The antioxidant effects of a novel iron chelator salicylaldehyde isonicotinoyl hydrazone in the prevention of H2O2 injury in adult cardiomyocytes
Bibliographic record
Abstract
OBJECTIVE: This study was designed to investigate the cardioprotective effect of the novel lipophilic iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH) against the oxidative stress exerted by H(2)O(2) through the production of OH radical via the Fenton reaction and to compare them with those of the hydrophilic iron chelator deferoxamine (DFO) and the Na(+)/H(+) exchange inhibitor methylisobutyl amiloride (MIA). METHODS: We used long-term cultures of spontaneously beating adult guinea-pig ventricular cardiomyocytes developed and characterized previously in our laboratory. We assessed their contractile activity by video-recording as well as the underlying Ca(i)(2+) transients by Fura 2 fluorescence. In some experiments we also recorded these functional parameters, plus the electrical activity (action potentials) in response to electrical stimulation via suction pipettes, in individual freshly isolated myocytes. RESULTS: Exposure of the regularly and synchronously beating cultured cardiomyocytes to 100 microM H(2)O(2) initially caused a substantial prolongation of Ca(i)(2+) transients accompanied by an irregular contractile activity, then in contractile arrest and a severalfold increase in cytosolic [Ca(2+)] that occurred, within 30 min of H(2)O(2) application. Similar effects were also observed using freshly isolated cardiomyocytes. The latter effects were first accompanied by significant prolongation of the action potential duration (APD) with superimposed early afterdepolarizations followed by a second phase with a very fast decrease in APD, contractions, as well as Ca(i)(2+) transients and a third phase of inexcitability, contractile arrest, increased cytoplasmic [Ca(2+)] and a final contracture. All these effects were irreversible in both types of preparations but they could be fully prevented by a 15-min preincubation with 200 microM SIH. Similar protective effects were observed with DFO, but in this case a much higher concentration had to be used (1 mM) and much longer (2 h) preincubation was needed. By contrast, 5 microM MIA failed to fully protect the cardiomyocytes, although a significant delay (10 min) of the effects of H(2)O(2) was observed. CONCLUSIONS: The data indicate that SIH provides a very powerful and very fast protection against the oxidative stress exerted by H(2)O(2) presumably via the iron-mediated Fenton reaction producing hydroxyl radical (OH), whereas the protective effect of DFO is hindred by its very slow and rather limited intracellular entry, and the protection that MIA exerts via the inhibition of Na(+)/H(+) exchange against H(2)O(2) much less effective.
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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) | 0.000 | 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 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".