Contribution of Na+/Ca2+ Exchange Current to the Formation of Delayed Afterdepolarizations in Intact Rat Ventricular Muscle
Bibliographic record
Abstract
AIM: To evaluate the role of the Na+-Ca2+ exchange current in the induction of arrhythmias during Ca2+ waves, we investigated the relationship between Ca2+ waves and delayed afterdepolarizations (DADs) and further investigated the effect of KB-R7943, an Na+-Ca2+ exchange inhibitor, on such relationship in multicellular muscle. METHODS: Force, sarcomere length, membrane potential, and [Ca2+]i dynamics were measured in 32 ventricular trabeculae from rat hearts. After the induction of Ca2+ waves by trains of electrical stimuli (400, 500, or 600 ms intervals) for 7.5 seconds, 23 Ca2+ waves in the absence of KB-R7943 and cilnidipine ([Ca2+]o = 2.3 +/- 0.2 mmol/L), 11 Ca2+ waves in the presence of 10 micromol/L KB-R7943 ([Ca2+]o = 2.5 +/- 0.5 mmol/L), and 8 Ca2+ waves in the presence of 1 micromol/L cilnidipine ([Ca]o = 4.1 +/- 0.3 mmol/L) were measured at a sarcomere length of 2.1 microm (23.9 +/- 0.8 degrees C). RESULTS: The amplitude of DADs correlated with the velocity (r = 0.90) and the amplitude (r = 0.90) of Ca2+ waves. The amplitude of DADs was significantly decreased to approximately 40% of the initial value by 10 micromol/L KB-R7943. CONCLUSIONS: These results suggest that the velocity and the amplitude of Ca2+ waves determine the formation of DADs principally through the activation of the Na+-Ca2+ exchange current, thereby inducing triggered arrhythmias in multicellular ventricular muscle.
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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 | 0.001 |
| 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".