Mechanisms of ischemic preconditioning effects on Ca<sup>2+</sup>paradox-induced changes in heart
Bibliographic record
Abstract
The effects of ischemic preconditioning (IP) on changes in cardiac performance and sarcoplasmic reticulum (SR) function due to Ca2+paradox were investigated. Isolated perfused hearts were subjected to IP (three cycles of 3-min ischemia and 3-min reperfusion) followed by Ca2+-free perfusion and reperfusion (Ca2+paradox). Perfusion of hearts with Ca2+-free medium for 5 min followed by reperfusion with Ca2+-containing medium for 30 min resulted in a dramatic decrease in the left ventricular (LV) developed pressure and a marked increase in LV end-diastolic pressure. Alterations in cardiac contractile activity due to Ca2+paradox were associated with depressed SR Ca2+-uptake, Ca2+-pump ATPase, and Ca2+-release activities as well as decreased SR protein contents for Ca2+-pump and Ca2+channels. All these changes due to Ca2+paradox were significantly prevented in hearts subjected to IP. The protective effects of IP on Ca2+paradox changes in cardiac contractile activity as well as SR Ca2+-pump and Ca2+-release activities were lost when the hearts were treated with 8-( p-sulfophenyl)-theophylline, an adenosine receptor antagonist; KN-93, a specific Ca2+/calmodulin-dependent protein kinase II (CaMK II) inhibitor; or chelerythrine chloride, a protein kinase C (PKC) inhibitor. These results indicate that IP rendered cardioprotection by preventing a depression in SR function in Ca2+paradox hearts. Furthermore, these beneficial effects of IP may partly be mediated by adenosine receptors, PKC, and CaMK II.
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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) | 0.001 | 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) | 0.002 | 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".