Maintenance of resting tension in the American eel (Anguilla rostrata L.) heart is dependent upon exogenous fuel and the sarcoplasmic reticulum
Bibliographic record
Abstract
The relationship between extracellular glucose and management of cell Ca(2+) in the heart of the American eel (Anguilla rostrata) was indirectly assessed by monitoring the performance of isolated ventricular strips at 20 degrees C. Twitch force increased in ventricular strips under specific conditions of 30 bpm pacing and an extracellular Ca(2+) challenge from 1.5 to 9.5 mM. The response was independent of any exogenous metabolic fuel in the medium. Resting tension was maintained when glucose was available, but in the absence of a metabolic fuel, resting tension increased in response to the increase in extracellular Ca(2+) level. When ventricular strips were treated with iodoacetate to inhibit glycolysis, a Ca(2+) challenge resulted in a decrease in twitch force in association with an approximately equivalent increase in resting tension even in the presence of exogenous glucose. However, when pyruvate (5 mM) was substituted as a metabolic fuel, twitch force increased as a function of extracellular Ca(2+), and resting tension was maintained in the presence of iodoacetate. Therefore, there is a need for an extracellular fuel but not a specific metabolic requirement for glucose to maintain the performance characteristics, which are presumably related to the management of intracellular Ca(2+) levels. Ventricular strips were treated with ryanodine to inhibit Ca(2+) release and uptake by the sarcoplasmic reticulum (SR). Ryanodine treatment impaired postrest potentiation at high extracellular Ca(2+) levels. In the presence of ryanodine, the protective effect of glucose on the increase in resting tension in the face of an extracellular Ca(2+) challenge was eliminated. Considered together, the results reveal that the heart of the American eel has a requirement for an extracellular fuel to manage intracellular Ca(2+) at high Ca(2+) loads, and that the SR plays a role in the beat-to-beat regulation of Ca(2+) at a frequency of 30 bpm, high Ca(2+) load, and 20 degrees C.
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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 | 0.001 |
| 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 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".