Hypoxic cerebrovascular oxidative–nitrosative stress: Take my breath away DOI Creative Commons
Kirsten Møller

The Journal of Physiology, Journal Year: 2024, Volume and Issue: 602(21), P. 5717 - 5718

Published: March 11, 2024

Blood flow to the brain is highly regulated maintain a continuous supply of oxygen and nutrients ensure removal metabolic waste products. Accordingly, excursions in arterial carbon dioxide or tension will activate swift cerebrovascular responses aiming keep microenvironment stable. One first steps our understanding these underlying mechanisms was taken by Kety Schmidt (1948), who became measure global cerebral blood humans using inhaled nitrous oxide as tracer, reported marked increase following reduction inspired fraction during inhalation air mixed with dioxide. Several studies followed that took advantage various applications Kety–Schmidt technique Fick principle consolidate findings hypoxia- hypercapnia-induced changes human volunteers under different contexts, such at high altitude gas mixtures. In late 1970s, pial arteriolar dilatation hypoxia hypercapnia observed directly cranial window anaesthetized cats. Subsequent breakthroughs involved discovery hypoxia-inducible factors ubiquitous intracellular sensors initiators compensatory pathways, an activator factor degradation thus suppressor nitric one several important vasodilating agents released after activation pathways. Thus, astrocytes were recently reduce nitrite release (Christie et al., 2023). Moreover, induces relaxation pericytes ensuing capillary (Hartmann 2021); however, although pericyte (Hall Nature 2014), signalling has not been formally demonstrated dioxide-induced pericytes. this issue The Journal Physiology, Bailey al. (2024) address interplay between hypoxia/hypercapnia, haemodynamics oxidative–nitrosative stress. It profits from capacity elite apneists (free-divers) for prolonged breath-holding. cross-over design, 10 exposed themselves two maximal breath-holding sessions, which preceded normoxic normoventilation, whereas second hyperoxic hyperventilation. Using duplex ultrasound well sampling arterial, addition jugular bulb catheters, investigators compared flow, oxidative metabolism, uptake/output markers nitrosative stress hypoxaemic hyperoxaemic hypercapnia. Compared hypercapnia, net ascorbate radical lipid hydroperoxides, stress, increased Conversely, uptake nitrite, 'precursor' oxide, but lesser extent, indicating less consumption, Cerebral both lower results suggest role comparatively impaired response indicates nitrogen mediator vasodilatation As noted (2024), there are caveats reservations regarding non-randomized durations severity apnoea, non-steady-state end-apnoea, inevitable presence involuntary muscular activity. Nonetheless, rigorously conducted study contribute physiology pathophysiology haemodynamic regulation. First, present appear be line previous observations central function. Second, healthy to, diseases associated with, severe elucidated. obviously relevant freedivers, expose (whether voluntarily accidentally) Furthermore, obstructive sleep characterized repeated episodes partial complete upper airway obstruction, leading hypoxaemia disrupted sleep, notably risk stroke. Although sympathetic activity hypertension may also involved, future could whether lead ischaemia, infarction clinical injury patients. Finally, combined commonly occurs respiratory failure; here, should probably perceived potentially more dangerous brain, least terms than hyperoxaemia applied resuscitative purposes. Please note: publisher responsible content functionality any supporting information supplied authors. Any queries (other missing content) directed corresponding author article. No competing interests declared. K.M. conception design work, drafting work revising it critically intellectual final approval version submitted publication. agrees accountable all aspects work. Kirsten Møller received funding Novo Nordisk Fonden (ref. NNF20OC0065750), Danish Victims' Foundation 20-610-00103) Rigshospitalet's Board Research NA).

Language: Английский

The link between sleep bruxism and oxidative stress based on a polysomnographic study DOI Creative Commons
Michał Fułek, Weronika Frosztęga, Mieszko Więckiewicz

et al.

