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Lafuente JV, Sharma A, Feng L, Muresanu DF, Nozari A, Tian ZR, Buzoianu AD, Sjöquist PO, Wiklund L, Sharma HS. Nanowired Delivery of Mesenchymal Stem Cells with Antioxidant Compound H-290/51 Reduces Exacerbation of Methamphetamine Neurotoxicity in Hot Environment. ADVANCES IN NEUROBIOLOGY 2023; 32:317-352. [PMID: 37480465 DOI: 10.1007/978-3-031-32997-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Military personnel are often exposed to hot environments either for combat operations or peacekeeping missions. Hot environment is a severe stressful situation leading to profound hyperthermia, fatigue and neurological impairments. To avoid stressful environment, some people frequently use methamphetamine (METH) or other psychostimulants to feel comfortable under adverse situations. Our studies show that heat stress alone induces breakdown of the blood-brain barrier (BBB) and edema formation associated with reduced cerebral blood flow (CBF). On the other hand, METH alone induces hyperthermia and neurotoxicity. These effects of METH are exacerbated at high ambient temperatures as seen with greater breakdown of the BBB and brain pathology. Thus, a combination of METH use at hot environment may further enhance the brain damage-associated behavioral dysfunctions. METH is well known to induce severe oxidative stress leading to brain pathology. In this investigation, METH intoxication at hot environment was examined on brain pathology and to explore suitable strategies to induce neuroprotection. Accordingly, TiO2-nanowired delivery of H-290/51 (150 mg/kg, i.p.), a potent chain-breaking antioxidant in combination with mesenchymal stem cells (MSCs), is investigated in attenuating METH-induced brain damage at hot environment in model experiments. Our results show that nanodelivery of H-290/51 with MSCs significantly enhanced CBF and reduced BBB breakdown, edema formation and brain pathology following METH exposure at hot environment. These observations are the first to point out that METH exacerbated brain pathology at hot environment probably due to enhanced oxidative stress, and MSCs attenuate these adverse effects, not reported earlier.
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Affiliation(s)
- José Vicente Lafuente
- LaNCE, Department Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Lianyuan Feng
- Department of Neurology, Bethune International Peace Hospital, Zhongshan, Hebei Province, China
| | - Dafin F Muresanu
- Department Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania
- "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Ala Nozari
- Anesthesiology & Intensive Care, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA, USA
| | - Z Ryan Tian
- Department Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, USA
| | - Anca D Buzoianu
- Department of Clinical Pharmacology and Toxicology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Per-Ove Sjöquist
- Division of Cardiology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
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Li L, Hu D, Zhang W, Cui L, Jia X, Yang D, Liu S, Deng F, Liu J, Guo X. Effect of short-term exposure to particulate air pollution on heart rate variability in normal-weight and obese adults. Environ Health 2021; 20:29. [PMID: 33726760 PMCID: PMC7968215 DOI: 10.1186/s12940-021-00707-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/24/2021] [Indexed: 05/16/2023]
Abstract
BACKGROUND The adverse effects of particulate air pollution on heart rate variability (HRV) have been reported. However, it remains unclear whether they differ by the weight status as well as between wake and sleep. METHODS A repeated-measure study was conducted in 97 young adults in Beijing, China, and they were classified by body mass index (BMI) as normal-weight (BMI, 18.5-24.0 kg/m2) and obese (BMI ≥ 28.0 kg/m2) groups. Personal exposures to fine particulate matter (PM2.5) and black carbon (BC) were measured with portable exposure monitors, and the ambient PM2.5/BC concentrations were obtained from the fixed monitoring sites near the subjects' residences. HRV and heart rate (HR) were monitored by 24-h Holter electrocardiography. The study period was divided into waking and sleeping hours according to time-activity diaries. Linear mixed-effects models were used to investigate the effects of PM2.5/BC on HRV and HR in both groups during wake and sleep. RESULTS The effects of short-term exposure to PM2.5/BC on HRV were more pronounced among obese participants. In the normal-weight group, the positive association between personal PM2.5/BC exposure and high-frequency power (HF) as well as the ratio of low-frequency power to high-frequency power (LF/HF) was observed during wakefulness. In the obese group, personal PM2.5/BC exposure was negatively associated with HF but positively associated with LF/HF during wakefulness, whereas it was negatively correlated to total power and standard deviation of all NN intervals (SDNN) during sleep. An interquartile range (IQR) increase in BC at 2-h moving average was associated with 37.64% (95% confidence interval [CI]: 25.03, 51.51%) increases in LF/HF during wakefulness and associated with 6.28% (95% CI: - 17.26, 6.15%) decreases in SDNN during sleep in obese individuals, and the interaction terms between BC and obesity in LF/HF and SDNN were both statistically significant (p < 0.05). The results also suggested that the effects of PM2.5/BC exposure on several HRV indices and HR differed in magnitude or direction between wake and sleep. CONCLUSIONS Short-term exposure to PM2.5/BC is associated with HRV and HR, especially in obese individuals. The circadian rhythm of HRV should be considered in future studies when HRV is applied.
