Abstract 1489: Mechanisms Underlying Cardioprotective Effects Of Glucagon-like Peptide-1 In Ischemia-reperfusion Injury
Bibliographic record
Abstract
Background : GLP-1 is a member of the gut incretin hormone family, and a GLP-1 receptor agonist (exendin-4) is approved for the treatment of Type-II diabetes. Studies in man post-MI, and in rat and dog models suggest that GLP-1 is cardioprotective. However, the mechanisms underlying the effects of structurally diverse GLP-1 peptides in the heart have not been fully elucidated. Methods & Results: GLP-1(7–36) (i.e. GLP-1), its cleavage product GLP(9–36), and the degradation-resistant GLP-1R agonist exendin-4 were examined in 30 min of global ischemia followed by 40 min of reperfusion (I/R) in Langendorff isolated heart preparations from both wild-type (WT) and GLP-1 receptor knockout (GLP-1R−/−) mice. In WT mice, recovery of left ventricular developed pressure (LVDP) following I/R was higher in GLP-1 pre-infused hearts than in untreated controls (79±9 vs. 42±1%; p<0.01). Pre-treatment with 5 nM but not with 0.3~3 nM exendin-4 also protected the heart from I/R injury. Although pre-infusion of GLP(9–36) induced lower recovery than untreated controls (21.4±1%), post-infusion of either GLP(9–36) or GLP-1 augmented functional recovery to a similar extent (59.1±6% and 53.3±6%). Surprisingly, the cardioprotective effects of pre- and post-treatments with both molecular forms of GLP-1 were detected in studies with GLP-1R−/− hearts (80.1±6% and 55.8±8). Of note, both GLP-1 and GLP(9–36) treatments also demonstrated potent vasodilatory effects, as manifested by increased coronary flow rates in isolated hearts and increased diameters of pre-constricted mesenteric arteries isolated from both WT and GLP-1R−/− mice. The cardioprotective effects on isolated hearts and vasodilatory effects on isolated mesenteric arteries, induced by GLP-1 was blunted by co-treatment with a dipeptidyl peptidase-4 (DPP-4) enzyme inhibitor, that blocked conversion of GLP-1 to GLP(9–36). Increased cGMP release in the coronary effluents was also observed following addition of GLP-1 and GLP(9–36) to hearts isolated from WT and GLP-1R−/− mice. Summary: These data expand the complexity of GLP-1 biology by illustrating that the beneficial effects of GLP-1 in I/R injury are mediated in part by GLP(9–36) via a NO/cGMP-dependent vasodilatory effect that is independent of the known GLP-1R.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.002 |
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".