Tonic peripheral chemoreflex activation contributes to cardiac autonomic modulation at rest and impairs cardiac baroreflex sensitivity during orthostatic challenge in patients with pulmonary arterial hypertension
Notice bibliographique
Résumé
Patients with pulmonary arterial hypertension (PAH) often experience orthostatic hypotension, and this may be mediated, to some extent, by impaired baroreflex sensitivity (BRS). The impairment in BRS is possibly caused by multiple factors. Of note, however, accumulating evidence has supported that tonic peripheral chemoreflex activation plays a key role for autonomic impairment in diseases like systemic hypertension and heart failure, due to, in part, alterations that are also commonly found in PAH (e.g., inflammation and oxidative stress). Thus we sought to test two hypotheses: 1) patients with PAH present impaired BRS during an orthostatic challenge; 2) the peripheral chemoreflex is sensitized in patients with PAH and contributes to cardiac autonomic modulation and BRS at rest and BRS during an orthostatic challenge. Twenty non‐hypoxemic patients with PAH and 10 healthy controls (CON) were assessed. Peripheral chemosensitivity was measured via the ventilatory response to transient inhalation of pure nitrogen. Beat‐by‐beat heart rate (ECG) and arterial pressure (finger photoplethismography) were measured at seated rest and during a repeated sit‐to‐stand maneuver (six consecutive repetitions of 10‐s sit and 10‐s stand), while participants randomly inhaled 100% of O 2 to inhibit the peripheral chemoreflex tonic activity (i.e., hyperoxia), and 21% of O 2 as control (i.e., normoxia). Isocapnia was maintained via a rebreathing system. Cardiac autonomic modulation was quantified via heart rate variability (HRV) indexes, which were calculated in time and frequency domains. The C BRS was calculated at rest via sequence and alpha index methods, and during a sit‐to‐stand maneuver via sequence method. The PAH group showed significantly higher peripheral chemosensitivity (PAH: 0.32 ± 0.04 vs CON: 0.18 ± 0.02 L/%SpO 2 , P < 0.05) and significantly lower C BRS during the sit‐to‐stand maneuver, compared to the CON group. Peripheral chemoreflex inhibition via hyperoxia similarly increased HRV and C BRS in both groups at rest. In addition, hyperoxia significantly increased BRS during the sit‐to‐stand maneuver only in the PAH group, and then, the BRS was normalized (i.e., attained the CON group level). In summary, this study provides novel evidence that patients with PAH present low C BRS during an orthostatic challenge. Furthermore, data supports that the peripheral chemoreflex is sensitized and tonically contributes to cardiac autonomic modulation in patients with PAH at rest, and most notably, to impaired cBRS during an orthostatic challenge. Support or Funding Information The study was supported by São Paulo Research Foundation, FAPESP (2015/221982; 2017/077713) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 ».