Adenosine-A1 Receptors Activation Restores the Suppressed Cardioprotective Effects of Ischemic Preconditioning in Hyperhomocysteinemic Rat Hearts
Bibliographic record
Abstract
BACKGROUND: We have previously shown that the cardioprotective effect of ischemic preconditioning (IPC) is suppressed in hyperhomocysteinemic rat hearts. The present study investigated the effect of 2-chloro-N-cyclopentyladenosine (CCPA), a selective adenosine-A1 receptor agonist, in hyperhomocysteinemia-induced attenuation of the cardioprotective effect of IPC. METHODS: Rats were administered L-methionine (1.7 g/kg/day po) for 8 weeks to produce hyperhomocysteinemia. Isolated Langendorff perfused normal and hyperhomocysteinemic rat hearts were subjected to 30-minute global ischemia, followed by a 120-minute reperfusion. Myocardial infarct size was assessed macroscopically using triphenyltetrazolium chloride staining. Coronary effluent was analyzed for lactate dehydrogenase and CK-MB release to assess the extent of cardiac injury. The oxidative stress in the heart was assessed by measuring thiobarbituric acid reactive substance and reduced form of glutathione. RESULTS: Ischemia and reperfusion (I/R) produced myocardial injury by increasing myocardial infarct size, elevating lactate dehydrogenase and CK-MB release in coronary effluent, decreasing coronary flow rate, and inducing oxidative stress in normal and hyperhomocysteinemic rat hearts. The hyperhomocysteinemic rat hearts showed enhanced I/R-induced myocardial injury with high oxidative stress. The IPC afforded cardioprotection against I/R-induced myocardial injury in normal rat hearts. However, IPC-mediated myocardial protection against I/R injury was abolished in hyperhomocysteinemic rat hearts. Administration of CCPA did not alter the cardioprotective effect of IPC in normal rat hearts, but its administration markedly restored the cardioprotective effect of IPC in hyperhomocysteinemic rat hearts. CONCLUSION: It may be concluded that the activation of adenosine-A1 receptors using CCPA markedly restored the suppressed cardioprotective and infarct size-limiting effects of IPC in hyperhomocysteinemic rat hearts. Thus, the reduced availability of extracellular adenosine and impaired activation of adenosine-A1 receptors may be responsible for abolishing the cardioprotective potential of IPC against I/R-induced myocardial injury in hyperhomocysteinemic rat hearts.
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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) | 0.001 | 0.001 |
| 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".