Scientific Reports, Journal Year: 2025, Volume and Issue: 15(1)

Published: Jan. 28, 2025

Oxidative stress is proven to increase cardiovascular risk and diminish healthy life expectancy. Sleep bruxism (SB) a prevalent masticatory muscle activity during sleep characterized by heterogeneous etiology inadequately recognized pathophysiology. Recent theories have proposed potential association between SB oxidative stress. The aim of the research was compare antioxidant status individuals with in contrast those without SB. A total 80 adults participated full-night polysomnography, assessed according American Academy Medicine (AASM) standards. Blood samples were subsequently drawn via venipuncture for analysis. Participants stratified into two groups based on their episode index (BEI). Using successive receiver operating characteristic (ROC) curves, optimal cut-off values identified, enabling detection correlations moderate (BEI > 2) severe 4) bruxism. In investigated group patients we observed relationship examined parameters: (TAS), advanced protein products (AOPP) thiobarbituric acid-reacting substances (TBARS). Low TAS (≤ 0.14 mM ≤ 0. 16 mM), high AOPP (≥ 82.44 µmol/l) TBARS 723.03 µmol/l ≥ 1585.45 serum levels result significantly higher parameters. related markers. Elevated markers lipid peroxidation may be associated endovascular damage bruxers, but further needed this topic.

Language: Английский

Citations

2
Cardiovascular and cerebral hemodynamics during static and dynamic breath-holding DOI
Jérémie Allinger, Guillaume Costalat,

Catherine Chiron

et al.

European Journal of Applied Physiology, Journal Year: 2025, Volume and Issue: unknown

Published: March 12, 2025

Language: Английский

Citations

0
Phosphodiesterase inhibition restoreshypoxia-induced cerebrovascular dysfunction subsequent to improved systemic redox homeostasis: A randomized, double-blind, placebo-controlled crossover study DOI
Benjamin S. Stacey, Christopher J. Marley, Hayato Tsukamoto

et al.

Journal of Cerebral Blood Flow & Metabolism, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 25, 2025

To what extent sildenafil, a selective inhibitor of the type-5 phosphodiesterase modulates systemic redox status and cerebrovascular function during acute exposure to hypoxia remains unknown. address this, 12 healthy males (aged 24 ± 3 y) participated in randomized, placebo-controlled crossover study involving both normoxia (60 min) (FiO2 = 0.14), followed by oral administration 50 mg sildenafil placebo (double-blinded). Venous blood was sampled for ascorbate radical (A•-: electron paramagnetic resonance spectroscopy) nitric oxide metabolites (NO: ozone-based chemiluminescence). Transcranial Doppler ultrasound employed determine middle cerebral artery velocity (MCAv), delivery oxygen (CDO2), dynamic autoregulation (dCA) reactivity hypo/hypercapnia (CVRCO2HYPO/HYPER). Cortical oxyhemoglobin (cO2Hb) oxygenation index (OI) were assessed using pulsed continuous wave near infra-red spectroscopy. Hypoxia decreased total plasma NO (P 0.008), CDO2 <0.001) cO2Hb 0.005). In hypoxia, selectively reduced A•- 0.018) MCAV 0.018), increased dCA metrics low-frequency phase 0.029) CVRCO2HYPER 0.007) compared hypoxia-placebo. Collectively, these findings provide evidence PDE-5 inhibitory pathway that enhances select aspects subsequent improvement homeostasis independent altered vascular bioavailability.

Language: Английский

Citations

0
From bedside to seaside: An academic's attempt at freediving DOI Creative Commons
Anthony R. Bain

Experimental Physiology, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 19, 2025

