A comparison of no-flow and low-flow ischemia in the rat heart: an energetic study
Bibliographic record
Abstract
Heat production under no-flow ischemia (ISCH) and under hypoperfusion (HYP) conditions was measured in single isovolumetric contractions of perfused rat ventricles at 25°C. Resting heat production (H r ) and resting pressure decreased when the perfusion rate was reduced from 6 to 1.5 mL·min -1 or lower flows (HYP) and by ISCH. Maximal developed pressure (P) decreased to 29% and 20% of control by HYP at 0.8 mL·min 1 and ISCH, respectively. The tension-independent heat (TIH) fraction attributed to Ca 2+ -binding, measured during single contractions, decreased under HYP with an increase in the ratio between the maximum relaxation rate and P (P/P ratio). The TIH fractions (attributed to Ca 2+ binding and Ca 2+ removal processes) decreased under ISCH. The long duration TIH fraction associated with Ca 2+ -dependent mitochondrial activity disappeared at flow rates of 1.5 mL·min 1 or lower. The ratio between the tension-dependent energy release and P was decreased by ISCH but not by HYP, indicating that under ISCH there was an improvement in contractile economy, but this was not modified by HYP. Overall, the results indicate that no-flow and low-flow ischemias are energetically different models. While the contractile failure under HYP seems to be related to a decrease in myofilament Ca 2+ sensitivity, under ISCH it appears to be related to decreased cytosolic Ca 2+ availability combined with a more noticeable effect on a fraction of energy that has been attributed to mitochondrial activity. Furthermore, mechanical and energetic responses of both models (i.e., ISCH and HYP) found in the present work were not the same as those previously observed in severe hypoxia so that all these models should not be used indistinctly.Key words: calorimetry, hypoperfusion, ischemia, muscle economy, tension-dependent heat, tension-independent heat.
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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".