scholarly journals Does the broad nature of sympathetic discharge affect our understanding regarding the impact of intermittent hypoxia on neurovascular transduction?

2020 ◽  
Vol 598 (11) ◽  
pp. 2055-2057 ◽  
Author(s):  
Stephen A. Klassen ◽  
Chad C. Wiggins ◽  
Jonathon W. Senefeld
Keyword(s):  
Intermittent Hypoxia ◽  
The Impact ◽  
Sympathetic Discharge

Daily acute intermittent hypoxia enhances phrenic motor output and stimulus-evoked phrenic responses in rats

2021 ◽  
Author(s):  
Raphael Rodrigues Perim ◽  
Michael D. Sunshine ◽  
Joseph F. Welch ◽  
Juliet Santiago ◽  
Ashley Holland ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Phrenic Nerve ◽  
Intermittent Hypoxia ◽  
Neural Control ◽  
Respiratory Cycle ◽  
Evoked Responses ◽  
Nerve Activity ◽  
Synaptic Inputs ◽  
Phrenic Nerve Activity ◽  
The Impact

Plasticity is a hallmark of the respiratory neural control system. Phrenic long-term facilitation (pLTF) is one form of respiratory plasticity characterized by persistent increases in phrenic nerve activity following acute intermittent hypoxia (AIH). Although there is evidence that key steps in the cellular pathway giving rise to pLTF are localized within phrenic motor neurons (PMNs), the impact of AIH on the strength of breathing-related synaptic inputs to PMNs remains unclear. Further, the functional impact of AIH is enhanced by repeated/daily exposure to AIH (dAIH). Here, we explored the effects of AIH vs. 2 weeks of dAIH preconditioning on spontaneous and evoked responses recorded in anesthetized, paralyzed (with pancuronium bromide) and mechanically ventilated rats. Evoked phrenic potentials were elicited by respiratory cycle-triggered lateral funiculus stimulation at C2 delivered prior to- and 60 min post-AIH (or an equivalent time in controls). Charge-balanced biphasic pulses (100 µs/phase) of progressively increasing intensity (100 to 700 µA) were delivered during the inspiratory and expiratory phases of the respiratory cycle. Although robust pLTF (~60% from baseline) was observed after a single exposure to moderate AIH (3 x 5 min; 5 min intervals), there was no effect on evoked phrenic responses, contrary to our initial hypothesis. However, in rats preconditioned with dAIH, baseline phrenic nerve activity and evoked responses were increased, suggesting that repeated exposure to AIH enhances functional synaptic strength when assessed using this technique. The impact of daily AIH preconditioning on synaptic inputs to PMNs raises interesting questions that require further exploration.

scholarly journals Therapeutic potential of intermittent hypoxia: a matter of dose

2014 ◽  
Vol 307 (10) ◽  
pp. R1181-R1197 ◽  
Author(s):  
Angela Navarrete-Opazo ◽  
Gordon S. Mitchell
Keyword(s):  
Intermittent Hypoxia ◽  
Therapeutic Potential ◽  
Therapeutic Effects ◽  
Extensive Literature ◽  
Beneficial Effects ◽  
Metabolic Bone ◽  
Clinical Disorders ◽  
The Subject ◽  
Critical Characteristics ◽  
The Impact

Intermittent hypoxia (IH) has been the subject of considerable research in recent years, and triggers a bewildering array of both detrimental and beneficial effects in multiple physiological systems. Here, we review the extensive literature concerning IH and its impact on the respiratory, cardiovascular, immune, metabolic, bone, and nervous systems. One major goal is to define relevant IH characteristics leading to safe, protective, and/or therapeutic effects vs. pathogenesis. To understand the impact of IH, it is essential to define critical characteristics of the IH protocol under investigation, including potentially the severity of hypoxia within episodes, the duration of hypoxic episodes, the number of hypoxic episodes per day, the pattern of presentation across time (e.g., within vs. consecutive vs. alternating days), and the cumulative time of exposure. Not surprisingly, severe/chronic IH protocols tend to be pathogenic, whereas any beneficial effects are more likely to arise from modest/acute IH exposures. Features of the IH protocol most highly associated with beneficial vs. pathogenic outcomes include the level of hypoxemia within episodes and the number of episodes per day. Modest hypoxia (9–16% inspired O2) and low cycle numbers (3–15 episodes per day) most often lead to beneficial effects without pathology, whereas severe hypoxia (2–8% inspired O2) and more episodes per day (48–2,400 episodes/day) elicit progressively greater pathology. Accumulating evidence suggests that “low dose” IH (modest hypoxia, few episodes) may be a simple, safe, and effective treatment with considerable therapeutic potential for multiple clinical disorders.

scholarly journals Intermittent Hypoxia Increases the Severity of Bleomycin-Induced Lung Injury in Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Thomas Gille ◽  
Morgane Didier ◽  
Cécile Rotenberg ◽  
Eva Delbrel ◽  
Dominique Marchant ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pulmonary Fibrosis ◽  
Pulmonary Edema ◽  
Cell Apoptosis ◽  
Lung Fibrosis ◽  
Intermittent Hypoxia ◽  
Chronic Intermittent Hypoxia ◽  
Obstructive Sleep ◽  
The Impact ◽  
Lung Oxidative Stress

