Calcium extrusion by plasma membrane calcium pump is impaired in absence of intact caveolae
Bibliographic record
Abstract
Plasma membrane calcium ATPase (PMCA) is an important calcium extrusion mechanism in smooth muscle cells with PMCA4 as the predominant isoform. PMCA is localized in lipid rafts and caveolae. In this study we examined the effects of blocking PMCA4 function in small intestinal tissue from wild type (Cav1+/+) and caveolin‐1 knockout (Cav1−/−) mice and in bovine airway smooth muscle tissue before and after caveolae disruption. Small intestinal tissues from Cav1+/+ mice treated with the PMCA4 inhibitor caloxin 1c2 (5 μM) showed a higher contractile tone to carbachol (10 μM) when compared to tissues treated with 5 μM of a control scrambled peptide. This effect of caloxin 1c2 was not seen in tissues from Cav1−/− mice. Immunohistochemistry and Western blotting showed that PMCA was co‐localized with caveolin‐1 in Cav1+/+ tissues. In bovine tracheal smooth muscle tissue, caveolae disruption by cholesterol depletion led to the diminution of caveolin‐1 and PMCA4b immunoreactivities, previously co‐localized in the smooth muscle plasma membrane, and to the loss of the increase in carbachol‐induced contraction by caloxin 1c2. Our results suggest that the calcium removal function of PMCA4 in smooth muscle cells is dependent on its presence in intact caveolae. We suggest that this is due to the close spatial arrangement that allows calcium extrusion from a privileged cytosolic space between caveolae and sarcoplasmic reticulum.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".