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Affiliation(s)
- Luyi Li
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Dayu Hu
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Wenlou Zhang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Liyan Cui
- Department of Laboratory Medicine, Peking University Third Hospital, Beijing, 100191, China
| | - Xu Jia
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Di Yang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Shan Liu
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
| | - Furong Deng
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China.
| | - Junxiu Liu
- Department of Otolaryngology Head and Neck Surgery, Peking University Third Hospital, Beijing, 100191, China.
| | - Xinbiao Guo
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, 100191, China
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Siebenmann C, Rasmussen P, Hug M, Keiser S, Flück D, Fisher JP, Hilty MP, Maggiorini M, Lundby C. Parasympathetic withdrawal increases heart rate after 2 weeks at 3454 m altitude. J Physiol 2017; 595:1619-1626. [PMID: 27966225 DOI: 10.1113/jp273726] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/21/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Heart rate is increased in chronic hypoxia and we tested whether this is the result of increased sympathetic nervous activity, reduced parasympathetic nervous activity, or a non-autonomic mechanism. In seven lowlanders, heart rate was measured at sea level and after 2 weeks at high altitude after individual and combined pharmacological inhibition of sympathetic and/or parasympathetic control of the heart. Inhibition of parasympathetic control of the heart alone or in combination with inhibition of sympathetic control abolished the high altitude-induced increase in heart rate. Inhibition of sympathetic control of the heart alone did not prevent the high altitude-induced increase in heart rate. These results indicate that a reduced parasympathetic nervous activity is the main mechanism underlying the elevated heart rate in chronic hypoxia. ABSTRACT Chronic hypoxia increases resting heart rate (HR), but the underlying mechanism remains incompletely understood. We investigated the relative contributions of the sympathetic and parasympathetic nervous systems, along with potential non-autonomic mechanisms, by individual and combined pharmacological inhibition of muscarinic and/or β-adrenergic receptors. In seven healthy lowlanders, resting HR was determined at sea level (SL) and after 15-18 days of exposure to 3454 m high altitude (HA) without drug intervention (control, CONT) as well as after intravenous administration of either propranolol (PROP), or glycopyrrolate (GLYC), or PROP and GLYC in combination (PROP+GLYC). Circulating noradrenaline concentration increased from 0.9 ± 0.4 nmol l-1 at SL to 2.7 ± 1.5 nmol l-1 at HA (P = 0.03). The effect of HA on HR depended on the type of autonomic inhibition (P = 0.006). Specifically, HR was increased at HA from 64 ± 10 to 74 ± 12 beats min-1 during the CONT treatment (P = 0.007) and from 52 ± 4 to 59 ± 5 beats min-1 during the PROP treatment (P < 0.001). In contrast, HR was similar between SL and HA during the GLYC treatment (110 ± 7 and 112 ± 5 beats min-1 , P = 0.28) and PROP+GLYC treatment (83 ± 5 and 85 ± 5 beats min-1 , P = 0.25). Our results identify a reduction in cardiac parasympathetic activity as the primary mechanism underlying the elevated HR associated with 2 weeks of exposure to hypoxia. Unexpectedly, the sympathoactivation at HA that was evidenced by increased circulating noradrenaline concentration had little effect on HR, potentially reflecting down-regulation of cardiac β-adrenergic receptor function in chronic hypoxia. These effects of chronic hypoxia on autonomic control of the heart may concern not only HA dwellers, but also patients with disorders that are associated with hypoxaemia.
