Noradrenergic modulation of respiratory motor output during tadpole development: role of α‐adrenoceptors
Bibliographic record
Abstract
Lung ventilation appears progressively during bullfrog development; however, little is known about the neural mechanisms contributing to the emergence of air breathing in this species. We used an in vitro brainstem preparation from Rana catesbeiana to test the hypothesis that noradrenergic modulation of respiratory related motor output facilitates fictive lung ventilation during development. We first compared the effects of noradrenaline (NA) bath application (conc. = 0.02–10 μM) onto brainstem preparations from pre- and post-metamorphic tadpoles (TK stages VII-XI and XVIII-XXIII, respectively) and adult bullfrogs. NA bath application exerted stage-dependent effects on fictive lung burst frequency which increased in pre-metamorphic tadpoles but decreased in post-metamorphic tadpoles and adult bullfrogs. Conversely, NA bath application increased fictive gill ventilation frequency in both tadpole groups. In a second series of experiments, the α1 and α2-adrenoceptor agonists phenylephrine (Phe) and clonidine (Clo) were applied onto preparations (conc. = 25–200 μM) to determine whether these receptors mediate these changes in fictive lung and gill ventilation frequency. Data show that, for each stage, α1-adrenoceptor activation with Phe mimicked well the effects of NA application on lung burst frequency; however, both drugs decreased fictive gill ventilation frequency suggesting that β-adrenoceptors may mediate this effect. We conclude that noradrenergic modulation of lung ventilation changes during development but does not facilitate lung ventilation in more mature animals. Supported by the Natural Sciences and Engineering Research Council 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 | 0.000 |
| 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) | 0.001 | 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".