Reversal of cardiac dysfunction and subcellular alterations by metoprolol in heart failure due to myocardial infarction
Bibliographic record
Abstract
In order to examine the reversibility of heart failure due to myocardial infarction (MI) by β-adrenoceptor blockade, 12 weeks infarcted rats were treated with or without metoprolol (50 mg/kg/day) for 8 weeks. The depressed left ventricular (LV) systolic pressure, positive and negative rates of changes in pressure development, ejection fraction, fractional shortening and cardiac output, as well as increased LV end-diastolic pressure in 20 weeks MI animals were partially reversed by metoprolol. MI-induced decreases in septum (systolic) thickness as well as increase in LV posterior wall thickness and LV internal diameter were partially or fully reversible by metoprolol. Treatment of MI animals with metoprolol partially reversed the elevated levels of plasma norepinephrine and dopamine without affecting the elevated levels of epinephrine. Although sarcoplasmic reticular (SR) Ca(2+)-uptake, as well as protein content for SR Ca(2+)-pump and phospholamban, were reduced in the infarcted hearts; these changes were partially reversible with metoprolol. Depressed myofibrillar Ca(2+)-stimulated ATPase activity, as well as mRNA levels for SR Ca(2+)-pump, phospholamban and α-myosin heavy chain, were unaffected whereas increased mRNA level for β-myosin heavy chain was partially reversed by metoprolol. The results suggest that partial improvement of cardiac performance by β-adrenoceptor blockade at advanced stages of heart failure may be due to partial reversal of changes in SR Ca(2+)-pump function whereas partial to complete reverse cardiac remodeling may be due to partial reduction in the elevated levels of plasma catecholamines.
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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) | 0.000 | 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) | 0.001 | 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".