Experimental Physiology最新文献

{"title":"Sex differences in loop gain measured via superimposed end-expiratory breath holds and inspired steady-state hypoxia.","authors":"Benjamin W L MacKenzie, Nicole A Johnson, Nicholas D J Strzalkowski, Trevor A Day","doi":"10.1113/EP092285","DOIUrl":"https://doi.org/10.1113/EP092285","url":null,"abstract":"<p><p>Acute low oxygen exposure (hypoxia) elicits a hypoxic ventilatory response (HVR), which increases ventilation and mitigates hypoxaemia. During sustained exposure to hypoxia, ventilatory acclimatization increases peripheral chemoreflex (HVR) sensitivity or chemoreflex loop gain (LG). Although increased ventilation protects oxygenation, increased LG contributes to ventilatory instability during sleep (central sleep apnoea; CSA). The HVR is highly variable between individuals, and the impact of sex on HVR variability and LG is unclear. At low altitude (1100 m), we aimed to characterize a novel breath hold method to quantify LG using a standardized series of short (∼10 s), voluntary, end-expiratory breath holds (EEBH), using a background of steady-state normobaric inspired hyperoxia (fraction of inspired oxygen; <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${F_{{mathrm{I}}{{mathrm{O}}_2}}}$</annotation></semantics> </math>  = 1.0), normoxia (i.e., ambient air; <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${F_{{mathrm{I}}{{mathrm{O}}_2}}}$</annotation></semantics> </math>  = 0.21) and hypoxia ( <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${F_{{mathrm{I}}{{mathrm{O}}_2}}}$</annotation></semantics> </math>  = 0.14; equivalent to ∼4300 m altitude). Further, we investigated sex differences in LG during differential oxygen exposure using this novel EEBH protocol to quantify LG. We hypothesized that (a) LG magnitude would follow an inverse oxygen-dependent pattern with each inspired gas condition, and (b) that males would have higher LG than females. We recruited 36 healthy participants (18 females; 18 males). We found (a) a graded, inverse oxygen-dependent effect on LG magnitude (P < 0.0001), and (b) a sex-specific effect, whereby males had significantly larger LG magnitudes than females, but only in steady-state inspired hypoxia (P < 0.032). Our EEBH protocol illustrates an intrinsic sex difference in chemoreflex LG in hypoxia, which may underlie known sex differences in CSA at high altitude and in heart failure populations.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144729013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sweat evaporation in humans: A molecular and thermodynamic perspective.","authors":"Edward T Ashworth","doi":"10.1113/EP093011","DOIUrl":"https://doi.org/10.1113/EP093011","url":null,"abstract":"<p><p>Evaporative heat loss through sweating is essential for maintaining thermal balance in humans, particularly during exercise or in hot environments. Although the physiological mechanisms regulating sweat production and skin blood flow are well documented, the molecular processes underpinning sweat evaporation are less often considered. This review explores the physics of sweat evaporation from first principles, examining how energy is transferred, how water molecules escape the liquid phase and how this process is shaped by local and systemic factors. At the molecular level, evaporation occurs when surface water molecules attain sufficient kinetic energy to overcome hydrogen bonding. The energy required for this phase change, the latent heat of vaporisation, is supplied via conduction from the skin and, ultimately, from core body heat. The molecular energy within the sweat layer follows a Boltzmann distribution, meaning that only a subset of molecules have sufficient energy to evaporate at any time. As these high-energy molecules escape, the remaining sweat cools, helping to lower body temperature. This process continues as long as heat is resupplied via skin blood flow. Environmental conditions, such as humidity, airflow and clothing, affect the likelihood that evaporated molecules will remain in the vapour phase, while electrolytes in sweat can slightly reduce vapour pressure by locally altering the bonding structure of water. These factors determine how effectively sweat can evaporate by influencing surface area and liquid retention. By linking classical thermodynamics to human physiology, this review presents a unified framework for understanding how molecular interactions, statistical physics and environmental conditions converge to influence heat loss.