Mitochondrial role in ischemia–reperfusion of rat hearts exposed to high-K<sup>+</sup>cardioplegia and clonazepam: energetic and contractile consequences
Bibliographic record
Abstract
The role of the mitochondrial Na/Ca-exchanger (mNCX) in hearts exposed to ischemia-reperfusion (I/R) and pretreated with cardioplegia (CPG) was studied from a mechano-calorimetric approach. No-flow ischemia (ISCH) and reperfusion (REP) were developed in isolated rat hearts pretreated with 10 micromol/L clonazepam (CLZP), an inhibitor of the mNCX, and (or) a high K+ - low Ca2+ solution (CPG). Left ventricular end diastolic pressure (LVEDP), pressure development during beats (P), and the steady heat release (Ht) were continuously measured and muscle contents of ATP and PCr were analyzed at the end of REP. During REP, Ht increased more than P, reducing muscle economy (P/Ht) and the ATP content. CPG induced an increase in P recovery during REP (to 90% +/- 10% of preISCH) with respect to nonpretreated hearts (control, C, to 64% +/- 10%, p < 0.05). In contrast, CLZP reduced P recovery of CPG-hearts (50% +/- 6.4%, p < 0.05) and increased LVEDP in C hearts. To evaluate effects on sarcoplasmic reticulum (SR) function, ischemic hearts were reperfused with 10 mmol/L caffeine -36 mmol/L Na (C - caff - low Na). It increased LVEDP, which afterwards slowly relaxed, whereas Ht increased (by about 6.5 mW/g). CLZP sped up the relaxation with higher DeltaHt, C - caff - low Na produced higher contracture and lower Ht in perfused than in ischemic hearts. Values of DeltaHt were compared with reported fluxes of Ca2+-transporters, suggesting that mitochondria may be in part responsible for the DeltaHt during C - caff - low Na REP. Results suggest that ISCH-REP reduced the SR store for the recovery of contractility, but induced Ca2+ movement from the mitochondria to the SR stores. Also, mitochondria and SR are able to remove cytosolic Ca2+ during overloads (as under caffeine), through the mNCX and the uniporter. CPG increases Ca2+ cycling from mitochondria to the SR, which contributes to the higher recovery of P. In contrast, CLZP produces a deleterious effect on ISCH-REP associated with higher heat release and reduced resynthesis of high energy phosphates, which suggests the induction of mitochondrial Ca cycling and uncoupling.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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".