Novel Actions of Relaxin Producing Vasodilation in Skeletal Muscle.
Bibliographic record
Abstract
Relaxin consistently causes vasodilation in small diameter arterioles in a number of vascular beds including: the mesocaecum, uterus, kidney and the heart. The purpose of the present study was to examine the affects of relaxin on the dilation of small arterioles (<100μm) in skeletal muscle. The effects of relaxin applied onto branches of the microcirculation in an exposed hamster cremaster muscle preparation were studied to explore whether or not (a) relaxin caused vasodilation and (b) to elucidate second messenger pathways of the response. Pathways investigated included: nitric oxide (NO); ATP-sensitive potassium channels (KATP); calcium-associated potassium channels (KCa); protein kinase A (PKA); and phosphoinositide-3 kinase (PI3K). Relaxin consistently produced vasodilation in transverse arterioles employing concentrations ranging from 10-12M to 10-5M. Vasodilation was observed ≈20 s after application and reached peak dilation ≈120 s after onset of treatment. Over the next three minutes, the degree of dilation waned until blood vessel diameter returned to baseline values approximately five minutes after onset of treatment. In the second set of experiments, specific blockers for potential second messengers were tested on the vasodilatory response. These included: 10-5M N (G)-nitro-L-arginine methyl ester (a blocker of nitric oxide synthase); 10-5M glibenclamide (KATP inhibitor); 10-3M tetraethylammonium (KCa inhibitor); 2x10-5M 5-24 Amide (an inhibitor of PKA); and 10-8M wortmannin (an inhibitor of PI3K). In each case, the vasodilatory effect of a relaxin (10-10M) was compared with the response to the same dose of relaxin after incubation with the blocker for 30 minutes (60 minutes in the case of tetraethylammonium [TEA]). All blockers significantly (p < 0.05) reduced vasodilation in response to relaxin. The blocker was washed out of the preparation for a further 30 minutes (60 minutes for TEA) and the effect of relaxin (10-10M) tested again on the preparation. In all cases, the response to relaxin was restored, suggesting that the effects of the blockers were specific and reversible. These data imply that relaxin induces vasodilation in transverse arterioles in skeletal muscle in the hamster through NO, KATP, and KCa that may be mediated by PKA and PI3K. Given that skeletal muscle is such a large vascular bed (≈40% in humans), the findings that relaxin induces vasodilation in this tissue suggest that there may be an important role for the hormone in cardiovascular function. Funding provided by NSERC and the University of Guelph. (poster)
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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) | 0.000 | 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".