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144729014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental physiology Special Issue: ‘Mechanotransduction, muscle spindles and proprioception’","authors":"Stephan Kröger","doi":"10.1113/EP093067","DOIUrl":"10.1113/EP093067","url":null,"abstract":"&lt;p&gt;This Special Issue of &lt;i&gt;Experimental Physiology&lt;/i&gt; contains a collection of 11 exquisite articles most of which are based on oral presentations presented at the second meeting on ‘Mechanotransduction, Muscle Spindles and Proprioception’, which took place in the halls of the Siemens Foundation in Munich in July 2024. The participants included more than 30 speakers from Taiwan, Canada, Australia, the United States and Israel as well as from all over Europe and the UK (Figure 1). Many of the speakers had already presented in the first, &amp; meeting on this topic in Munich in 2022 (Kröger, &lt;span&gt;2024&lt;/span&gt;). In this Editorial I would like to first briefly introduce the topic of the meeting before putting the individual articles into perspective.&lt;/p&gt;&lt;p&gt;The activity of almost every muscle is accompanied by sensory feedback informing the brain about the speed, direction and force of the movement. The interpretation of this information by the central nervous system (CNS) generates our sense of proprioception, which is essential for the execution of every voluntary movement, for perceiving the position of our body and limbs in relationship to one another and to our surroundings, and for posture and dexterity (Proske &amp; Gandevia, &lt;span&gt;2012&lt;/span&gt;). However, proprioception has many more functions, including, for example, the alignment of the spine (Blecher et al., &lt;span&gt;2017&lt;/span&gt;) and healing of fractured bones (Blecher et al., &lt;span&gt;2017&lt;/span&gt;). The responsiveness of our proprioceptive information is also subject to cognitive and emotional factors (Ackerley et al., &lt;span&gt;2017&lt;/span&gt;). Moreover, proprioceptive information endows us with a sense of self-awareness – an important aspect particularly for amputees. Correspondingly, dexterity and the rejection rate are significantly improved in amputees if the prosthesis is equipped with devices that provide sensory feedback equivalent to proprioceptive information (Raspopovic et al., &lt;span&gt;2021&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;Although proprioception is an accomplishment of an integrative system which processes information from a combination of peripheral sensory inputs including muscle length and tension, joint angle, and skin stretch (Macefield &amp; Knellwolf, &lt;span&gt;2018&lt;/span&gt;), by far the most influential components are muscle spindles (Matthews, &lt;span&gt;2015&lt;/span&gt;). Embedded in almost every skeletal muscle, these primary proprioceptive sensory organs constantly relay information about muscle tone and length to the thalamus and then via the dorsal (posterior) column–medial lemniscal system to the CNS (Kröger &amp; Watkins, &lt;span&gt;2021&lt;/span&gt;; Marasco &amp; de Nooij, &lt;span&gt;2023&lt;/span&gt;; Proske &amp; Gandevia, &lt;span&gt;2012&lt;/span&gt;). The processing and integration of this information in the CNS allows the precise determination of the spatial position and motion of the body and limbs in space, a process crucial for motor control, voluntary movement, posture and a stable gait. Moreover, the human body can initiate correct","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":"110 10","pages":"1383-1388"},"PeriodicalIF":2.8,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://physoc.onlinelibrary.wiley.com/doi/epdf/10.1113/EP093067","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144717800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carotid artery dissection linked to intermittent apnoeic swimming: A case-control study.","authors":"Damian M Bailey, Richard G Davies, Brenig L Gwilym, Benjamin S Stacey, Danny Walmsley, Michael H Lewis, Josip Butkovic, Ivan Mumlek, Brad Perry, Zvonomir Vrselja, Shigehiko Ogoh, James A Pawelczyk, Mohamad Bashir, Richard D White, Ian M Williams","doi":"10.1113/EP093047","DOIUrl":"https://doi.org/10.1113/EP093047","url":null,"abstract":"<p><p>Internal carotid artery (ICA) dissection is a rare and potentially devastating cause of cerebral ischaemia, initiated by an intimal tear or rupture of the vasa vasorum, that can lead to an