Early into my PhD at the University of British Columbia, supervisor, Prof. Philip Ainslie, asked me to join a 2-week research trip Split, Croatia. The answer was course yes. purpose still unclear me, but it didn't matter, as prospect paid overseas adventure reason enough. I later informed that we would be studying elite freedivers. fully understand what an 'elite freediver' was, enthusiasm not dampened. When arrived in Croatia were met by our local host (and freediving expert), Dujic Zeljko. We had brief period acclimate his lab, and testing began next day – there no time for jetlag or tourist. On first experimentation, quickly learned freediver was. Foremost freedivers are athletes. These athletes deeply committed their sport, striving only optimize performance also advance understanding physiology safety aspects through research. sport operates differently from any other conventional sports organization. Official competitions records sanctioned under International Association Development Apnea, AIDA short (when abbreviated French) (www.aidainternational.org). formed 1992, shortly after interest record attempts ballooned movie Big Blue. As writing, approximately 3000 registered compete regular AIDA-sanctioned (this number does include hundreds thousands recreational freedivers). Athletes 10 separate disciplines broadly characterized vertical depth, horizontal swim distance (usually pool), maximal breath hold duration. Each discipline involves unique stressor, particularly when depth is involved (more on later), unifying factor extended period. hold, accompanying physiological stress, initially brought us study this (the many follow), interested arterial blood gas profile brain flow regulation. With holds averaging slightly longer than 5 min, primary finding termination cerebral oxygen delivery maintained, despite average end-breath partial pressure 30 mmHg (Willie et al., 2015) very close 50% saturation theoretical limit consciousness (Nunn, 1987). preserved proportional increase tightly compensated reductions content. This tip iceberg, unknown time, fons origo trajectory continued now almost decade past graduation. Through subsequent expeditions with (see Figure 1 representative look instrumental set-up freedivers), gained insight numerous fundamental questions, including impact hypercapnia hypoxia metabolism (Bain 2016, Bain, Barak, 2017), ergogenic effect beta blockers (substances banned AIDA) duration (Hoiland influence lung volume (Bain, 2017; Stembridge oxidative stress (Bailey 2024 Hoiland, 2018), how carotid body 2015). A review these findings more related static (static meaning remaining stationary) published journal Drvis, 2018). trips (to date four total spanning 2013 2022) offered wealth academic experience insight, completing considered 'expert' physiology. But hadn't done dedicated convincing practicing myself. felt like fraud. knew one I'd need give training good attempt, watching over years sparked inner sportsman's desire test own abilities. Thankfully, armed arsenal knowledge gave leg up. finally found some practice before summer holiday Nova Scotia, 2024. motivation garnered convinced brother two apnoea annual 'feats strength' yearly event moonlights gauge who physically deteriorating faster age. agreed upon closely resembling Constant Weight No Fins (CNF) AIDA, hold. Unofficial Vegas odds favourite discipline, he seasoned ocean swimmer surfer, while perceived advantage given prior exposure sport. Another hotly debated consideration betting missing spleen (after splenectomy 2003), which tentatively puts him disadvantage acts reservoir oxygen-rich red cells, released during (Inoue 2013; Schagatay 2001). Indeed, Bajau divers Southeast Asia, often referred 'sea nomads', evolved genetic alterations have larger spleens adaptation lifestyle (Ilardo To start training, key, is, learning become comfortable uncomfortable, said differently, your conscious (higher centres) deprioritize subconscious mounting neural traffic. prolonged evokes powerful sympathetic response, intensifying respiratory centres medulla, afferents chemoreception (reviewed 2018]) culminating increased drive breathe. Occurring around ∼3 min (albeit widely variable), reflexive breathe intensifies point where diaphragm involuntarily contracts usually involuntary breathing movement (or IBM short). most naïve holders will break. However, repeated exposures, you can learn tolerate IBMs continue so-called 'struggle phase' called 'easy phase'. each able few breaking. 'elite' level, up 100 may occur breaking, getting better. Interestingly, surprised discover arrival provide sense dyspnoea relief. There data suggesting improve oxygenation increases venous return (Cross 2013). untested theory momentarily reduce stretch receptors lung. Regardless, confiding personal record-breaking apnoeists National Croatian team, am alone feeling relief onset IBMs. transient 'relief' IBMs, important stay relaxed. leads valuable aspect mental component. Learning appropriate relaxation techniques evident best entered state 'Zen' attempt. Relaxation serve interconnected purposes. attenuated, second provides conservation reducing heart rate therefore myocardial consumption. mechanism play likely identical central command exercise lower absolute intensity (Raven 2002). calm throughout apnoea, becoming limited measurable bleak. That term (e.g., months years) adaptations blunted ventilatory chemoreflex conflicting this, reviewed al. (2018)), volumes (mainly pack hold) (Ferretti & Costa, size (Yang heightened mammalian dive response (Ostrowski 2012). 'competition' day, started apnoea. conserving effects reflex bradycardia distribution flow), ideally been performed water face submerged, events. guidance (authority) wives family, dry land, facial cooling. submaximal preparatory minutes custom divers, dramatically attenuate initial 'shock/stress' While untested, theoretically cerebrovascular conditioning effects. Besides inclusion holds, provided further advice brother. Because risk shallow blackout (Bart Lau, 2025), included deep breathing/induced hypocapnia immediately Knowing (elevated P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ), especially early stages oxy-haemoglobin begins decline, starting hypocapnic advantageous. In end, easy win respectable (for novice) 4 8 s. My mustered measly 3 s notably similar 'training'. His breaking probably coincided (he IBMs), common motivated novice breathholders. next. Unlike conducted specific competition. mistake, myself land better nothing. involve stressors compared simple Swimming buoyancy efficiency essential minimize use production metabolic CO2. Moreover, equalization gain sort depth. m descent equivalent adding entire atmospheric (∼760 mmHg). air cavity squeeze descending explained Boyle's law middle ear (sinus pressure, congested, issue). Failure equalize lead barotrauma damage eardrum surrounding structures. Trained apply different Frenzel manoeuvre (Wolber 2021), do variations Valsalva swallowing. key without losing volume. descend extreme depths CNF 290 m). due inadequate present, likelihood severe pulmonary commonly observed reaching >200 m) concern. relatively conditions dive, bay's maximum being dives just m. potential considered. cause rapid reduction ascent, barometric halving (compared atmospheric) surface level. such, events, all standby medical personnel surface. For successful, must showing signs impending actual loss consciousness, such disorientation, unresponsiveness motor control issues. Spotters monitor preliminary indicators ensure diver's safety. Unfortunately, insufficient funding 'Feats Strength' competition did allow implementation measures. Therefore, adhered strict hyperventilation protocol diving (elite avoid dive). diving, abolished, cue resurface lost. cognisant dangers cautiously. came dropped anchor line attached buoy, goal collect sand bottom proof descent. then move deeper successful attempts. went easily handful below. less however, abysmal. scuba doing proved much difficult. descended 4–5 paused, trying equalize, efforts unsuccessful, come rope cannot used assistance, making uniquely challenging. combination maintaining control, holding attempting overwhelming. round ended soon began. turn, reflection 'lived experience' distinct physiological, physical psychological challenges dive. Even (Figure 2) typically lasts 2–4 its intense demands. (Conversely, 11:35 min.) case, extra energy spent ultimately became undoing. respectful translation hand, poor comfort level water, combined equalization, clear path victory. unofficial correct house always wins), respects, feel academic, lived unexpected questions explore. First, impacts apnoeas permit duration, they quantifiable? Additionally, mechanisms movements (at least me)? Are challenging tackle, think I'll success addressing them certainly Sole author. None declared. received work.

