Vastus lateralis NA<sup>+</sup>‐K<sup>+</sup>‐ATpase activity, protein, and isoform distribution in chronic obstructive pulmonary disease
Bibliographic record
Abstract
In this study we investigate the hypothesis that protein abundance, isoform distribution, and maximal catalytic activity of sodium-potassium-adenosine triphosphatase (Na(+)-K(+)-ATPase) would be altered in muscle of patients with moderate to severe chronic obstructive pulmonary disease (COPD). Tissue samples were obtained from the vastus lateralis of 10 patients with COPD (mean +/- SE: age = 67 +/- 2.9 years; FEV1 = 39 +/- 5.5%) and 10 healthy, matched controls (CON: age = 68 +/- 2 years; FEV1 = 114 +/- 4.2%). The samples were assessed for maximal catalytic activity (Vmax) of the enzyme using the K(+)-stimulated 3-O-methylfluorescein-phosphatase (3-O-MFPase) assay, enzyme abundance using the [3H]-ouabain assay, and isoform content of both alpha (alpha1, alpha2, alpha3) and beta (beta1, beta2, beta3) using Western blot techniques. A 19.4% lower (P < 0.05) Vmax was observed in COPD compared with CON (90.7 +/- 6.7 vs. 73.1 +/- 4.7 nmol x mg protein(-1) h(-1)). No differences between groups were observed for pump concentration (259 +/- 15 vs. 243 +/- 17 pmol x g wet weight). For the isoforms, alpha1 was decreased by 28% (P < 0.05), and alpha2 was increased by 12% (P < 0.05) in COPD compared with CON. No differences between groups were observed for alpha3 or for the beta isoforms. We conclude that moderate COPD compromises Vmax, which occurs in the absence of changes in pump abundance. The reduction in Vmax could be due to a shift in isoform expression (alpha1, alpha2), alterations in intrinsic regulation, or to structural changes in the enzyme. The changes observed in the catalytic activity of the pump could have major effects on membrane excitability and fatigability, which are typically compromised in COPD.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".