Ambient Particulate Matter Affects Cardiac Recovery in a Langendorff Ischemia Model
Bibliographic record
Abstract
Exposure to ambient particulate matter (PM) is associated with increased mortality and morbidity among subjects with cardiovascular impairment. We hypothesized that exposure of spontaneously hypertensive (SH) rats to PM impairs the recovery of cardiovascular performance after coronary occlusion and reperfusion-ischemia. SH rats were exposed by intratracheal instillation to saline, standard urban PM (Ottawa dust EHC-93, 10 mg/kg body weight) or endotoxin (lipopolysaccharides LPS, 350 EU/animal) to induce a similar pulmonary inflammation. At 4 h postexposure, hearts were isolated and retrograde perfused in a Langendorff model. The experimental protocol included 35 min of coronary occlusion followed by 120 min of reperfusion, during which left ventricular developing pressure (LDVP), coronary flow (CF), and heart rate (HR) were measured. Baseline LVDP in particle-instilled SH rats was significantly decreased compared to saline-instilled animals. In addition, after ischemia the recovery of LDVP was much slower in rats pretreated with PM or LPS compared to saline instilled rats. The direct effects of the soluble PM fraction and the role of Zn2+ were also tested cardiomyocytes (H9C2 cells). Both particle-free filtrate and Zn2+ inhibited ATP or ionophore-stimulated calcium influx in cardiomyocytes. This inhibitory effect was related to an effect on calcium channels, as shown with Nifedipine. This study provides evidence that exposure to instillation of PM has reversible acute effects on the recovery of cardiac physiological parameters after ischemia. The effect may be caused by a direct action of soluble metals on calcium homeostasis in heart, but pulmonary inflammation may also play a significant role.
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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) | 0.000 | 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 | 0.001 |
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; both teacher heads agree on what is shown here.
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".