Specific electromechanical responses of cardiomyocytes to individual and combined components of ischemia
Bibliographic record
Abstract
The main factors of myocardial ischemia are hypoxia, substrate deprivation, acidosis, and high extracellular potassium concentration ([K+]e), but the influence of each of these factors has not yet been evaluated in a cardiomyocyte (CM) culture system. Electromechanical responses to the individual and combined components of ischemia were studied in CM cultured from newborn rat ventricles. Action potentials (APs) were recorded using glass microelectrodes and contractions were monitored photometrically. Glucose-free hypoxia initially reduced AP duration, amplitude, and rate and altered excitation-contraction coupling, but AP upstroke velocity (Vmax) remained unaffected. Early afterdepolarizations appeared, leading to bursts of high-rate triggered impulses before the complete arrest of electromechanical activity after 120 min. Acidosis reduced Vmax whereas AP amplitude and rate were moderately decreased. Combining acidosis and substrate-free hypoxia also decreased Vmax but attenuated the effects of substrate-free hypoxia on APs and delayed the cessation of the electrical activity (180 min). Raising [K+]e reduced the maximal diastolic potential and Vmax. Total ischemia (substrate deletion, hypoxia, acidosis, and high [K+]e) decreased AP amplitude and Vmax without changing AP duration. Moreover, delayed afterdepolarizations appeared, initiating triggered activity. Ultimately, 120 min of total ischemia blocked APs and contractions. To conclude, glucose-free hypoxia caused severe functional defects, acidosis delayed the changes induced by substrate-free hypoxia, and total ischemia induced specific dysfunctions differing from those caused by the former conditions. Heart-cell cultures thus represent a valuable tool to scrutinize the individual and combined components of ischemia on CMs.
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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 | 0.000 |
| 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".