Biphasic Actions of Prostaglandin E<sub>2</sub>on the Renal Afferent Arteriole
Bibliographic record
Abstract
Prostaglandin (PG) E(2) is an important modulator of the actions of angiotensin (Ang) II. In the present study, we investigated the renal microvascular actions of PGE(2) and the EP receptor subtypes involved. Ibuprofen potentiated Ang II-induced vasoconstriction in in vitro perfused normal rat kidneys and augmented afferent arteriolar, but not efferent arteriolar, responses in the hydronephrotic rat kidney model. This preglomerular effect of endogenous prostanoids was mimicked by exogenous PGE(2), which reversed Ang II-induced afferent arteriolar vasoconstriction at concentrations of 0.1 to 10 nmol/L without affecting the efferent arteriole. The PGE(2)-induced vasodilation was potentiated by the phosphodiesterase inhibitor Ro 20-1724 and was mimicked by 11-deoxy-PGE(1) (0.01 to 1 nmol/L). Butaprost, which acts preferentially at EP(2) receptors, was relatively ineffective. Whereas 0.1 to 10 nmol/L PGE(2) elicited vasodilation, higher concentrations (1 to 10 micromol/L) restored Ang II-induced afferent arteriolar vasoconstriction. This response was blocked by pertussis toxin (200 microg/mL) and was mimicked by the EP(1)/EP(3) agonist sulprostone (1 to 300 nmol/L). Reverse transcription-polymerase chain reaction of individually isolated afferent arterioles revealed the presence of message for EP(4) and all 3 EP(3) splice variants (alpha, beta, and gamma) but not EP(1) or EP(2). Our findings thus indicate that PGE(2) elicits both vasodilatory and vasoconstrictor actions on the afferent arteriole. The vasodilation is mediated by EP(4) receptors coupled to cAMP, presumably via G(alphas). The vasoconstriction is mediated by an EP(3) receptor coupled to G(alphai) and appears to reflect a functional antagonism of the EP(4)-induced vasodilation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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".