Distribution and role of peripheral arterial chemoreceptors in cardio-respiratory control of the South American rattlesnake (<i>Crotalus durissus</i>)
Bibliographic record
Abstract
Peripheral arterial chemoreceptors monitor the levels of arterial blood gases and adjust ventilation and perfusion to meet metabolic demands. These chemoreceptors are present in all vertebrates studied to date but have not been described fully in reptiles other than turtles. The goals of this study were to (1) identify functional chemosensory areas in the South American rattlesnake (Crotalus durissus), (2) determine the neurochemical content of putative chemosensory cells in these areas and (3) determine the role each area plays in ventilatory and cardiovascular control. To this end, rattlesnakes were instrumented with transonic flow probes, arterial catheters and subcutaneous impedance electrodes to measure shunt fraction, heart rate, blood pressure and ventilation. The catheters were placed at three putative chemosensory sites, the bases of the aortic arch and pulmonary artery, and the carotid bifurcation, for site-specific activation with sodium cyanide (NaCN). These same sites were subsequently examined using immunohistochemical markers for acetylcholine, tyrosine hydroxylase (the rate-limiting enzyme in catecholamine synthesis) and serotonin to identify putative oxygen-sensing cells. All three sites were chemosensory and stimulating each led to cardiovascular (shunt fraction and heart rate) and respiratory adjustments although not in an identical fashion. All three chemosensory areas contained cells positive for serotonin; however, cells positive for vesicular acetylcholine transporter (VAChT) were found only in the aorta and pulmonary artery. We found no labelling for tyrosine hydroxylase at any site.
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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".