Mechanisms for pesticide-induced cardiotoxicity in fish: An electrophysiological study using the zebrafish (Danio rerio) as a model
Bibliographic record
Abstract
Fish kills are a common phenomenon in Prince Edward Island (Canada) and their cause often remains unexplained. I hypothesized that fish exposure to selected environmental toxicants leads to increased mortality and morbidity by depressing cardiac function, precipitated by suppression of cardiac electrical activity and rhythm disturbances. These rhythm disturbances could result from toxicant-induced changes in the function of specific cardiac ion channels. Recently, the zebrafish heart has been shown to hold promise as a suitable model to study cardiac cellular electrophysiology. The purpose of the present study was to\nevaluate the effects of selected environmental toxicants on cardiac action potential morphology. More specifically, the present work focused on evaluating the effects on atrial action potential in adult zebrafish of: 1) acetylcholine (1-10 μM); 2) a documented acetylcholinesterase inhibitor, physostigmine (50 μM); 3) pesticides with acetylcholinesterase inhibition properties that are commonly used in Prince Edward Island (mancozeb and phorate). Zebrafish hearts were isolated under anesthesia and\naction potentials were recorded in vitro using a standard single microelectrode technique. Action potential morphology was then assessed by measuring parameters including action potential duration (APD) and action potential amplitude (APA). Results revealed that in vitro exposures to high concentrations of acetylcholine\nand physostigmine led to suppression of cardiac electrical activity by significantly reducing APD and APA, a phenomenon known as cholinergic non-excitability. Experiments evaluating the effects of commercial pesticides (mancozeb and phorate) did not reveal similar effects. This study supports the possibility that environmental toxicants containing acetylcholinesterase inhibitors may participate in fish kills by suppressing cardiac electrical activity. However, the specific pesticides mancozeb and phorate did not demonstrate such dramatic cardiotoxic effects, even at high concentrations.
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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".