Peripheral Chemoreflex Regulates Post‐exercise Cardiac Vagal Reactivation in Healthy Humans and Patients with Pulmonary Arterial Hypertension
Notice bibliographique
Résumé
The fast post‐exercise heart rate recovery (HRR) is valid, reproducible, and widely used in clinical practice to assess the cardiac vagal function. However, the mechanisms that regulate it remain unclear. As the peripheral chemoreflex regulates resting cardiac activity, and this reflex is sensitized by physical exercise, we hypothesized that the peripheral chemoreflex could regulate the post‐exercise cardiac vagal reactivation in healthy humans. Additionally, we hypothesized that the peripheral chemoreflex could contribute to the reduction of post‐exercise cardiac vagal reactivation in a clinical population that has been associated with high peripheral chemosensitivity. To test the first hypothesis, seven young men underwent ramp exercise tests then, during recovery, randomly inhaled either 1) 12% of O 2 to stimulate the peripheral chemoreflex (i.e., hypoxia), 2) 100% of O 2 to inhibit the peripheral chemoreflex (i.e., hyperoxia), or 3) 21% of O 2 as control (i.e., normoxia). To test the second hypothesis, 14 adults with pulmonary arterial hypertension (PAH) underwent the same protocol, but randomly inhaled 100% or 21% of O 2 during recovery. Of note, all the subjects were blinded about the inspired O 2 concentration, which was changed slightly before the onset of recovery, not to disturb physiological responses during ramp exercise. ECG was registered and cardiac vagal reactivation was assessed via: 1) HRR, calculated as the difference between peak HR (HR peak ) and HR after 30 s (HRR30s) and 1 min (HRR1min) of recovery, and 2) HR variability (HRV), calculated as the root mean square of successive R‐R intervals difference (RMSSD) of 30‐s data segments throughout 5‐min of recovery. The chemoreflex sensitivity was assessed by the ventilatory response to transient nitrogen inhalation at rest. Healthy subjects showed similar HR peak among conditions (hypoxia: 156 ± 10 vs. hyperoxia: 153 ± 7 vs. normoxia: 156 ± 9 beats/min, mean ± SD, P = 0.60). Their HRR30s was lower in hypoxia (5 ± 5 beats/min) than hyperoxia (22 ± 6 beats/min, P <0.01) and normoxia (17 ± 8 beats/min, P <0.01). HRR1min and RMSSD throughout the recovery period were lower in hypoxia than hyperoxia (HRR1min: 19 ± 10 vs. 35 ± 6 beats/min, P = 0.03; RMSSD: 3.5 ± 1.1 vs. 5.4 ± 1.3 ms, P = 0.04). Patients with PAH showed higher chemosensitivity than young healthy men. Their HR peak was similar between conditions (hyperoxia: 147 ± 17 vs. normoxia: 148 ± 18 beats/min, P = 0.78). HRR30s (10 ± 5 vs. 5 ± 4 beats/min, P <0.001) and HRR1min (19 ± 9 vs. 15 ± 8 beats/min, P = 0.01) were higher in hyperoxia than normoxia. RMSSD was similar between conditions ( P = 0.60). Therefore, collectively, these results indicate that the peripheral chemoreflex regulates the post‐exercise cardiac vagal reactivation in healthy humans, and, also, mediates reduction of cardiac vagal reactivation in patients with PAH. Support or Funding Information The study was supported by São Paulo Research Foundation, FAPESP (2014/24294‐6; 2015/22198‐2)
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 | 0,001 | 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 ».