Inspiratory activation is not required for episodic hypoxia‐induced respiratory long‐term facilitation in postnatal rats
Bibliographic record
Abstract
Episodic hypoxia causes repetitive inspiratory activation that induces a form of respiratory plasticity termed long-term facilitation (LTF). While LTF is a function of the hypoxic exposures and inspiratory activation, their relative importance in evoking LTF is unknown. The aims of this study were to: (1) dissociate the relative roles played by episodic hypoxia and respiratory activation in LTF; and (2) determine whether the magnitude of LTF varies as a function of hypoxic intensity. We did this by examining the effects of episodic hypoxia in postnatal rats (15-25 days old), which unlike adult rats exhibit a prominent hypoxia-induced respiratory depression. We quantified inspiratory phrenic nerve activity generated by the in situ working-heart brainstem before, during and for 60 min after episodic hypoxia. We demonstrate that episodic hypoxia evokes LTF despite the fact that it potently suppresses inspiratory activity during individual hypoxic exposures (P < 0.05). Specifically, we show that after episodic hypoxia (three 5 min periods of 10% O2) respiratory frequency increased to 40 +/- 3.3% above baseline values over the next 60 min (P < 0.001). Continuous hypoxia (15 min of 10% O2) had no lasting effects on respiratory frequency (P > 0.05). To determine if LTF magnitude was affected by hypoxic intensity, the episodic hypoxia protocol was repeated under three different O2 tensions. We demonstrate that the magnitude and time course of LTF depend on hypoxic severity, with more intense hypoxia inducing a more potent degree of LTF. We conclude that inspiratory activation is not required for LTF induction, and that hypoxia per se is the physiological stimulus for eliciting hypoxia-induced respiratory LTF.
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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) | 0.001 | 0.000 |
| 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 | 0.000 | 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".