intraluminal thrombus, vascular stenosis, occlusion, or dissecting aneurysm formation. Management is challenging due to its complex pathophysiology and non-specific nature of symptoms. In this case-control study, we were able to document the clinical presentation and management of an ICA dissection in a hypertensive, 50-year-old male triathlete following an acute bout of intermittent apnoeic (pyramid breathing) swimming. He developed blurred vision in his left eye, ipsilateral headache, pulsatile tinnitus and later noticed left-sided ptosis and pupil miosis consistent with Horner's syndrome, prompting specialist referral. Neuroimaging confirmed a dissection of the left ICA and incidental pseudoaneurysm of the distal right ICA. The patient recovered well due to a combination of pharmacological/dietary management of hypertension and graduated, structured return to physical activity and competition, culminating in significant re-expansion of the ICA true lumen calibre. We also conducted a laboratory-based, dry-land, static swimming simulation in an age- and physical activity-matched healthy male control. This demonstrated that exercise-induced ICA shear stress was more exaggerated during dynamic apnoeic breathing compared to normal breathing, which, in the setting of the patient's hypertension, may have been a precipitating factor underlying ICA dissection. Collectively, these findings provide unique insights into the pathophysiology and management of this rare condition while highlighting the inherent risks associated with this mode of exercise training in susceptible individuals with hypertension.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144717799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of short-term consumption of a Western diet on aerobic exercise performance in bank voles with inherently distinct metabolic rates.","authors":"Alaa Hseiky, Edyta T Sadowska, Paweł Koteja","doi":"10.1113/EP092646","DOIUrl":"https://doi.org/10.1113/EP092646","url":null,"abstract":"<p><p>Because obesity and related diseases are partly attributed to unrestricted consumption of a high-fat, high-sugar Western diet (WD), several studies have examined its adverse effects on health and physical fitness. However, short-term WD supplementation has received little attention. We asked whether such supplementation can improve the aerobic exercise performance of animals with inherently distinct aerobic capacity. We used bank voles [Clethrionomys (= Myodes) glareolus] from lines selected for high swim-induced aerobic metabolism (A) and unselected control lines (C). In a crossover design, we measured endurance running distance, aerobic capacity ( <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_2}{mathrm{max}}}}$</annotation></semantics> </math> ), peak speed (V_max) and respiratory exchange ratio in 98 animals fed standard rodent diet (14.5 kJ/g) or WD (20.5 kJ/g; 48% from carbohydrates, including 28% from added sucrose, and 39% from fat) for 2 days before the trials. The <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_2}{mathrm{max}}}}$</annotation></semantics> </math> , V_max and endurance distance were higher in A lines than in C lines. In A lines, endurance distance increased with V_max but not with <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_2}{mathrm{max}}}}$</annotation></semantics> </math> , whereas in C lines it increased more with <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_2}{mathrm{max}}}}$</annotation></semantics> </math> than with V_max. The WD treatment resulted in increased body mass (p = 0.006) and did not affect <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_2}{mathrm{max}}}}$</annotation></semantics> </math> (p = 0.4), but tended to decrease V_max (p = 0.04), endurance distance (p = 0.099), mass loss during the trials (p = 0.008) and, in A lines only, the respiratory exchange ratio (p = 0.02). These results show that the selection experiment provides a model of genetically distinct aerobic athletes and non-athletes, in whom exercise performance appears to be limited by different mechanisms. Regardless of the genetic background, short-term WD supplementation does not improve aerobic exercise performance and reduces the effectiveness of exercise as a method of weight loss.