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Affiliation(s)
- Christoph Siebenmann
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.,Department of Environmental Physiology, School of Technology and Health, Royal Institute of Technology, Solna, Sweden
| | - Peter Rasmussen
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.,H. Lundbeck A/S, Valby, Denmark
| | - Mike Hug
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Stefanie Keiser
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Daniela Flück
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - James P Fisher
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Matthias P Hilty
- Intensive Care Unit, University Hospital of Zürich, Zürich, Switzerland
| | - Marco Maggiorini
- Intensive Care Unit, University Hospital of Zürich, Zürich, Switzerland
| | - Carsten Lundby
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
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Siebenmann C, Lundby C. Regulation of cardiac output in hypoxia. Scand J Med Sci Sports 2015; 25 Suppl 4:53-9. [DOI: 10.1111/sms.12619] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2015] [Indexed: 10/22/2022]
Affiliation(s)
- Christoph Siebenmann
- Department of Environmental Physiology; School of Technology and Health; Royal Institute of Technology; Solna Sweden
| | - Carsten Lundby
- Center for Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
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Etheredge C, Judge LW, Bellar DM. The effects of a personal oxygen supplement on performance, recovery, and cognitive function during and after exhaustive exercise. J Strength Cond Res 2014; 28:1255-62. [PMID: 24552803 DOI: 10.1519/jsc.0000000000000371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this investigation was to examine the effects of a personal oxygen supplement (OS) on performance during exhaustive exercise, respiratory responses during exhaustive exercise, and cognitive function after exhaustive exercise. The participants for this blind placebo-controlled experiment were apparently healthy college-aged adults (n = 20). First, VO2max was assessed (47.6 ± 9.8 ml O2·kg(-1)·min(-1)). Participants then ran 2 trials at 80% of VO2max speed to exhaustion and received either a placebo (compressed air) or personal OS. Psychomotor vigilance testing (PVT) was performed before and after each trial. Performance between treatments was evaluated through repeated measures analysis of variance (ANOVA) and was not found to be different (p = 0.335, ηp2 = 0.052), and order (placebo first or personal OS first) was not significant within the model (p = 0.305, ηp2 = 0.058). Mean times were 1,057.6 ± 619.8 seconds for the oxygen trials and 992.5 ± 463.1 seconds for the placebo trials. Repeated measures ANOVAs were used to assess minute ventilation (Ve, L·min(-1)) and VCO2 (L·O2·min(-1)) during exercise and recovery, mean heart rate during recovery, and PVT results. Treatment was nonsignificant (p > 0.05) nor were any interaction effects (treatment × time, p > 0.05) for any variables. The results of this study suggest that a personal OS had no effect on performance and did not affect ventilation even at the time directly surrounding the application. The results of the study also suggest that personal OS do not enhance exercise recovery or cognition during exercise recovery.
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Affiliation(s)
- Cory Etheredge
- 1School of Kinesiology, University of Louisiana, Lafayette, Louisiana; and 2School of Physical Education, Sport, and Exercise Science, Ball State University, Muncie, Indiana
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Cui F, Gao L, Yuan F, Dong ZF, Zhou ZN, Kline DD, Zhang Y, Li DP. Hypobaric intermittent hypoxia attenuates hypoxia-induced depressor response. PLoS One 2012; 7:e41656. [PMID: 22848558 PMCID: PMC3407201 DOI: 10.1371/journal.pone.0041656] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 06/25/2012] [Indexed: 11/17/2022] Open
Abstract
Background Hypobaric intermittent hypoxia (HIH) produces many favorable effects in the cardiovascular system such as anti-hypertensive effect. In this study, we showed that HIH significantly attenuated a depressor response induced by acute hypoxia. Methodology/Principal Findings Sprague-Dawley rats received HIH in a hypobaric chamber simulating an altitude of 5000 m. The artery blood pressure (ABP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded in anesthetized control rats and rats received HIH. The baseline ABP, HR and RSNA were not different between HIH and control rats. Acute hypoxia-induced decrease in ABP was significantly attenuated in HIH rat compared with control rats. However, acute hypoxia-induced increases in HR and RSNA were greater in HIH rat than in control rats. After removal of bilateral ascending depressor nerves, acute hypoxia-induced depressor and sympathoexcitatory responses were comparable in control and HIH rats. Furthermore, acute hypoxia-induced depressor and sympathoexcitatory responses did not differ between control and HIH groups after blocking ATP-dependent K+ channels by glibenclamide. The baroreflex function evaluated by intravenous injection of phenylephrine and sodium nitroprusside was markedly augmented in HIH rats compared with control rats. The pressor and sympathoexcitatory responses evoked by intravenous injection of cyanide potassium were also significantly greater in HIH rats than in control rats. Conclusions/Significance Our findings suggest that HIH suppresses acute hypoxia-induced depressor response through enhancement of baroreflex and chemoreflex function, which involves activation of ATP-dependent K+ channels. This study provides new information and underlying mechanism on the beneficiary effect of HIH on maintaining cardiovascular homeostasis.
