Cerebrovascular and ventilatory responses to acute isocapnic hypoxia in healthy aging and lung disease: effect of vitamin C

Hartmann, Sara E.; Waltz, Xavier; Kissel, Christine K.; Szabo, Lian; Walker, Brandie; Leigh, Richard; Anderson, Todd J.; Poulin, Marc J.

doi:10.1152/japplphysiol.00389.2015

Cited by 14 publications

(33 citation statements)

References 51 publications

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“…Differences between the findings of Hartmann et al. () and the present study may be explained by their use of TCD to obtain velocity and not flow, because recent evidence has suggested that the MCA dilates in hypoxia (Verbree et al., ), and that using only MCAv would ultimately underestimate CBF (Hoiland & Ainslie, ). In the present study, we observed dilatation within the ICA during both hypercapnia and acute hypoxia trials.…”

Section: Discussioncontrasting

confidence: 78%

“…() reported a decrease in MCAv reactivity to isocapnic hypoxia in young healthy participants after i.v . infusion of vitamin C (3 g; Hartmann et al., ). Differences between the findings of Hartmann et al.…”

Section: Discussionmentioning

confidence: 99%

“…There are, however, methodological issues associated with TCD, because the technique assumes that the diameter of the insonated intracranial vessel [e.g. middle cerebral artery (MCA)] remains constant in hypoxia (Hartmann et al., ). Given the recent criticisms of this assumption (reviewed by Hoiland & Ainslie, ), further assessment of the role of antioxidants in cerebrovascular regulation is warranted where both diameter and velocity are both assessed.…”

Section: Introductionmentioning

confidence: 99%

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UBC‐Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea level or high altitude

Hansen

Hoiland

Lewis

et al. 2018

Experimental Physiology

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Hypoxia is associated with an increase in systemic and cerebral formation of free radicals and associated reactants that may be linked to impaired cerebral vascular function and neurological sequelae. To what extent oral antioxidant prophylaxis impacts cerebrovascular function in humans throughout the course of acclimatization to the hypoxia of terrestrial high altitude has not been examined. Thus, the purpose of the present study was to examine the influence of orally ingested antioxidants at clinically relevant doses (vitamins C and E and α-lipoic acid) on cerebrovascular regulation at sea level (344 m; n = 12; female n = 2 participants) and at high altitude (5050 m; n = 9; female n = 2) in a randomized, placebo-controlled and double-blinded crossover design. Hypercapnic and hypoxic cerebrovascular reactivity tests of the internal carotid artery (ICA) were conducted at sea level, and global and regional cerebral blood flow (CBF; i.e. ICA and vertebral artery) were assessed 10-12 days after arrival at 5050 m. At sea level, acute administration of antioxidants did not alter cerebral hypoxic cerebrovascular reactivity (pre versus post: 1.5 ± 0.7 versus 1.2 ± 0.8%∆CBF/-%∆SpO2; P = 0.96) or cerebral hypercapnic cerebrovascular reactivity (pre versus post: 5.7 ± 2.0 versus 5.8 ± 1.9%∆CBF/∆mmHg; P = 0.33). Furthermore, global CBF (P = 0.43) and cerebral vascular conductance (ICA P = 0.08; vertebral artery P = 0.32) were unaltered at 5050 m after antioxidant administration. In conclusion, these data show that an oral antioxidant cocktail known to attenuate systemic oxidative stress failed to alter cerebrovascular function at sea level and CBF during acclimatization to high altitude.

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Section: Discussioncontrasting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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UBC‐Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea level or high altitude

Hansen

Hoiland

Lewis

et al. 2018

Experimental Physiology

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“…Similar isocapnic hypoxic ventilatory response at rest has been observed in young and older men and women (Smith et al 2001;Pokorski et al 2004;Vovk et al 2004), whereas others have reported reduced isocapnic hypoxic ventilatory responses in older men and women (Kronenberg & Drage, 1973;Serebrovskaya et al 2000;García-Río et al 2007;Hartmann et al 2015). The evaluation of the effect of ageing on the ventilatory response has led to contrasting results.…”

