Activation of proteinase activated receptor‐2 (PAR‐2) inhibits spontaneous activity in rat colon
Bibliographic record
Abstract
Proteolytic cleavage of proteinase activated receptor‐2 (PAR‐2) reveals a tethered ligand which binds to and activates the receptor. Rat colonic smooth muscle shows spontaneous contractile activity which is generated by pacemaker cells. This study investigated the effects of PAR‐2 activation on spontaneous contractile activity in the isolated rat colon. Strips of rat colon longitudinal muscle were suspended in organ baths and increasing concentrations of trypsin, or the mimetic peptide FLIGRL, were applied. In some experiments carbachol was used to increase smooth muscle tone. Trypsin and FLIGRL each induced concentration‐dependent inhibition of spontaneous contractile activity of rat colon. Trypsin‐evoked relaxations (66.6±3.3; n=8) were abolished by apamin, an inhibitor of small conductance Ca 2+ ‐activated potassium channels (SK Ca ). Similar results were obtained with FLIGRL (n=5). Cyclopiazonic acid, an inhibitor of sarcoplasmic reticulum Ca 2+ ‐ATPase, also abolished the effects of trypsin (n=7). Neither trypsin (n=4) nor FLIGRL (n=4) reduced carbachol‐induced tone. In conclusion, activation of PAR‐2 inhibits spontaneous contractile activity in the rat colon via release of Ca 2+ from intracellular stores and activation of SK Ca channels. PAR‐2 activation is limited to pacemaker cells since no effect was observed on carbachol stimulated smooth muscle. Supported by NSERC
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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) | 0.000 | 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 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 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".