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Affiliation(s)
- Fang Cui
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
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Berger MM, Luks AM, Bailey DM, Menold E, Robotti GC, Mairbäurl H, Dehnert C, Swenson ER, Bärtsch P. Transpulmonary Plasma Catecholamines in Acute High-Altitude Pulmonary Hypertension. Wilderness Environ Med 2011; 22:37-45. [DOI: 10.1016/j.wem.2010.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Revised: 10/30/2010] [Accepted: 11/19/2010] [Indexed: 11/16/2022]
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Abstract
Aerobic exercise capacity decreases with exposure to hypoxia. This article focuses on the effects of hypoxia on nervous system function and the potential consequences for the exercising human. Emphasis is put on somatosensory muscle afferents due to their crucial role in the reflex inhibition of muscle activation and in cardiorespiratory reflex control during exercise. We review the evidence of hypoxia influences on muscle afferents and discuss important consequences for exercise performance. Efferent (motor) nerves are less affected at altitude and are thought to stay fairly functional even in severe levels of arterial hypoxemia. Altitude also alters autonomic nervous system functions, which are thought to play an important role in the regulation of cardiac output and ventilation. Finally, the consequences of hypoxia-induced cortical adaptations and dysfunctions are evaluated in terms of neurotransmitter turnover, brain electrical activity, and cortical excitability. Even though the cessation of exercise or the reduction of exercise intensity, when reaching maximum performance, implies reduced motor recruitment by the nervous system, the mechanisms that lead to the de-recruitment of active muscle are still not well understood. In moderate hypoxia, muscle afferents appear to play an important role, whereas in severe hypoxia brain oxygenation may play a more important role.
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Affiliation(s)
- Markus Amann
- University of Zürich , Institute of Physiology, and ETH Zürich, Exercise Physiology, Zürich, Switzerland.
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Effects of hypoxia on blood pressure regulation: interval hypoxic training as compared to obstructive sleep apnea – the other side of the coin? J Hypertens 2009; 27:1527-32. [DOI: 10.1097/hjh.0b013e3283300d6d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Serebrovskaya TV, Manukhina EB, Smith ML, Downey HF, Mallet RT. Intermittent hypoxia: cause of or therapy for systemic hypertension? Exp Biol Med (Maywood) 2008; 233:627-50. [PMID: 18408145 DOI: 10.3181/0710-mr-267] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
During acute episodes of hypoxia, chemoreceptor-mediated sympathetic activity increases heart rate, cardiac output, peripheral resistance and systemic arterial pressure. However, different intermittent hypoxia paradigms produce remarkably divergent effects on systemic arterial pressure in the post-hypoxic steady state. The hypertensive effects of obstructive sleep apnea (OSA) vs. the depressor effects of therapeutic hypoxia exemplify this divergence. OSA, a condition afflicting 15-25% of American men and 5-10% of women, has been implicated in the pathogenesis of systemic hypertension and is a major risk factor for heart disease and stroke. OSA imposes a series of brief, intense episodes of hypoxia and hypercapnia, leading to persistent, maladaptive chemoreflex-mediated activation of the sympathetic nervous system which culminates in hypertension. Conversely, extensive evidence in animals and humans has shown controlled intermittent hypoxia conditioning programs to be safe, efficacious modalities for prevention and treatment of hypertension. This article reviews the pertinent literature in an attempt to reconcile the divergent effects of intermittent hypoxia therapy and obstructive sleep apnea on hypertension. Special emphasis is placed on research conducted in the nations of the former Soviet Union, where intermittent hypoxia conditioning programs are being applied therapeutically to treat hypertension in patients. Also reviewed is evidence regarding mechanisms of the pro- and anti-hypertensive effects of intermittent hypoxia.
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Barnholt KE, Hoffman AR, Rock PB, Muza SR, Fulco CS, Braun B, Holloway L, Mazzeo RS, Cymerman A, Friedlander AL. Endocrine responses to acute and chronic high-altitude exposure (4,300 meters): modulating effects of caloric restriction. Am J Physiol Endocrinol Metab 2006; 290:E1078-88. [PMID: 16380390 DOI: 10.1152/ajpendo.00449.2005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-altitude anorexia leads to a hormonal response pattern modulated by both hypoxia and caloric restriction (CR). The purpose of this study was to compare altitude-induced neuroendocrine changes with or without energy imbalance and to explore how energy sufficiency alters the endocrine acclimatization process. Twenty-six normal-weight, young men were studied for 3 wk. One group [hypocaloric group (HYPO), n = 9] stayed at sea level and consumed 40% fewer calories than required to maintain body weight. Two other groups were deployed to 4,300 meters (Pikes Peak, CO), where one group (ADQ, n = 7) was adequately fed to maintain body weight and the other [deficient group (DEF), n = 10] had calories restricted as above. HYPO experienced a typical CR-induced reduction in many hormones such as insulin, testosterone, and leptin. At altitude, fasting glucose, insulin, and epinephrine exhibited a muted rise in DEF compared with ADQ. Free thyroxine, thyroid-stimulating hormone, and norepinephrine showed similar patterns between the two altitude groups. Morning cortisol initially rose higher in DEF than ADQ at 4,300 meters, but the difference disappeared by day 5. Testosterone increased in both altitude groups acutely but declined over time in DEF only. Adiponectin and leptin did not change significantly from sea level baseline values in either altitude group regardless of energy intake. These data suggest that hypoxia tends to increase blood hormone concentrations, but anorexia suppresses elements of the endocrine response. Such suppression results in the preservation of energy stores but may sacrifice the facilitation of oxygen delivery and the use of oxygen-efficient fuels.
