Ventilatory acclimatization to hypoxia in deer mice native to high altitudes
Bibliographic record
Abstract
Hypoxia at high altitudes constrains O 2 supply to support metabolism, thermoregulation in the cold, and the aerobic scope needed for exercise. Many highland taxa appear to have physiological specializations for overcoming these challenges, but relatively little is known about the importance of hypoxia acclimation responses in high‐altitude natives, such as ventilatory acclimatization to hypoxia (VAH) and erythropoiesis. Highland taxa often possess a high haemoglobin‐O 2 binding affinity, which safeguards arterial O 2 saturation (SaO 2 ) and tissue O 2 delivery in hypoxia, but could foreseeably affect hypoxia acclimation responses. We examined this issue by comparing captive populations of deer mice ( Peromyscus maniculatus ) from high and low altitudes. Mice from each population were acclimated to normoxia and moderate hypoxia (12 kPa O 2 , simulating the PO 2 at the native altitude of highlanders at 4300m) for 6–8 weeks. Highland mice were also acclimated to more severe hypoxia (9 kPa, the PO 2 at ~7000m), which induces the same SaO 2 in highlanders that lowlanders experience at 12 kPa. In lowlanders, hypoxia acclimation augmented the hypoxic ventilatory response (HVR), increased SaO 2 in hypoxia, blunted the hypoxic depression of body temperature, increased blood [haemoglobin], and induced right ventricle hypertrophy (a sign of maladaptive pulmonary hypertension). Hypoxia acclimation had little effect on the HVR in highlanders, such that the hypoxic control of breathing appeared to be fixed like that in hypoxia‐acclimated lowlanders. Right ventricle hypertrophy did not occur in either moderate or severe hypoxia in highlanders, suggesting that they have blunted hypoxic pulmonary vasoconstriction and hypertension. The increase in blood [haemoglobin] was lower in highlanders than in lowlanders at 12 kPa, but highlanders mounted a robust increase in severe hypoxia (9 kPa), suggesting that differences in SaO 2 and not the erythropoietic process contribute to differences in blood [haemoglobin] between populations. Therefore, high‐altitude adaptation appears to have blunted several hypoxia acclimation responses in deer mice. Support or Funding Information Supported by NSERC of Canada.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".