Huff and Puff or Shut'er Down: Hypoxia‐Tolerant Mammals Respond Differently to Low Oxygen
Bibliographic record
Abstract
Unlike most mammals, ground squirrels ( Ictidomys tridecemlineatus ), mole rats ( Heterocephalus glaber ), and bats ( Eptesicus fuscus ) are exceptionally tolerant of low oxygen (i.e. hypoxia). Unfortunately, the basis of this tolerance is not well understood. To elucidate the underlying mechanisms these animals use to match oxygen supply to demand under hypoxic conditions, we exposed animals to progressive reductions in inspired oxygen (21, 12, 9, 7, and 5% O 2 ) at an ambient temperature within their thermoneutral zone, and measured their metabolic, thermoregulatory, and ventilatory responses. Severe hypoxia (5% O 2 ) led to a profound depression in oxygen demand in mole rats (>85%), and bats (>65%), driven by a reduction in metabolism independent of decreases in body temperature. Mole rats and bats met these reduced demands with a combination of reductions in ventilation (45% and 20%, respectively) and increases in the amount of oxygen extracted per breath (40% and 25%, respectively). Unlike mole rats and bats, ground squirrels did not reduce oxygen demand or body temperature in hypoxia; instead they increased oxygen supply through an increase in ventilation (>250%) with no change in the amount of oxygen extracted per breath. Our results suggest that while ground squirrels match oxygen supply to demand in severe hypoxia by a brisk ventilatory response, mole rats and bats do so by reducing metabolic demands, indicating that these species employ divergent strategies to tolerate hypoxia.
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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 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".