Mild hypoxia as therapy for post-ischemic mitochondrial injury
Bibliographic record
Abstract
Introduction: Mitochondrial injury occurs following cellular ischemia in the setting of myocardial infarction, stroke, and cardiac arrest (CA). Effective strategies for reducing injury are limited. Hypoxia has shown benefit in reversing mitochondrial mediated neurodegenerative disease but is little studied in the setting of post-ischemic injury and is regarded as potentially harmful. In this study, we investigated the effects of mild hypoxia on global post-ischemic injury following CA. We hypothesized that brief mild hypoxia following CA would improve mitochondrial function resulting in improved cellular metabolism and physiological recovery. Methods and Results: Anesthetized C57BL6 mice underwent brief asystolic CA (12 min) followed bycardiopulmonary resuscitation(CPR). One hour following successful CPR, mice were randomized to receive a brief episode (6 hours) of normoxia (21% O2) or hypoxia (10% O2) in an environmental chamber. Post intervention, the mice were returned to room air (21% O2). Mild hypoxia improved cardiac mitochondrial complex 1 respiration in the heart by 28% and ATP-related oxygen consumption by 49% (n=3, P<0.05 vs normoxia, respectively) compared to normoxia treated mice. Hypoxia was further associated with improved glucose oxidation in heart as evidenced by decreases in pyruvate dehydrogenase kinase 4 (PDK4) gene and protein expression (n=4, P<0.05 vs normoxia, respectively) as well as decreases in pyruvate dehydrogenase phosphorylation (n=4, P<0.05, respectively) in heart. Hypoxia decreased lactate dehydrogenase (LDH) expression and lactate concentration in heart compared to normoxia treated controls (n=4, P<0.05 vs normoxia, respectively). ROS production in heart by 20% (n=6, P<0.05) was also decreased by mild hypoxia when compared to normoxia post CA. These changes were associated with improved recovery of myocardial function, neurological recovery, and 10-day survival following CA (n=13, P<0.05 vs normoxia, respectively). Conclusion: Brief mild hypoxia treatment following global ischemic injury paradoxically improved recovery of myocardial mitochondrial respiration and metabolism and was associated with improved physiological recovery and survival. Post-ischemia hypoxia is a potential therapeutic strategy for mitochondrial ischemic injury and requires further study. No financial disclosures. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".