Effects of Na<sup>+</sup>/Ca<sup>2+</sup> exchanger downregulation on contractility and [Ca<sup>2+</sup>]<sub>i</sub> transients in adult rat myocytes
Bibliographic record
Abstract
Postmyocardial infarction (MI) rat myocytes demonstrated depressed Na(+)/Ca(2+) exchange (NCX1) activity, altered contractility, and intracellular Ca(2+) concentration ([Ca(2+)](i)) transients. We investigated whether NCX1 downregulation in normal myocytes resulted in contractility changes observed in MI myocytes. Myocytes infected with adenovirus expressing antisense (AS) oligonucleotides to NCX1 had 30% less NCX1 at 3 days and 66% less NCX1 at 6 days. The half-time of relaxation from caffeine-induced contracture was twice as long in ASNCX1 myocytes. Sarcoplasmic reticulum (SR) Ca(2+)-ATPase abundance, SR Ca(2+) uptake, resting membrane potential, action potential amplitude and duration, L-type Ca(2+) current density and cell size were not affected by ASNCX1 treatment. At extracellular Ca(2+) concentration ([Ca(2+)](o)) of 5 mM, ASNCX1 myocytes had significantly lower contraction and [Ca(2+)](i) transient amplitudes and SR Ca(2+) contents than control myocytes. At 0.6 mM [Ca(2+)](o), contraction and [Ca(2+)](i) transient amplitudes and SR Ca(2+) contents were significantly higher in ASNCX1 myocytes. At 1.8 mM [Ca(2+)](o), contraction and [Ca(2+)](i) transient amplitudes were not different between control and ASNCX1 myocytes. This pattern of contractile and [Ca(2+)](i) transient abnormalities in ASNCX1 myocytes mimics that observed in rat MI myocytes. We conclude that downregulation of NCX1 in adult rat myocytes resulted in decreases in both Ca(2+) influx and efflux during a twitch. We suggest that depressed NCX1 activity may partly account for the contractile abnormalities after MI.
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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) | 0.000 | 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) | 0.001 | 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".