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144717801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypogravity simulation using the Variable Gravity Suspension System: A technical report.","authors":"Patrick Swain, Anthony Swain, Filipa Santos, Luke Hughes, Kirsty Lindsay, Ishbel Lomax, Nick Caplan","doi":"10.1113/EP092172","DOIUrl":"https://doi.org/10.1113/EP092172","url":null,"abstract":"<p><p>Human movement has evolved within Earth's gravitational environment (1 g; -9.81 m s^-2). Future human exploration of terrestrial bodies, including the Moon (0.17 g; -1.62 m s^-2) and Mars (0.38 g; -3.71 m s^-2), will require astronauts to live and work within reduced gravitational environments (hypogravity). Progressing understanding of the physiological and biomechanical implications of movement in hypogravity will play a key role in supporting the expansion of humanity to terrestrial bodies beyond Earth, within our solar system. Ground-based hypogravity analogues that enable the study of human movement are pivotal to developing knowledge in this field. Whole-body suspension can serve as a resource-efficient and accessible hypogravity analogue, yet only a limited number of such analogues exist globally. This technical report introduces a new hypogravity analogue facility: the Variable Gravity Suspension System (VGSS). The report introduces the VGSS and its theoretical framework, which enables simulation of both micro- and hypo-gravity, presents proof-of-concept data regarding its ability to simulate hypogravity, and demonstrates the ability of the VGSS to facilitate locomotive and jumping activities in simulated hypogravity.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144697958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrite supplementation alleviates cerebrovascular dysfunction in chronically stressed mice, but cognitive decline remains.","authors":"Emily Burrage, Tyler Coblentz, Saina S Prabhu, Nicole M Eminhizer, Ryan Childers, Randall W Bryner, Sara E Lewis, Brooke A Maxwell, Evan R DeVallance, Eric E Kelley, Paul D Chantler","doi":"10.1113/EP092501","DOIUrl":"https://doi.org/10.1113/EP092501","url":null,"abstract":"<p><p>This study aimed to determine whether sodium nitrite supplementation prevented chronic stress-induced cerebrovascular dysfunction and cognitive decline. We hypothesize that nitrite supplementation will prevent the oxidative environment and cerebrovascular dysfunction associated with chronic stress and maintain cognitive health. Eighteen-week-old male/female C57BL/6 mice underwent 8 weeks of control conditions or unpredictable chronic mild stress (UCMS) with or without sodium nitrite (50 mg/L) in the drinking water. Excised middle cerebral arteries (MCA) were mounted in a pressurized myobath and exposed to increasing concentrations of acetylcholine (ACh). Nitrite supplementation prevented the UCMS-induced impaired ACh response in the MCA. We examined xanthine oxidoreductase (XOR) as a potential mechanism by determining XOR protein abundance, activity, and hydrogen peroxide production in the liver and brain. Nitrite supplementation prevented the development of an oxidative environment within the liver, brain and cerebrovasculature. Assessment of working memory revealed that sodium nitrite did not fully prevent the impairment of cognitive function because of chronic stress. These data suggest that nitrite supplementation protects against stressed-induced cerebrovascular dysfunction by limiting the actions of oxidants, potentially via XOR, while improving NO bioavailability. However, nitrite was not sufficient to prevent cognitive impairment with chronic stress.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144697969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat therapy: Strategies to enhance thermal comfort without compromising benefits.","authors":"Christof A Leicht","doi":"10.1113/EP093030","DOIUrl":"https://doi.org/10.1113/EP093030","url":null,"abstract":"","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144689622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Empagliflozin does not prevent progression of Dent's disease type 1 in a mouse model.","authors":"Elise de Combiens, Nadia Frachon, Yohan Bignon, Marc Fila, Clément Brossard, Perrine Frère, Stéphane Lourdel","doi":"10.1113/EP092736","DOIUrl":"https://doi.org/10.1113/EP092736","url":null,"abstract":"<p><p>Dent's disease is a rare inherited renal disorder characterized by generalized proximal tubule dysfunction with low molecular weight proteinuria, hypercalciuria, and urinary loss of other solutes. The disease is progressive and leads to chronic kidney disease. To study the mechanisms involved