A294 NORADRENALINE INHIBITS PROPULSIVE MOTOR PATTERNS BUT NOT SEGMENTING HAUSTRAL PROGRESSION IN THE RABBIT 3-TAENIATED COLON
Bibliographic record
Abstract
Sympathetic inhibition may be an underestimated cause of reduced human colonic motor activity. The sympathetic nervous system has been implicated in colonic dysmotilities involving stress or anxiety. Our aim was to better understand the role of sympathetic inhibition on colonic motor patterns and to formulate a hypothesis on the underlying mechanisms Sympathetic activity was studied ex vivo using noradrenaline on four major motor patterns occurring in the rabbit 3-taeniated colon (n=11): long distance contractions (LDCs), fast propagating contractions (FPCs), haustral boundary contractions (HBCs) and ripples. Spatiotemporal maps were created to show diameter changes of the whole proximal colon over time. The rabbit colon displayed four motor patterns that appeared under baseline conditions in various combinations, LDCs at 0.9 ± 0.4 cycles/min (cpm) and velocity of 3.0 ± 0.6 cm/s, FPCs at 13.7 ± 5.1 cpm and 3.4 ± 0.9 cm/s, HBCs at a frequency of 0.5 ± 0.2 cpm and velocity of 8.2 ± 2.0 mm/min and ripples at 8.6 ± 1.6 cpm. Noradrenaline (10–6 M) abolished LDCs, which recovered by the alpha-2 adrenergic blocker yohimbine (10–6 M) to 0.6 ± 0.1 cpm and velocity of 2.9 ± 0.4 cm/s, not by the beta-adrenergic blocker propranolol (10–6 M). The FPCs were transiently abolished but recovered in the presence of noradrenaline at 30 min with FPCs at 1.6 ± 0.1 cpm and 4.6 ± 1.9 cm/s, and recovered further with yohimbine at a frequency of 10.7 ± 4.5 cpm and 3.7 ± 1.3 cm/s. The features of HBCs in the presence of noradrenaline, a frequency of 0.5 ± 0.1 cpm at 7.9 ± 1.0 mm/min, were not different from control values. In the presence of noradrenaline, the myogenic ripples did not change at a frequency of 10.2 ± 1.8 cpm. Noradrenaline affected preferentially the propulsive motor patterns, the LDCs and FPCs, mediated by the alpha-2 adrenergic receptor. No role for the beta-adrenergic receptor was found. We propose that the human manometry equivalent of the LDC is the High Amplitude Pressure Wave (1) and that the FPCs create simultaneous pressure waves in the rabbit (2) and human colon (1). Noradrenaline did not have a marked effect on ripples or the propagating HBCs. The lack of effect on the rhythmic myogenic component of these motor patterns suggests an absence of noradrenergic communication with interstitial cells of Cajal (ICC). The HBCs also have a neurogenic component hence alpha-2 receptors appear present in some neuronal circuitries (to generate LDCs) but not in others (to generate HBCs). This knowledge may help to discover a role for sympathetic inhibition, based on motor patterns affected, as measured by high-resolution manometry in the human colon (1). 1. Chen, J-H. et al. Nature’s Scientific Reports 2017;7:41436; doi:10.1038/srep41436. 2. Quan, X et al., Nature’s Scientific Reports 2017;7:42293:doi:10.1038/srep42293. Rabbit colon spatiotemporal maps of diameter changes over time in vitro. Baseline shows LDCs, FPCs and propagating haustral boundary contractions. LDCs and FPCs are inhibited by noradrenaline but LDCs recover in the presence of the alpha-2 blocker yohimbine. CIHR
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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 | 0.001 |
| 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 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".