Section: Introductionmentioning

confidence: 81%

“…The cerebrovascular response to hypercapnia in older individuals was reported to be similar (Davis et al 1983;Kastrup et al 1998;Galvin et al 2010;Murrell et al 2012) or reduced (Yamamoto et al 1980;Reich & Rusinek, 1989) compared with younger individuals. Only one study recently evaluated the hypoxic cerebrovascular response in older individuals at rest and reported blunted cerebral blood velocity sensitivity to hypoxia compared with young control subjects (Hartmann et al 2015). At the muscle level, reduced oxygenation has been reported in older individuals at rest and during exercise in normoxia (Costes et al 1999;Ferri et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Effect of ageing on hypoxic exercise cardiorespiratory, muscle and cerebral oxygenation responses in healthy humans

Puthon

Bouzat

Robach

et al. 2017

Experimental Physiology

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What is the central question of this study? This study aimed to determine the effect of ageing on cardiorespiratory and tissue oxygenation responses to hypoxia during maximal incremental exercise. What is the main finding and its importance? Older healthy subjects had preserved hypoxic cardiorespiratory and tissue oxygenation responses at rest and during moderate exercise. At maximal exercise, they had a reduced hypoxic ventilatory response but similar maximal power output reduction compared with young individuals. This study suggests that until moderate exercise, hypoxic responses are preserved until the age of 70 years and therefore that ageing is not a contraindication for high-altitude sojourn. This study assessed the effects of ageing on cardiorespiratory and tissue oxygenation responses to hypoxia both at rest and during incremental maximal exercise. Sixteen young (20-30 years old) and 15 older healthy subjects (60-70 years old) performed two maximal incremental cycling tests in normoxia and hypoxia (inspiratory oxygen fraction 12%). Cardiorespiratory responses, prefrontal cortex and quadriceps tissue oxygenation (near-infrared spectroscopy) were measured during exercise as well as during hypercapnia at rest. The hypoxic ventilatory response was similar in young compared with older individuals at rest and during moderate-intensity exercise (50% maximal power output: young 0.9 ± 0.2 versus older 1.1 ± 0.8 l min % ; P > 0.05) but larger in young subjects during high-intensity exercise (maximal power output: 2.2 ± 0.8 versus 1.8 ± 1.1 l min % ; P < 0.05). The hypoxic cardiac response did not differ between groups both at rest and during exercise. During exercise in hypoxia, young subjects showed greater deoxygenation than older subjects, at both the prefrontal cortex and quadriceps levels. The hypoxia-induced reduction in maximal power output (young -32 ± 5% versus older -30 ± 6%; P > 0.05) and the hypercapnic responses did not differ between groups. Older healthy and active individuals below the age of 70 years have cardiorespiratory and tissue oxygenation responses to hypoxia similar to young individuals both at rest and during moderate-intensity exercise. Despite a lower hypoxic ventilatory response at maximal exercise, older individuals have similar oxygen desaturation and maximal power output reduction compared with young subjects.

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Hypoxia may be a determinative factor in COVID-19 progression

Grieb¹,

Świątkiewicz²,

Prus³

et al. 2021

Current Research in Pharmacology and Drug Discovery

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The disease which develops following SARS-CoV-2 virus infection, known as COVID-19, in most affected countries displays mortality from 1.5% to 9.8%. When leukocytosis due to granulocytosis, thrombocytopenia, and increased level of D-dimers are detected early during the disease course, they are accurate predictors of mortality. Based on the published observations that each of the aforementioned disturbances by itself may appear as a consequence of hypoxia, a hypothesis is presented that early hypoxia consequential to sleep apnea and/or blunted respiratory response to chemical stimuli is an early determinant of COVID-19 progression to the severe and critical stage. Further, it is noted that host-directed therapies which may counteract hypoxia and its early downstream effects are initiated only upon hospitalization of COVID-19 patients, which is too late to be fully effective. An example is anticoagulation treatment with low molecular weight heparin. Repurposing drugs which could counteract some early posthypoxic events, such as fluvoxamine, amantadine and N-acetylcysteine, for post-exposure prophylaxis of SARS-CoV-2 infection and early prehospital treatment of COVID-19, is indicated.

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Cerebrovascular and ventilatory responses to acute isocapnic hypoxia in healthy aging and lung disease: effect of vitamin C

Cited by 14 publications

References 51 publications

UBC‐Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea level or high altitude

UBC‐Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea level or high altitude

Effect of ageing on hypoxic exercise cardiorespiratory, muscle and cerebral oxygenation responses in healthy humans

Hypoxia may be a determinative factor in COVID-19 progression

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