Catecholamine secretion in trout chromaffin cells experiencing nicotinic receptor desensitization is maintained by non-cholinergic neurotransmission
Bibliographic record
Abstract
The goal of the present study was to assess the catecholamine secretory capabilities of rainbow trout Oncorhynchus mykiss chromaffin cells experiencing desensitization of the nicotinic receptor. It was hypothesized that the potential to secrete catecholamines could be maintained under conditions of nicotinic receptor desensitization owing to activation of non-cholinergic release pathways. An in situ model for chromaffin cell nicotinic receptor desensitization was developed by perfusing a posterior cardinal vein preparation with saline containing 10(-5) mol l(-1) nicotine. Under such conditions of desensitization, the chromaffin cells were largely unresponsive to high-frequency (20 Hz) electrical stimulation; the minimal remaining secretory response was abolished by addition of the nicotinic receptor antagonist hexamethonium (10(-3) mol l(-1)). In marked contrast, however, the capacity to secrete catecholamines in response to low-frequency (1 Hz) electrical stimulation was unaffected by nicotinic receptor desensitization or by cholinergic receptor blockade (hexamethonium plus atropine). In preparations experiencing nicotinic receptor desensitization, the stimulatory effect of low-frequency (1 Hz) stimulation on catecholamine secretion was reduced by 43% in the presence of the VPAC receptor antagonist, VIP(6-28). The stimulatory effect of high-frequency (20 Hz) stimulation was unaffected by VIP(6-28). Catecholamine secretion evoked by cod VIP (10(-11) mol kg(-1)) and homologous angiotensin II ([Asn(1), Val(5)] Ang II; 5 x 10(-7) mol kg(-1)) was markedly enhanced (107 and 97%, respectively) in desensitized preparations. However, the secretory response to the muscarinic receptor agonist methylcholine (1 x 10(-3) mol kg(-1)) was unchanged by desensitization. The results of this study demonstrate that exploitation of non-cholinergic mechanisms, including peptidergic pathways activated during low-frequency neuronal stimulation, is a potential strategy whereby catecholamine secretion from trout chromaffin cells can be maintained during periods of nicotinic receptor desensitization.
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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 | 0.000 |
| 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) | 0.000 | 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".