhibited similar increases in heart rate in response to hypercapnia (1% CO2) at 5 dpf, but tachycardia was blunted in adrb1−/− larvae at 6 dpf. adrb1 gene expression was abolished in the hearts of adrb1−/− larvae, confirming successful knockout. While gene expression of adrb2a and adrb3a was unchanged, adrb2b and adrb3b mRNA levels increased in adrb1−/− larval hearts. Conclusion Despite adrb1 contributing to the setting of resting heart rate in larvae, it is not strictly essential for zebrafish, as we generated a viable and breeding adrb1−/− line. The chronotropic effects of adrenergic stimulation persist in adrb1−/− zebrafish, likely due to the upregulation of other ß‐AR subtypes.
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Affiliation(s)
- William Joyce
- Department of Biology University of Ottawa Ottawa Ontario Canada
- Department of Biology – Zoophysiology Aarhus Universitet Aarhus C Denmark
| | - Yihang K. Pan
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Kayla Garvey
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Vishal Saxena
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Steve F. Perry
- Department of Biology University of Ottawa Ottawa Ontario Canada
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