Skeletal Muscle Na+-K+-ATPase Responses to Prolonged Exercise preceded by Conditioning Exercise and a Normal Diet
Bibliographic record
Abstract
PURPOSE: In this study, the effects of prolonged exercise on muscle Na+-K+-ATPase function in females was investigated following initial conditioning exercise and a normal diet. METHODS: Eight untrained females (VO2peak = 38.08 ± 1.38 mL/kg/min) cycled at ∼55% of their peak aerobic power (VO2peak) on two randomized occasions; namely following a normal 4-day diet (NCHO) and following an initial session of conditioning exercise plus a 4-day normal diet (EX+NCHO). Muscle samples from the vastus lateralis were collected at rest, 30 and 60 min of exercise, and at fatigue. Maximal Na+-K+-ATPase activity (Vmax) was assessed using the 3-O-methylfluorescein phosphatase assay while the maximal number of alpha subunits (Bmax) was measured using the [3H] ouabain binding technique. RESULTS: Compared to rest, reduction (p<.01) in Vmax (nmole/mg protein/h) at fatigue was not different between NCHO (Rest 66 ± 9; Fatigue 37 ± 5) and EX+NCHO (Rest 67 ± 7; Fatigue 51 ±7). Regardless of condition, Bmax (pmol/g) increased (p<.05) from rest to fatigue (NCHO: 255 ± 12 vs. 294 ± 10; EX+NCHO: 256 ± 14 vs. 285 ± 13). There was no effect of condition on Bmax. Exercise to fatigue in NCHO reduced (p<.001) muscle glycogen (Rest 421.6 ± 33.9; Fatigue 151.7 ± 32 mmol glucosyl units/kg dry wt). No difference was observed in muscle glycogen concentration at any time point between NCHO and EX+NCHO. CONCLUSIONS: These results suggest that exercise results in an inhibition of the maximal hydrolytic Na+-K+-ATPase activity (Vmax), most likely through structural alterations in the enzyme. Also, there is an increase in the alpha subunit abundance which suggests a translocation of alpha subunits to the sarcolemma. None of these properties are altered by a preceding bout of exercise while on a normal CHO diet.
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) | 0.002 | 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".