Language: Английский

Citations

0
Nutritional Recommendations for Breath-Hold Divers DOI Creative Commons

Ivan Drviš,

Dario Vrdoljak, Nikola Foretić

et al.

Applied Sciences, Journal Year: 2025, Volume and Issue: 15(5), P. 2384 - 2384

Published: Feb. 23, 2025

Breath-hold diving (BHD) is defined as enduring apnea for more than 4 min. It characterized by resistance of reactive oxygen species, reduced sensitivity to hypoxia, and low mitochondrial consumption. The energetic demands different BHD disciplines (static, dynamic, spearfishing) are various. Hence, the nutrition these athletes may play an important role on their performance. main aim this study examine propose recommendations specific population. Also, divide according spearfishing). Mediterranean alkaline diet could represent appropriate diet. Nutritional requirements differ between freediving (static dynamic) spearfishing, mainly because workload. spearfishing includes multiple consecutive dives hence has recommendations. However, proper freedivers based a variety natural foods that support acid–base balance, provide stable source energy, facilitate quality recovery. By adopting healthy eating habits diet, along with regular hydration adapting your needs diving, divers can improve performance ensure long-term health.

Language: Английский

Citations

0
Spinal pain prevalence and associated determinants: A population‐based study using the National Survey for Wales DOI Creative Commons
David Byfield, Benjamin S. Stacey, Hywel T. Evans

et al.

Physiological Reports, Journal Year: 2024, Volume and Issue: 12(21)

Published: Oct. 29, 2024

Abstract Spinal pain (SP) remains the leading cause of disability worldwide. The present study aimed to establish a current prevalence SP and associated determinants in Wales by retrospectively analyzing data from National Survey for Dataset (NSWD). NSWD is large‐scale cross‐sectional, representative sample adults across Wales, UK. A univariable multivariable regression analysis was carried out on self‐reported answers health well‐being questions contained within (2016–2020) determine strength association various comorbidities related spinal pain. total population 38,954 were included analysis. interview responses 21,735 females 17,219 males. 4.95% (95% CI: 4.74%–5.15%) with 847 males (4.92%, 4.60%–5.24%) 1082 (4.98%, 4.69%–5.27%) reporting age group highest 70+ years both (5.44%, 4.82%–6.07%) (5.95%, 5.37%–6.54%). between reaches its peak at 50–59 an adjusted Odds Ratio (aOR) 3.74 ( p = <0.001), that decreases slightly 60–69 years. For NSWD, significant associations confirmed for: mental illness (aOR 1.42, migraine 2.73, nervous system issues 1.61, arthritis 1.30, <0.001) bones/joints/muscles 1.93, <0.001). lifestyle factors, smokers 1.41, ex‐smokers 1.23, 0.003). This demonstrates low when compared global estimates strong variety determinants. still represents societal burden these findings may help inform public initiatives encourage prevention evidence‐based interventional strategies ultimately, improve quality life those suffering Wales.

