Tempol selectively attenuates angiotensin II evoked vasoconstrictor responses in spontaneously hypertensive rats
Bibliographic record
Abstract
OBJECTIVE: To assess whether superoxide anions mediate vasoconstrictor responses to agonists in blood vessels of spontaneously hypertensive rats (SHRs). METHODS: The effect of the superoxide dismutase mimetic, 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol), on responses to angiotensin II (Ang II), endothelin-1, phenylephrine and potassium chloride was determined in aortic rings and perfused mesenteric vascular beds (MVB) of adult male rats of the Sprague-Dawley, Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) strains. The effect of tempol on Ang II-evoked superoxide production was assessed in aortic rings. RESULTS: There were no differences in the maximum tension (Emax) attained in response to agonists, but the negative logarithm of the concentration required to produce 50% of the maximal response (EC50) for Ang II was lower (P < 0.05) in aortic rings of SHRs. In the MVBs of SHRs, the Emax but not the EC50 values attained in response to Ang II, endothelin-1 and phenylephrine were greater. Tempol significantly and selectively reduced the Emax of Ang II in both aorta and MVB preparations with intact endothelium. The reduction in Emax attained in response to Ang II was more pronounced in SHRs (P < 0.01) than in WKY rats (P < 0.05) or Sprague-Dawley rats (P < 0.05). The inhibitory effect of tempol was absent when a nitric oxide synthase inhibitor was included or endothelium was denuded. A significant increase in lucigenin chemiluminescence evoked by Ang II in both intact and endothelium-denuded aortic rings of SHRs was abolished when tempol was included in the buffer. CONCLUSIONS: These data suggest that increased superoxide anions mediate vasoconstrictor responses to Ang II, but not to other agonists, in an endothelium-dependent manner, by quenching vasodilatory mediator, nitric oxide. This may account for the exaggerated vasoconstrictor responses to Ang II in SHRs.
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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 | 0.000 |
| 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".