Abstract 300: Ischemia and Reperfusion Injury Following Cardioplegic Arrest is Attenuated by Age and Testosterone Deficiency in Male but Not Female Mice
Bibliographic record
Abstract
Cardiovascular disease increases with age in both sexes and treatment can require cardiac surgery, where the heart is pre-treated with a protective cardioplegic solution before exposure to ischemia and reperfusion (I/R). While endogenous estrogen is thought to be beneficial in I/R, the role of testosterone in cardioprotection is not well understood and whether age modifies responses to I/R is unclear. We investigated sex- and age-specific differences in I/R injury in hearts pre-treated with a clinically relevant cardioplegic solution. Hearts were isolated from adult (6-9 mos) and old (22-28 mos) C57BL/6 mice of both sexes (n=27). They were Langendorff-perfused with Krebs-Henseleit buffer (15 min; 37°C), followed by St. Thomas’2 cardioplegia (6 min; 6-7°C). This was followed by 90 min of global ischemia (room temperature) and 30 min of reperfusion (37°C). Hearts were then perfused with triphenyltetrazolium chloride to quantify infarct area. The role of testosterone was investigated in gonadectomized (GDX; 6-9 mos) male mice and serum testosterone was measured with an ELISA. Functional recovery in reperfusion was significantly better in old males than in adult males. Left ventricular developed pressure (LVDP) recovered to 67.3 ± 7.4% in old compared to 31.6 ± 12.3% in adult male hearts (p<0.05). Similar results were seen for rates of pressure development (+dP/dt; p<0.05) and decay (-dP/dt; p<0.05). Also, infarct areas were markedly smaller in old male hearts (15.5 ± 1.8%) than in younger hearts (48.1 ± 7.7%; p<0.05). By contrast, hearts from adult and old females exhibited a similar degree of post-ischemic functional recovery and showed no age-dependent difference in infarct size. Serum testosterone levels declined with age in males but were low regardless of age in females, which suggested a potential benefit of low testosterone. In support of this, hearts from GDX males exhibited much better recovery of LVDP in reperfusion when compared to hearts from intact males (values were 64.8 ± 7.7% vs. 29.9 ± 12.3%; p<0.05). GDX hearts also had smaller infarcts than hearts from intact males (p<0.05). These results suggest that low testosterone levels may be protective against I/R injury following cardioplegic arrest in the setting of aging, especially in old males.
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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 | 0.001 | 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 | 0.001 |
| 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 teacher head, 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".