Language: Английский

Citations

1
Hypoxia 2023: physiological mechanisms of adaptation DOI
Mike Stembridge, Philip N. Ainslie

The Journal of Physiology, Journal Year: 2024, Volume and Issue: 602(21), P. 5405 - 5407

Published: Sept. 19, 2024

Language: Английский

Citations

0
Hypoxic cerebrovascular oxidative–nitrosative stress: Take my breath away DOI Creative Commons
Kirsten Møller

The Journal of Physiology, Journal Year: 2024, Volume and Issue: 602(21), P. 5717 - 5718

Published: March 11, 2024

Blood flow to the brain is highly regulated maintain a continuous supply of oxygen and nutrients ensure removal metabolic waste products. Accordingly, excursions in arterial carbon dioxide or tension will activate swift cerebrovascular responses aiming keep microenvironment stable. One first steps our understanding these underlying mechanisms was taken by Kety Schmidt (1948), who became measure global cerebral blood humans using inhaled nitrous oxide as tracer, reported marked increase following reduction inspired fraction during inhalation air mixed with dioxide. Several studies followed that took advantage various applications Kety–Schmidt technique Fick principle consolidate findings hypoxia- hypercapnia-induced changes human volunteers under different contexts, such at high altitude gas mixtures. In late 1970s, pial arteriolar dilatation hypoxia hypercapnia observed directly cranial window anaesthetized cats. Subsequent breakthroughs involved discovery hypoxia-inducible factors ubiquitous intracellular sensors initiators compensatory pathways, an activator factor degradation thus suppressor nitric one several important vasodilating agents released after activation pathways. Thus, astrocytes were recently reduce nitrite release (Christie et al., 2023). Moreover, induces relaxation pericytes ensuing capillary (Hartmann 2021); however, although pericyte (Hall Nature 2014), signalling has not been formally demonstrated dioxide-induced pericytes. this issue The Journal Physiology, Bailey al. (2024) address interplay between hypoxia/hypercapnia, haemodynamics oxidative–nitrosative stress. It profits from capacity elite apneists (free-divers) for prolonged breath-holding. cross-over design, 10 exposed themselves two maximal breath-holding sessions, which preceded normoxic normoventilation, whereas second hyperoxic hyperventilation. Using duplex ultrasound well sampling arterial, addition jugular bulb catheters, investigators compared flow, oxidative metabolism, uptake/output markers nitrosative stress hypoxaemic hyperoxaemic hypercapnia. Compared hypercapnia, net ascorbate radical lipid hydroperoxides, stress, increased Conversely, uptake nitrite, 'precursor' oxide, but lesser extent, indicating less consumption, Cerebral both lower results suggest role comparatively impaired response indicates nitrogen mediator vasodilatation As noted (2024), there are caveats reservations regarding non-randomized durations severity apnoea, non-steady-state end-apnoea, inevitable presence involuntary muscular activity. Nonetheless, rigorously conducted study contribute physiology pathophysiology haemodynamic regulation. First, present appear be line previous observations central function. Second, healthy to, diseases associated with, severe elucidated. obviously relevant freedivers, expose (whether voluntarily accidentally) Furthermore, obstructive sleep characterized repeated episodes partial complete upper airway obstruction, leading hypoxaemia disrupted sleep, notably risk stroke. Although sympathetic activity hypertension may also involved, future could whether lead ischaemia, infarction clinical injury patients. Finally, combined commonly occurs respiratory failure; here, should probably perceived potentially more dangerous brain, least terms than hyperoxaemia applied resuscitative purposes. Please note: publisher responsible content functionality any supporting information supplied authors. Any queries (other missing content) directed corresponding author article. No competing interests declared. K.M. conception design work, drafting work revising it critically intellectual final approval version submitted publication. agrees accountable all aspects work. Kirsten Møller received funding Novo Nordisk Fonden (ref. NNF20OC0065750), Danish Victims' Foundation 20-610-00103) Rigshospitalet's Board Research NA).

Language: Английский

Citations

0