Carotid chemoreflex activity restrains post‐exercise cardiac autonomic control in healthy humans and in patients with pulmonary arterial hypertension
Bibliographic record
Abstract
Key points Dysfunction of post‐exercise cardiac autonomic control is associated with increased mortality risk in healthy adults and in patients with cardiorespiratory diseases. The afferent mechanisms that regulate the post‐exercise cardiac autonomic control remain unclear. We found that afferent signals from carotid chemoreceptors restrain the post‐exercise cardiac autonomic control in healthy adults and patients with pulmonary arterial hypertension (PAH). Patients with PAH had higher carotid chemoreflex sensitivity, and the magnitude of carotid chemoreceptor restraint of autonomic control was greater in patients with PAH as compared to healthy adults. The results demonstrate that the carotid chemoreceptors contribute to the regulation of post‐exercise cardiac autonomic control, and suggest that the carotid chemoreceptors may be a potential target to treat post‐exercise cardiac autonomic dysfunction in patients with PAH. Abstract Dysfunction of post‐exercise cardiac autonomic control predicts mortality, but its underlying mechanisms remain unclear. We tested whether carotid chemoreflex activity restrains post‐exercise cardiac autonomic control in healthy adults (HA), and whether such restraint is greater in patients with pulmonary arterial hypertension (PAH) who may have both altered carotid chemoreflex and altered post‐exercise cardiac autonomic control. Twenty non‐hypoxaemic patients with PAH and 13 age‐ and sex‐matched HA pedalled until 90% of peak work rate observed in a symptom‐limited ramp‐incremental exercise test. Recovery consisted of unloaded pedalling for 5 min followed by seated rest for 6 min. During recovery, subjects randomly inhaled either 100% O 2 (hyperoxia) to inhibit the carotid chemoreceptor activity, or 21% O 2 (normoxia) as control. Post‐exercise cardiac autonomic control was examined via heart rate (HR) recovery (HRR; HR change after 30, 60, 120 and 300 s of recovery, using linear and non‐linear regressions of HR decay) and HR variability (HRV; time and spectral domain analyses). As expected, the PAH group had higher carotid chemosensitivity and worse post‐exercise HRR and HRV than HA. Hyperoxia increased HRR at 30, 60 and 120 s and absolute spectral power HRV in both groups. Additionally, hyperoxia resulted in an accelerated linear HR decay and increased time domain HRV during active recovery only in the PAH group. In conclusion, the carotid chemoreceptors restrained recovery of cardiac autonomic control from exercise in HA and in patients with PAH, with the restraint greater for some autonomic indexes in patients with PAH.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".