Nitric oxide mediates metabolism as well as respiratory and cardiac responses to hypoxia in the snail <i>lymnaea stagnalis</i>
Bibliographic record
Abstract
Lymnaea stagnalis were exposed to hypoxic and chemical challenges while ventilation, heart rate and metabolism were monitored. Hypoxia increased ventilatory behavior, but this response was eliminated by immersion in 0.75 mM nitric oxide synthase (NOS) inhibitor, 7-nitroindazole (7 NI). 7 NI also suppressed ventilatory behavior under normoxia. 10.0 mM L-arginine (ARG, the NOS substrate) increased ventilatory behavior under normoxia, but dampened the hypoxic response. The heart-rate response to NOS inhibition exhibited dose-dependent contradictory characteristics. Under both normoxia and hypoxia 0.25 mM 7 NI increased heart rate, while 0.75 mM 7 NI suppressed it. The effect of 0.50 mM 7 NI depended on whether normoxia or hypoxia was coincident; under normoxia 0.50 mM 7 NI increased heart rate, while under hypoxia this concentration suppressed heart rate. Exposure to ARG did not elicit dose-dependent contradictory responses. Heart rate increased when treated with 10.0 mM ARG under normoxia and hypoxia, while 1.0 mM ARG increased heart rate only under hypoxia. Metabolic responses to NOS inhibition also exhibited dose-dependent contradictory changes. V.O2 decreased over 60% in response to 0.75 mM 7 NI, and baseline V.O2 was restored when exposure ceased. In contrast, 0.25 mM 7 NI increased V.O2 10%, and the increase continued after exposure ceased. 0.50 mM 7 NI decreased V.O2 40%, but V.O2 increased when exposure ceased. ARG had only the effect of increasing V.O2, and only at 10.0 mM concentration. Based on these results and on NO's known role as a neuromodulator, we conclude that the cardio-respiratory responses to hypoxia are, in part, mediated by NO.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".