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.
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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 | 0.000 | 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) | 0.000 | 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".