Background. Severe obstructive sleep apnea (OSA) with chronic intermittent hypoxia (IH) is common in idiopathic pulmonary fibrosis (IPF). Here, we evaluated the impact of IH on bleomycin- (BLM-) induced pulmonary fibrosis in mice. Methods. C57BL/6J mice received intratracheal BLM or saline and were exposed to IH (40 cycles/hour; FiO2 nadir: 6%; 8 hours/day) or intermittent air (IA). In the four experimental groups, we evaluated (i) survival; (ii) alveolar inflammation, pulmonary edema, lung oxidative stress, and antioxidant enzymes; (iii) lung cell apoptosis; and (iv) pulmonary fibrosis. Results. Survival at day 21 was lower in the BLM-IH group (p<0.05). Pulmonary fibrosis was more severe at day 21 in BLM-IH mice, as assessed by lung collagen content (p=0.02) and histology. At day 4, BLM-IH mice developed a more severe neutrophilic alveolitis, (p<0.001). Lung oxidative stress was observed, and superoxide dismutase and glutathione peroxidase expression was decreased in BLM-IH mice (p<0.05 versus BLM-IA group). At day 8, pulmonary edema was observed and lung cell apoptosis was increased in the BLM-IH group. Conclusion. These results show that exposure to chronic IH increases mortality, lung inflammation, and lung fibrosis in BLM-treated mice. This study raises the question of the worsening impact of severe OSA in IPF patients.

scholarly journals Episode Frequency Determines the Impact of Chronic Intermittent Hypoxia on Phrenic Long Term Facilitation

2017 ◽  
Vol 31 (S1) ◽  
Author(s):  
Elisa Janine Gonzalez‐Rothi ◽  
Raphael Rodrigues Perim ◽  
Arash Tadjalli ◽  
Alec K Simon ◽  
Marissa Ciesla ◽  
...  
Keyword(s):  
Intermittent Hypoxia ◽  
Chronic Intermittent Hypoxia ◽  
Episode Frequency ◽  
Long Term Facilitation ◽  
The Impact

scholarly journals Obstructive Sleep Apnea and Circulating Biomarkers of Oxidative Stress: A Cross-Sectional Study

Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 476
Author(s):  
Bernardo U. Peres ◽  
AJ Hirsch Allen ◽  
Aditi Shah ◽  
Nurit Fox ◽  
Ismail Laher ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiovascular Disease ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Intermittent Hypoxia ◽  
Smoking History ◽  
Obstructive Sleep ◽  
History Of ◽  
Statin Usage ◽  
The Impact

Oxidative stress (OS) drives cardiometabolic diseases. Intermittent hypoxia consistently increases oxidative stress markers. Obstructive sleep apnea (OSA) patients experience intermittent hypoxia and an increased rate of cardiovascular disease, however, the impact of OSA on OS markers is not clear. The objective was to assess relationships between OSA severity and biomarker levels. Patients with suspected OSA referred for a polysomnogram (PSG) provided fasting blood sample. Plasma levels of 8-isoprostane, 8-hydroxydeoxyguanosine (8-OHdG), and superoxide dismutase (SOD) were measured. The relationship between OSA and OS was assessed both before and after controlling for confounders (age, sex, smoking history, history of cardiovascular disease, ethnicity, diabetes, statin usage, body mass index (BMI)). 402 patients were studied (68% male, mean age ± SD = 50.8 ± 11.8 years, apnea-hypopnea index (AHI) = 22.2 ± 21.6 events/hour, BMI = 31.62 ± 6.49 kg/m2). In a multivariable regression, the AHI significantly predicted 8-isoprostane levels (p = 0.0008) together with age and statin usage; AHI was not a predictor of 8-OHdG or SOD. Female sex (p < 0.0001) and no previous history of cardiovascular disease (p = 0.002) were associated with increased antioxidant capacity. Circulating 8-isoprostane levels may be a promising biomarker of the severity of oxidative stress in OSA patients. Prospective studies are needed to determine whether this biomarker is associated with long-term cardiometabolic complications in OSA.

scholarly journals Intermittent hypoxia-induced endothelial barrier dysfunction requires ROS-dependent MAP kinase activation

2014 ◽  
Vol 306 (8) ◽  
pp. C745-C752 ◽  
Author(s):  
Vladislav V. Makarenko ◽  
Peter V. Usatyuk ◽  
Guoxiang Yuan ◽  
May M. Lee ◽  
Jayasri Nanduri ◽  
...  
Keyword(s):  
Barrier Function ◽  
Intermittent Hypoxia ◽  
Map Kinases ◽  
Fiber Formation ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Barrier Dysfunction ◽  
Endothelial Barrier Dysfunction ◽  
The Impact ◽  
Junction Proteins

