CO<sub>2</sub>/pH Chemosensory Signaling in Co-Cultures of Rat Carotid Body Receptors and Petrosal Neurons: Role of ATP and ACh
Bibliographic record
Abstract
The neurotransmitter mechanisms that process acid hypercapnia in the mammalian carotid body (CB) are poorly understood. Using a co-culture model containing rat CB chemoreceptor (type 1 cell) clusters and petrosal neurons (PN), we tested the hypothesis that co-released ACh and ATP was an important mechanism. Sensory transmission from type I clusters to PN in co-culture occurred at chemical synapses via co-release of ATP and ACh because isohydric hypercapnia depolarized and/or increased firing in co-cultured PN, but not in PN cultured alone; PN chemoexcitatory responses were inhibited by decreasing the extracellular Ca(2+):Mg2+ ratio; partial inhibition of these responses occurred during separate perfusion of cholinergic (hexamethonium or mecamylamine) and P2X (suramin) receptor blockers, although inhibition was often complete with both blockers present; and rapid chemoexcitatory responses to hypercapnia were inhibited by acetazolamide (10 microM), an inhibitor of carbonic anhydrase, localized in type I cells. Acidosis (pH = 7.0, 7.2) enhanced the ATP-induced whole cell current in functional PN relative to that at physiologic pH (7.4), suggesting that increased sensitivity of postsynaptic P2X receptors may contribute to acid chemotransmission. Type I cells in CB tissue sections expressed vesicular acetylcholine transporter (VAChT), a cholinergic marker, as revealed by confocal immunofluorescence. Thus co-release of ACh and ATP is an important neurotransmitter mechanism for processing isohydric and acidic hypercapnia in the rat carotid body.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".