Catecholamines modulate the hypoxic ventilatory response of larval zebrafish (<i>Danio rerio</i>)
Bibliographic record
Abstract
The hypoxic ventilatory response (HVR) in fish is an important reflex that aids O2 uptake when low environmental O2 levels constrain diffusion. In developing zebrafish (Danio rerio), the acute HVR is multiphasic, consisting of a rapid increase in ventilation frequency (fV) during hypoxia onset, followed by a decline to a stable plateau phase above fV under normoxic conditions. In this study, we examined the potential role of catecholamines in contributing to each of these phases of the dynamic HVR in zebrafish larvae. We showed that adrenaline elicits a dose-dependent β-adrenoreceptor (AR)-mediated increase in fV that does not require expression of β1-ARs, as the hyperventilatory response to β-AR stimulation was unaltered in adrb1-/- mutants, generated by CRISPR/Cas9 knockout. In response to hypoxia and propranolol co-treatment, the magnitude of the rapidly occurring peak increase in fV during hypoxia onset was attenuated (112±14 breaths min-1 without propranolol to 68±17 breaths min-1 with propranolol), whereas the increased fV during the stable phase of the HVR was prevented in both wild type and adrb1-/- mutants. Thus, β1-AR is not required for the HVR and other β-ARs, although not required for initiation of the HVR, are involved in setting the maximal increase in fV and in maintaining hyperventilation during continued hypoxia. This adrenergic modulation of the HVR may arise from centrally released catecholamines because adrenaline exposure failed to activate (based on intracellular Ca2+ levels) cranial nerves IX and X, which transmit O2 signals from the pharyngeal arch to the central nervous system.
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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".