Endothelin-1 Induces an Endothelin-A-Receptor-Dependent and L-NAME-Sensitive Vasoconstriction in the Isolated Perfused Guinea-Pig Kidney
Bibliographic record
Abstract
We have previously reported a significant contribution of ET(A)- and ET(B)-receptors in the eicosanoid-releasing properties of endothelin-1 (ET-1) in the guinea-pig perfused lung. More recently, it was found that intravenously administered ET-1 in the guinea-pig triggers the release of hypotensive and bronchoconstrictive eicosanoids which is strongly modulated by endogenous nitric oxide. In this study we investigate the contribution of both ET receptors as well as of the eicosanoids and nitric oxide to the vasoconstrictor properties of ET-1 in the guinea-pig kidney. The kidney was isolated from stunned and spinal cord-sectioned guinea-pig (300-350 g) and rapidly suspended and perfused (3 ml/min) with oxygenated Krebs solution at 37 degrees C. ET-1 (1-1000 pmol) induced dose-dependent increases in perfusion pressure in the perfused guinea-pig kidney. Furthermore, the pressor effect of a dose of ET-1 (40 pmol) was markedly reduced after a 15-min infusion of the ET(A) antagonist, BQ-123 (1 microM). The ET-1-induced vasoconstriction was restored 50 min after the cessation of BQ-123 infusion. In contrast, the selective ET(B)-receptor agonist, IRL-1620 (1-1000 pmol) was found to be inactive. Indomethacin (5 microM) and the ET(B)-receptor antagonist, BQ-788 (10 nM) did not affect the constrictor effect of ET-1. The infusion of ET-1 (0.5 and 1 microM, 5 min) in the guinea-pig kidney did not induce the release of prostacyclin or thromboxane. Finally, a 60 min infusion with the nitric oxide synthase inhibitor, L-NAME (200 microM) markedly potentiated the constrictor effects of ET-1. Our results suggest that unlike the pulmonary vasculature, the guinea-pig kidney responds to ET-1 by a direct constriction, which is modulated by nitric oxide but not eicosanoids (supported by the MRCC).
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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) | 0.001 | 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) | 0.002 | 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".