Preconditioning prevents alterations in cardiac SR gene expression due to ischemia-reperfusion
Bibliographic record
Abstract
We have previously shown that ischemic preconditioning (IP) improves cardiac performance and sarcoplasmic reticulum (SR) function in hearts subjected to ischemia-reperfusion (I/R). In this study, we examined the effect of IP on I/R-induced changes in gene expression for SR proteins such as the Ca(2+) release channel, Ca(2+) pump ATPase, phospholamban, and calsequestrin in the isolated rat heart. Normal isolated rat hearts exposed to three brief cycles of IP (5-min ischemia and 5-min reperfusion) exhibited a significant decrease in the transcript levels of SR genes. Nonpreconditioned I/R hearts when subjected to 30-min ischemia and 30-min reperfusion showed a marked decrease in mRNA levels for the SR proteins compared with normal hearts; this decrease was attenuated by preconditioning. Although hearts subjected to Ca(2+) paradox (CP) have been shown to exhibit intracellular Ca(2+) overload and SR dysfunction like those in I/R hearts, virtually nothing is known regarding the effect of CP on cardiac SR gene expression. Accordingly, CP (5-min Ca(2+)-free perfusion and 30-min reperfusion with normal medium) was observed to produce dramatic changes in SR gene expression, and the heart failed to contract; these alterations were attenuated by IP. Our results show that 1) both I/R and CP depress SR gene expression in the normal heart, 2) IP attenuates I/R- and CP-induced depression in cardiac function and SR gene expression, and 3) intracellular Ca(2+) overload may play a role in depressing SR gene expression in both I/R and CP hearts.
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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) | 0.001 | 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) | 0.000 | 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".