Effect of Voluntary End‐Expiratory Apnea During Varying Chemoreflex Stress on Sympathetic Neural Recruitment Strategies
Notice bibliographique
Résumé
PURPOSE Sympathetic nervous system responses to voluntary apnea are increased by hypoxia and attenuated by hyperoxia. However, whether neural firing and recruitment strategies in response to apnea can be modified by hypoxia and/or hyperoxia were previously unknown. We examined the influence of chemoreceptor stimuli on sympathetic neural firing and recruitment strategies during voluntary end‐expiratory apnea. We hypothesized increases in the firing frequency and probability of low‐threshold axons during apnea would be exaggerated during hypoxia and attenuated during hyperoxia. METHODS Multi‐unit muscle sympathetic nerve activity (MSNA, microneurography) was measured in 10 young, healthy men (31±2 yrs, 25±1 kg/m 2 ). Data were collected at baseline and during maximal voluntary end‐expiratory apnea under normoxic (S p O 2 : 98±1%), hypoxic (F i O 2 : 0.17±0.01; S p O 2 : 82±1%), and hyperoxic (F i O 2 : 0.92±0.03; S p O 2 : 100±0%) conditions. Condition order was randomized and trials were separated by a minimum of 15‐min quiet normoxic rest. Action potential (AP) patterns were studied from the filtered raw signal using wavelet‐based methodology. Data are reported from the last 2‐min of baseline and during the second half of apnea, reflecting the time of highest MSNA. RESULTS There was an increase in multi‐unit MSNA (24±3 to 35±3 bursts/min, p=0.04) during normoxic apnea, which was due to an increase in the frequency and incidence of AP spikes (243±75 to 519±134 AP/min, p=0.048; 412±133 to 773±185 AP/100 heart beats, p=0.04). An increase in the probability of AP firing more than once per burst was also observed (p=0.01). There was an increase in multi‐unit MSNA (20±4 to 46±7 bursts/min, p<0.01) during hypoxic apnea that was due to an increase in the frequency and incidence of AP spikes (192±59 to 952±266 AP/min, p<0.01; 326±89 to 1212±327 AP/100 heart beats, p<0.01). Hypoxic apnea also resulted in an increase in the probability of AP firing more than once per burst (p<0.01). Hyperoxia attenuated any increase in MSNA with apnea, such that no changes in multi‐unit MSNA (24±4 to 28±5 bursts/min, p=0.14) nor frequency or incidence of AP spikes (155±35 to 253±71 AP/min, p=0.12; 249±61 to 502±188 AP/100 heart beats, p=0.28) were observed. Hyperoxia also attenuated any increase in the probability of AP firing more than once per burst (p=0.47). CONCLUSION These data are the first to show neural firing and recruitment strategies in response to voluntary end‐expiratory apnea are modified by hypoxia and hyperoxia. Our results demonstrate that hypoxic apnea increases the frequency and incidence of action potential spikes, as well as the probability of multiple within‐burst firing; whereas this response was suppressed when individuals were hyperoxic. These data may have important implications for neural control of the circulation in recreational activities (i.e. diving) and/or clinical conditions prone to apnea (i.e. sleep apnea). Support or Funding Information FUNDING: AHA #15SDG25080095, NIH HL130339, Natural Sciences and Engineering Research Council of Canada Discovery Grant program. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».