Branchial Receptors and Cardiorespiratory Reflexes in A Neotropical Fish, The Tambaqui (<i>Colossoma Macropomum</i>)
Bibliographic record
Abstract
This study examined the location and physiological roles of branchial chemoreceptors involved in the cardiorespiratory responses to hypoxia and hypercarbia in a neotropical fish that exhibits aquatic surface respiration, the tambaqui (Colossoma macropomum). Fish were exposed to abrupt progressive environmental hypoxia (18. 6-1.3 kPa water P(O2)) and hypercarbia (water equilibrated with 5 % CO(2) in air, which lowered the water pH from 7.0 to 5.0). They were also subjected to injections of NaCN into the ventral aorta (to stimulate receptors monitoring the blood) and buccal cavity (to stimulate receptors monitoring the respiratory water). All tests were performed before and after selective denervation of branchial branches of cranial nerves IX and X to the gill arches. The data suggest that the O(2) receptors eliciting reflex bradycardia and increases in breathing frequency are situated on all gill arches and sense changes in both the blood and respiratory water and that the O(2) receptors triggering the elevation in systemic vascular resistance, breathing amplitude, swelling of the inferior lip and that induce aquatic surface respiration during hypoxia are extrabranchial, although branchial receptors also contribute to the latter two responses. Hypercarbia also produced bradycardia and increases in breathing frequency, as well as hypertension, and, while the data suggest that there may be receptors uniquely sensitive to changes in CO(2)/pH involved in cardiorespiratory control, this is based on quantitative rather than qualitative differences in receptor responses. These data reveal yet another novel combination for the distribution of cardiorespiratory chemoreceptors in fish from which teleologically satisfying trends have yet to emerge.
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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".