Maximum cardiac performance and adrenergic sensitivity of the sea bass<i>Dicentrarchus labrax</i>at high temperatures
Bibliographic record
Abstract
We examined maximum cardiac performance of sea bass Dicentrarchus labrax acclimated to 18 degrees C and 22 degrees C, temperatures near the optimum for growth of this species. Our aim was to study whether cardiac performance, especially the effect of adrenergic stimulation, differed when compared to salmonids. Sea bass and salmonids are both athletic swimmers but their cardiac anatomy differs markedly. The sea bass ventricle does not receive any oxygenated blood via a coronary circulation while salmonids have a well-developed arterial supply of oxygen to the compact layer of the ventricle. Using in situ perfused heart preparations, maximum cardiac performance of 18 degrees C-acclimated sea bass (i.e. cardiac output = 90.8+/- 6.6 ml min(-1) kg(-1) and power output = 11.41+/-0.83 mW g(-1)) was found to be comparable to that previously reported for rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta at similar temperatures and with tonic adrenergic (5 nmol l(-1) adrenaline) stimulation. For 22 degrees C-acclimated sea bass, heart rate was significantly higher, but maximum stroke volume was reduced by 22% (1.05+/-0.05 ml kg(-1)) compared with 18 degrees C (1.38+/- 0.11 ml kg(-1)). As a result, maximum cardiac output (99.4+/-3.9 ml min(-1) kg(-1)) was not significantly different at 22 degrees C. Instead, maximum power output was 27% higher at 22 degrees C (14.95+/-0.96 mW g(-1)) compared with 18 degrees C, primarily because of the smaller relative ventricular mass in 22 degrees C-acclimated sea bass. Compared with tonic adrenergic stimulation with 5 nmol l(-1) adrenaline, maximum adrenergic stimulation of the sea bass heart produced only modest stimulatory effects at both temperatures (12-13% and 14-15% increases in maximum cardiac output and power output, respectively, with no chronotropic effect). Adrenergic stimulation also increased the cardiac sensitivity to filling pressure, with the maximum left-shift in the Starling curve being produced by 50-100 nmol l(-1) adrenaline at 18 degrees C and 10-50 nmol l(-1) adrenaline at 22 degrees C. We show that the sea bass, which lacks a coronary arterial oxygen supply to the ventricle, has a powerful heart. Its maximum performance is comparable to a salmonid heart, as is the modest stimulatory effect of adrenaline at high temperature.
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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) | 0.001 | 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".