l-Arginine administration recovers sarcoplasmic reticulum function in ischemic reperfused hearts by preventing calpain activation
Bibliographic record
Abstract
OBJECTIVE: Earlier studies have shown that impaired cardiac contractility in ischemia reperfusion (IR) is associated with alterations in sarcoplasmic reticulum (SR) function. Impaired release of nitric oxide (NO) has been reported during IR, while administration of NO donors, such as L-arginine (LA), has been shown to improve cardiac performance in IR hearts. We therefore investigated the mechanisms underlying the recovery of contractile function in IR hearts treated with LA. METHODS: Isolated rat hearts subjected to 30 min of global ischemia were reperfused for 60 min. The effects of LA on cardiac performance, SR function and its regulation were examined. RESULTS: IR-induced impairment in cardiac performance was associated with a reduction in SR function and its regulation. IR caused an increase in calpain activity and a decrease in the sarcolemmal and SR nitric oxide synthase (NOS) isoform protein content as well as cytosolic NO levels. Administration of LA prevented contractile dysfunction in IR hearts, which was associated with a recovery of SR function and SR regulation by protein phosphorylation. This was consistent with a recovery in protein levels of major SR Ca2+-cycling and Ca2+-regulatory proteins. LA treatment attenuated an increase in calpain activity, possibly by nitrosylation of calpain, and increased cytosolic NO levels and SR NOS protein content in IR hearts. DISCUSSION: These results suggest that LA administration improved cardiac contractility by preventing alterations in SR Ca2+ handling and calpain activation in IR 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 | 0.005 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| 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".