N-acetylcysteine Prevents Nitrosative Stress-Associated Depression of Blood Pressure and Heart Rate in Streptozotocin Diabetic Rats
Bibliographic record
Abstract
Previous studies have indicated that cardiovascular abnormalities such as depressed blood pressure and heart rate occur in streptozotocin (STZ) diabetic rats. Chronic diabetes, which is associated with increased expression of inducible nitric oxide synthase (iNOS) and oxidative stress, may produce peroxynitrite/nitrotyrosine and cause nitrosative stress. We hypothesized that nitrosative stress causes cardiovascular depression in STZ diabetic rats and therefore can be corrected by reducing its formation. Control and STZ diabetic rats were treated orally for 9 weeks with N-acetylcysteine (NAC), an antioxidant and inhibitor of iNOS. At termination, the mean arterial blood pressure (MABP) and heart rate (HR) were measured in conscious rats. Nitrotyrosine and endothelial nitric oxide synthase (eNOS) and iNOS expression were assessed in the heart and mesenteric arteries by immunohistochemistry and Western blot experiments. Untreated diabetic rats showed depressed MABP and HR that was prevented by treatment with NAC. In untreated diabetic rats, levels of 15-F(2t)-isoprostane, an indicator of lipid peroxidation increased, whereas plasma nitric oxide and antioxidant concentrations decreased. Furthermore, decreased eNOS and increased iNOS expression were associated with elevated nitrosative stress in blood vessel and heart tissue of untreated diabetic rats. N-acetylcysteine treatment of diabetic rats not only restored the antioxidant capacity but also reduced the expression of iNOS and nitrotyrosine and normalized the expression of eNOS to that of control rats in heart and superior mesenteric arteries. The results suggest that nitrosative stress depress MABP and HR following diabetes. Further studies are required to elucidate the mechanisms involved in nitrosative stress mediated depression of blood pressure and heart rate.
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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 | 0.000 |
| 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) | 0.000 | 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".