in its progression, we generated a knock-in mouse model displaying a classical Dent's disease type 1 phenotype. Currently, no targeted therapy exists for Dent's disease; treatment strategies primarily aim to slow the progression of specific clinical aspects. Accordingly, empagliflozin [a sodium-glucose cotransporter 2 (SGLT2) inhibitor] known to exert nephroprotective effects and to slow down the decrease of the glomerular filtration rate in diabetic and non-diabetic patients with chronic kidney disease, was administered to the knock-in mice. We demonstrated that empagliflozin administration reduces renal and urinary levels of the marker of tubular damage, Lipocalin-2 (LCN2). However, we observed that this preventive treatment does not alleviate low molecular weight proteinuria, hypercalciuria, inflammation, renal fibrosis or the decline of the glomerular filtration rate. Overall, our findings suggest that SGLT2 inhibition with empagliflozin does not prevent the progression of Dent's disease type 1 towards chronic kidney disease.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144689620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of moderate altitude and nocturnal oxygen therapy on cerebrovascular function in patients with COPD: A randomized, crossover trial at 2048 m.","authors":"Dominic Gilliand, Tsogyal D Latshang, Sayaka S Aeschbacher, Fabienne Huber, Deborah Flueck, Mona Lichtblau, Stefanie Ulrich, Elisabeth D Hasler, Philipp M Scheiwiller, Julian Müller, Silvia Ulrich, Konrad E Bloch, Michael Furian","doi":"10.1113/EP093003","DOIUrl":"https://doi.org/10.1113/EP093003","url":null,"abstract":"<p><p>We investigated whether nocturnal oxygen therapy improves next-day cerebrovascular function in lowlanders with chronic obstructive pulmonary disease (COPD) staying at moderate altitude. This randomized, placebo-controlled single-blind crossover trial was performed in moderate-to-severe COPD patients [forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) <0.7; FEV₁ 30%-80% of predicted], living at <800 m a.s.l. and arterial oxygen saturation ( <math> <semantics><msub><mi>S</mi> <mrow><mi>p</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{S}_{{mathrm{p}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> ) measured with pulse oximetry ≥92%. Patients underwent assessments at 490 m and during two separate sojourns of 2 days at 2048 m, receiving either 3 L min^-1 nocturnal oxygen therapy or placebo in a randomized crossover design. At both altitudes, <math> <semantics><msub><mi>S</mi> <mrow><mi>p</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{S}_{{mathrm{p}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> , cerebral tissue oxygenation (CTO, measured by near-infrared spectroscopy), mean arterial blood pressure (MAP, measured by finger plethysmography) and middle cerebral artery systolic peak blood flow velocity (sMCAv, measured by transcranial Doppler ultrasound) were assessed while patients were quietly breathing with fraction of inspired O₂ ( <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{F}_{{mathrm{I}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> ) 0.21, with <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{F}_{{mathrm{I}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> 1.0, voluntarily hyperventilating, voluntarily hyperventilating with <math> <semantics><msub><mi>F</mi> <mrow><mi>I</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{F}_{{mathrm{I}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> 1.0, and during a head-up tilt. Overall, 18 patients (8 women) aged (mean ± SD) 65 ± 5 years, with FEV₁ 54.7% ± 13.9% predicted were analysed. At 2048 m under <math> <semantics><msub><mi>F</mi> <msub><mi>IO</mi> <mn>2</mn></msub> </msub> <annotation>${F}_{{mathrm{IO}}_{2}}$</annotation></semantics> </math> 0.21, patients became hypoxaemic ( <math> <semantics><msub><mi>S</mi> <mrow><mi>p</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{S}_{{mathrm{p}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> 90.3% ± 1.6%), while MAP, CTO and sMCAv remained unchanged compared with 490 m. All ventilatory manoeuvres at 2048 m induced greater increases in <math> <semantics><msub><mi>S</mi> <mrow><mi>p</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> <annotation>${{S}_{{mathrm{p}}{{{mathrm{O}}}_2}}}$</annotation></semantics> </math> compare","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144689619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}