Central-peripheral respiratory chemoreflex interaction changes with acclimatization to high altitude
Notice bibliographique
Résumé
Background: With chronic exposure to hypobaric hypoxia, the medullary (central) and arterial (peripheral) respiratory chemoreflexes become sensitized (i.e., ventilatory acclimatization). Whether the interaction between chemoreceptors is also altered has not been assessed. PURPOSE & HYPOTHESIS: We investigated the peripheral chemoreflex response to hypoxia at increasing arterial and central CO 2 tensions in humans at 1100 m (low altitude: Calgary, Canada) and after 7 days at 3800 m (high altitude: La Paz, Bolivia). We hypothesized that ventilatory acclimatization alters central and peripheral chemoreceptor interaction. METHOD: Seventeen participants (8 females; mean±SD age: 27±5 years) completed two repetitions of modified rebreathing with end-tidal PO 2 (P ET O 2 ) clamped at 150, 60, and 45 mmHg over two visits at each location. End-tidal PCO 2 (P ET CO 2 ), P ET O 2 , ventilation (V· E ), and saturation (S p O 2 ) were measured breath-by-breath by dual gas analyser, volume turbine, and pulse oximeter. The V· E vs. P ET CO 2 relationship in the hyperoxic test gave the central chemoreflex response to PCO 2 and the hypoxic tests provided combined central-peripheral chemoreflex responses. ANALYSIS: The slope of the V· E vs. P ET CO 2 (V· E S, L·min -1 ·mmHg -1 ) of each iso-oxic condition was obtained by fitting a piecewise model. Linear regression was used to determine peripheral chemoreflex sensitivity (PChS: L·min -1 ·mmHg -1 ·% S c O 2 -1 ) at each P ET CO 2 as previously described (Guluzade et al. 2023). These steps were repeated every 1 mmHg of P ET CO 2 to build a PChS vs. PCO 2 relationship for each participant. Individual PChS-P ET CO 2 relationships were fit with linear (additive) and polynomial (non-additive) functions. Akaike Information Criterion identified the best-fit model. Results: Two-way (isoxic condition x location) repeated measures analysis of variance revealed that V· E S rose from low-to-high altitude (p<0.001) and with isoxic PO 2 (p<0.001) from 4.0±2.1 to 7.2±5.4 L·min -1 ·mmHg -1 at 150 mmHg, 6.3±3.5 to 9.7±4.9 L·min -1 ·mmHg -1 at 60 mmHg, and 7.7±4.8 to 11.5±5.1 L·min -1 ·mmHg -1 at 45 mmHg. The PChS vs. P ET CO 2 relationship was best described by an additive (linear) model in 12 and 13 of 17 participants at low and high altitude, respectively. At low altitude, five participants had a hypo-additive interaction (decelerating polynomial), and, at high altitude, four participants exhibited hyper-additivity (accelerating polynomial). All five hypo-additive individuals became additive after a week at 3800 m and four additive participants became hyper-additive. Conclusion: Findings support differential between-participant respiratory chemoreflex interaction that is modified with acclimatization at high altitude in a hypo-to-hyper-additive manner. NSERC Discovery (D.A.K, RGPIN-2021-03980; T.A.D., RGPIN-2024-04182; R.J.A.W., RGPIN-2020-05312), UCalgary Transdisciplinary Connector and HBI RHISE grants. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
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Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| 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) | 0,000 | 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 tête enseignante, pas un consensus.
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