Beta-adrenergic receptors in skeletal muscles of ruminants: Effects of temperature and feed intake
Bibliographic record
Abstract
Adrenergic receptors mediate effects of catecholamines on physiological processes including protein and energy metabolism. We determined the effects of temperature and feed intake on beta-1 and beta-2 adrenergic receptors (β1 AR and β2 AR) in skeletal muscle of lambs to assess the potential to modify physiological responses through adrenergic receptors. Twenty-four wether lambs received either restricted (R) or ad libitum (A) levels of feed intake, and were exposed to either cold (C; 0 ± 2 °C) or warm (W; 23 ± 2 °C) temperatures, resulting in four experimental treatment groups (WA, WR, CA and CR). At the end of 4 mo the lambs were slaughtered and biceps femoris, semitendinosus and gastrocnemius muscles were harvested for isolation of plasma membrane. Binding of [ 3 H]dihydroalprenolol to crude plasma membrane was used to determine the β AR densities and binding affinities (Kd). The densities of β1 AR were 28.02 ± 4.17, 40.68 ± 2.26, 28.99 ± 4.68 and 55.56 ± 6.05 fmol mg −1 protein for biceps femoris, 29.35 ± 1.49, 35.34 ± 2.59, 28.36 ± 2.94 and 37.89 ± 3.30 fmol mg −1 protein for gastrocnemius, and 22.66 ± 2.66, 31.21 ± 4.65, 21.84 ± 1.81 and 38.62 ± 3.67 fmol mg −1 protein for semitendinosus, for WA, WR, CA and CR, respectively. The Kd values for all groups ranged from 1.7 to 8.5 nM for β1 AR. Feed restriction increased (P < 0.01) the density of β1 AR in both environments but there was no significant effect of temperature. β1 AR densities and binding affinities were significantly higher in biceps femoris than in gastrocnemius and semitendinosus muscles when feed intake was restricted. The densities of β2 AR ranged from 9.0 to 16.0 fmol mg −1 protein. There was no effect of treatments on the density or receptor binding affinity of β2 AR in muscles. It is concluded that feed restriction causes increased density of β1 AR in sheep and that feed restriction could potentially increase the metabolic responsiveness of skeletal muscle to elevated levels of catecholamines. Key words: Catecholamine receptors, skeletal muscle, temperature, feed
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".