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Affiliation(s)
- Kimberly E Barnholt
- Clinical Studies Unit, VA Palo Alto Health Care System, 3801 Miranda Ave., Palo Alto, CA 94304, USA
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Kawaguchi T, Tsubone H, Hori M, Ozaki H, Kuwahara M. Cardiovascular and autonomic nervous functions during acclimatization to hypoxia in conscious rats. Auton Neurosci 2005; 117:97-104. [PMID: 15664562 DOI: 10.1016/j.autneu.2004.11.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Revised: 11/19/2004] [Accepted: 11/23/2004] [Indexed: 11/28/2022]
Abstract
The time courses of changes in cardiovascular and autonomic nervous functions during acclimatization to hypoxia were studied in conscious Sprague-Dawley rats. The animals were kept under a 12:12-h light-dark cycle and exposed to hypoxia (1 atm, 10% O2). Implanted telemetry transmitters were used to record blood pressure (BP). Changes in heart rate (HR) and BP were monitored over a 21-day period, and variations before and during hypoxia were analyzed using the wavelet transform method. The HR, high-frequency power of HR variability (HR-HF) and low-frequency power of BP variability (BP-LF) were all significantly increased after 1 h of hypoxia, whereas the LF/HF ratio of HR variability did not change. After this initial increase, both HR and the BP-LF were found to decrease. On the first day of hypoxia, HR and BP-LF values were significantly lower than those of the control rats, whereas the HR-HF was higher. Subsequently, these values altered so that they were similar to the control after 14 days of hypoxia. In addition, the amplitude of diurnal variation in HR was reduced during hypoxia. These results suggest that a sequence of dynamic interactions between sympathetic and parasympathetic nervous activities might have important roles in the regulation of cardiovascular function during acclimatization to hypoxia.
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Affiliation(s)
- Tomohiro Kawaguchi
- Department of Comparative Pathophysiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Pavan P, Sarto P, Merlo L, Casara D, Ponchia A, Biasin R, Noventa D, Avogaro A. Metabolic and Cardiovascular Parameters in Type 1 Diabetes at Extreme Altitude. Med Sci Sports Exerc 2004; 36:1283-9. [PMID: 15292733 DOI: 10.1249/01.mss.0000135782.93008.6c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The American Diabetes Association states that physical activity can be performed by individuals with Type 1 diabetes. Nevertheless, extreme altitude mountaineering represents a demanding challenge. We present the metabolic and cardiovascular parameters found in individuals with Type 1 diabetes during the ascent to Cho Oyu located at a height of 8201 m. METHODS Six individuals with Type 1 diabetes and 10 matched controls participated in the expedition. Both groups were evaluated before and after 4 h of trekking for vital indices, blood gases, acute mountain sickness, and metabolic control at 0, 3700, and 5800 m. RESULTS No difference between the groups was observed in acute mountain sickness scores. There was a progressive elevation in basal heart rates in both groups at increasing altitude while no changes were observed in mean blood pressures. After the 3 h of trekking, a significant increase in heart rate was observed in the controls at 0 m whereas a significant decrease in blood pressure was observed at higher altitude only in controls. HbA1c levels were worse after the expedition in both groups. A progressive increase in insulin requirement was observed in subjects with Type 1 diabetes (38 +/- 6 U x d(-1) at 0 m to 51 +/- 6 at 4200 m, P < 0.001). At an altitude of 5800 m, there was a significant increase in blood lactate concentration, independently of the activity level in the two groups. CONCLUSIONS At extreme altitude, highly motivated trekkers with Type 1 diabetes but free from long-term complications present metabolic and cardiovascular parameters comparable with those of control subjects despite a worsening in metabolic control. This type of physical activity must be accompanied by careful glucose monitoring.
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Affiliation(s)
- Paola Pavan
- Division of Metabolic Diseases, University Hospital, University of Padova, Italy
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