Measurements of Electrophysiological Effects of Components of Acute Ischemia in Langendorff‐Perfused Rat Hearts Using Voltage‐Sensitive Dye Mapping
Bibliographic record
Abstract
INTRODUCTION: This study was carried out to evaluate optical mapping in the presence of cytochalasin-D as a method for measuring electrophysiological responses in general, and in particular the responses to acute ischemia in the Langendorff-perfused rat heart. Cytochalasin-D is commonly used to reduce contraction for the purpose of suppressing motion artifacts in voltage-sensitive dye recordings of cardiac membrane potential. METHODS AND RESULTS: Observations using optical mapping were complemented by recordings of the surface electrogram to provide information independent of the optical measurements. Perfusion of Langendorff-perfused rat hearts with 3 microM cytochalasin-D resulted in a 24% prolongation of the QT interval of surface electrograms indicating that cytochalasin-D prolongs the rat ventricular action potential. Individual components of the electrophysiological response to acute ischemia were globally induced as follows: (1) opening of K(ATP) channels was induced by perfusion of 2 micro M P-1,075, (2) accumulation of extracellular K(+) was simulated by increasing perfusate [K(+)] to 12 mM, and (3) acidosis was simulated by reducing perfusate pH to 6.5. The responses to these interventions could be reliably documented using optical recordings, as well as from surface electrograms. Whole-cell patch clamp measurements on isolated rat ventricular myocytes indicate that cytochalasin-D produces an approximately 2.5-fold increase in P-1,075-induced I(K,ATP). CONCLUSION: These results provide the necessary background information for interpreting electrophysiological measurements during acute ischemia in the presence of cytochalasin-D.
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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) | 0.001 | 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".