The objective of the present study was to determine the impact of simulated apnea with intermittent hypoxia (IH) on endothelial barrier function and assess the underlying mechanism(s). Experiments were performed on human lung microvascular endothelial cells exposed to IH-consisting alternating cycles of 1.5% O2 for 30s followed by 20% O2 for 5 min. IH decreased transendothelial electrical resistance (TEER) suggesting attenuated endothelial barrier function. The effect of IH on TEER was stimulus dependent and reversible after reoxygenation. IH-exposed cells exhibited stress fiber formation and redistribution of cortactin, vascular endothelial-cadherins, and zona occludens-1 junction proteins along with increased intercellular gaps at cell-cell boundaries. Extracellular signal-regulated kinase (ERK) and c-jun NH2-terminal kinase (JNK) were phosphorylated in IH-exposed cells. Inhibiting either ERK or JNK prevented the IH-induced decrease in TEER and the reorganization of the cytoskeleton and junction proteins. IH increased reactive oxygen species (ROS) levels, and manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride, a membrane-permeable antioxidant, prevented ERK and JNK phosphorylation as well as IH-induced changes in endothelial barrier function. These results demonstrate that IH via ROS-dependent activation of MAP kinases leads to reorganization of cytoskeleton and junction proteins resulting in endothelial barrier dysfunction.

Intermittent hypoxia reduces upper airway stability in lean but not obese Zucker rats

2007 ◽  
Vol 293 (1) ◽  
pp. R372-R378 ◽  
Author(s):  
Andrew D. Ray ◽  
Ulysses J. Magalang ◽  
Charles P. Michlin ◽  
Toshiyuki Ogasa ◽  
John A. Krasney ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Intermittent Hypoxia ◽  
Upper Airway ◽  
Zucker Rats ◽  
Obstructive Sleep ◽  
Obese Rats ◽  
Supramaximal Stimulation ◽  
Obese Zucker Rats ◽  
The Impact ◽  
Stimulation Of

Obstructive sleep apnea involves intermittent periods of airway occlusions that lead to repetitive oxygen desaturations. Exposure to chronic intermittent hypoxia (IH) in rats increases diurnal blood pressure and alters skeletal muscle physiology. The impact of IH on upper airway muscle function is unknown. We hypothesize that IH exposure increases upper airway collapsibility in rats due to alterations of the muscles surrounding the upper airway. Lean and obese rats were exposed to cyclic alterations in O2 levels (20.6%-5%) every 90 s, 8 h/day for 6 days/wk for 12 wk. Following the exposure period, arterial pressure was recorded via the tail artery in conscious unrestrained rats. Mean arterial pressure was increased in lean IH but not in obese IH-exposed Zucker rats ( P < 0.05). The pharyngeal pressure associated with airway collapse (Pcrit) was measured under anesthesia during baseline conditions and then during supramaximal stimulation of the hypoglossal nerve (cnXII). Baseline Pcrit was more positive (more collapsible) in lean but not obese rats following 12 wk of IH ( P < 0.05), while supramaximal stimulation of cnXII increased airway stability (decreased Pcrit) in both lean and obese Zucker rats following IH to levels that were similar to their respective room air controls. The in vitro peak tension and the expression of the individual myosin heavy chain isoforms from the upper airway muscles were unaltered following IH. We conclude that IH leads to increases in baseline collapsibility in lean Zucker rats exposed to IH by nonmyogenic mechanisms.

Modulation of the contractile responses of guinea pig isolated tracheal rings after chronic intermittent hypobaric hypoxia with and without cold exposure

2005 ◽  
Vol 99 (3) ◽  
pp. 1006-1011 ◽  
Author(s):  
Kaveri Chakrabarty ◽  
M. Fahim
Keyword(s):  
Smooth Muscle ◽  
High Altitude ◽  
Cold Exposure ◽  
Hypobaric Hypoxia ◽  
Intermittent Hypoxia ◽  
Contractile Response ◽  
Tracheal Smooth Muscle ◽  
Contractile Responses ◽  
Intermittent Hypobaric Hypoxia ◽  
The Impact

Previous studies have documented that repetitive exposure to intermittent hypoxia, such as that encountered in preparation to high-altitude ascent, influences breathing. However, the impact of intermittent hypoxia on airway smooth muscle has not been explored. Ascents to high altitude, in addition to hypoxia, expose individuals to cold air. The objective of the present study is to examine the effect of chronic intermittent hypobaric hypoxia (CIH) and CIH combined with cold exposure (CIHC) on tracheal smooth muscle responses to various contractile and relaxant agonists. Experiments were performed on tracheal rings harvested from adult guinea pigs exposed either to CIH or CIHC [14 days (6 h/day) at barometric pressure of 350 mmHg with and without cold exposure of 5°C] or to room air (normoxia). CIH and CIHC attenuated maximum contractile responses to ACh compared with normoxia. The maximum contractile response to histamine decreased with CIH, whereas CIHC restored the response back to normoxia. Both CIH and CIHC attenuated maximum contractile responses to 5-HT. Altered contractile responses after CIH and CIHC were independent of epithelium. Isoproterenol-induced relaxation was not altered by CIH, whereas it was enhanced after CIHC, and these responses were independent of the epithelium. The data demonstrate that intermittent exposure to hypoxia profoundly influences contractile response of tracheal smooth muscle, and cold exposure can further modulate the response, implying the importance of cold at high altitude.

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